It appears that amdgpu makes the mistake of completely ignoring the return values from the DP MST helpers, and instead just returns a simple true/false. In this case, it seems to have come back to bite us because as a result of simply returning false from compute_mst_dsc_configs_for_state(), amdgpu had no way of telling when a deadlock happened from these helpers. This could definitely result in some kernel splats.
Signed-off-by: Lyude Paul lyude@redhat.com Fixes: 8c20a1ed9b4f ("drm/amd/display: MST DSC compute fair share") Cc: Harry Wentland harry.wentland@amd.com Cc: stable@vger.kernel.org # v5.6+ --- .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 18 +-- .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 107 ++++++++++-------- .../display/amdgpu_dm/amdgpu_dm_mst_types.h | 12 +- 3 files changed, 73 insertions(+), 64 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 0db2a88cd4d7b..6f76b2c84cdb5 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -6462,7 +6462,7 @@ static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state, struct drm_connector_state *new_con_state; struct amdgpu_dm_connector *aconnector; struct dm_connector_state *dm_conn_state; - int i, j; + int i, j, ret; int vcpi, pbn_div, pbn, slot_num = 0;
for_each_new_connector_in_state(state, connector, new_con_state, i) { @@ -6509,8 +6509,11 @@ static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state, dm_conn_state->pbn = pbn; dm_conn_state->vcpi_slots = slot_num;
- drm_dp_mst_atomic_enable_dsc(state, aconnector->port, dm_conn_state->pbn, - false); + ret = drm_dp_mst_atomic_enable_dsc(state, aconnector->port, + dm_conn_state->pbn, false); + if (ret != 0) + return ret; + continue; }
@@ -9523,10 +9526,9 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
#if defined(CONFIG_DRM_AMD_DC_DCN) if (dc_resource_is_dsc_encoding_supported(dc)) { - if (!pre_validate_dsc(state, &dm_state, vars)) { - ret = -EINVAL; + ret = pre_validate_dsc(state, &dm_state, vars); + if (ret != 0) goto fail; - } } #endif
@@ -9621,9 +9623,9 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev, }
#if defined(CONFIG_DRM_AMD_DC_DCN) - if (!compute_mst_dsc_configs_for_state(state, dm_state->context, vars)) { + ret = compute_mst_dsc_configs_for_state(state, dm_state->context, vars); + if (ret) { DRM_DEBUG_DRIVER("compute_mst_dsc_configs_for_state() failed\n"); - ret = -EINVAL; goto fail; }
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c index 6ff96b4bdda5c..30bc2e5058b70 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c @@ -864,25 +864,25 @@ static bool try_disable_dsc(struct drm_atomic_state *state, return true; }
-static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, - struct dc_state *dc_state, - struct dc_link *dc_link, - struct dsc_mst_fairness_vars *vars, - struct drm_dp_mst_topology_mgr *mgr, - int *link_vars_start_index) +static int compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, + struct dc_state *dc_state, + struct dc_link *dc_link, + struct dsc_mst_fairness_vars *vars, + struct drm_dp_mst_topology_mgr *mgr, + int *link_vars_start_index) { struct dc_stream_state *stream; struct dsc_mst_fairness_params params[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; struct drm_dp_mst_topology_state *mst_state = drm_atomic_get_mst_topology_state(state, mgr); int count = 0; - int i, k; + int i, k, ret; bool debugfs_overwrite = false;
memset(params, 0, sizeof(params));
if (IS_ERR(mst_state)) - return false; + return PTR_ERR(mst_state);
mst_state->pbn_div = dm_mst_get_pbn_divider(dc_link); #if defined(CONFIG_DRM_AMD_DC_DCN) @@ -933,7 +933,7 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
if (count == 0) { ASSERT(0); - return true; + return 0; }
/* k is start index of vars for current phy link used by mst hub */ @@ -949,11 +949,14 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, vars[i + k].bpp_x16 = 0; if (drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, vars[i + k].pbn) < 0) - return false; + return -EINVAL; } - if (!drm_dp_mst_atomic_check(state) && !debugfs_overwrite) { + ret = drm_dp_mst_atomic_check(state); + if (ret == 0 && !debugfs_overwrite) { set_dsc_configs_from_fairness_vars(params, vars, count, k); - return true; + return 0; + } else if (ret == -EDEADLK) { + return ret; }
/* Try max compression */ @@ -964,29 +967,30 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, vars[i + k].bpp_x16 = params[i].bw_range.min_target_bpp_x16; if (drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, vars[i + k].pbn) < 0) - return false; + return -EINVAL; } else { vars[i + k].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps); vars[i + k].dsc_enabled = false; vars[i + k].bpp_x16 = 0; if (drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, vars[i + k].pbn) < 0) - return false; + return -EINVAL; } } - if (drm_dp_mst_atomic_check(state)) - return false; + ret = drm_dp_mst_atomic_check(state); + if (ret != 0) + return ret;
/* Optimize degree of compression */ if (!increase_dsc_bpp(state, mst_state, dc_link, params, vars, count, k)) - return false; + return -ENOSPC;
if (!try_disable_dsc(state, dc_link, params, vars, count, k)) - return false; + return -ENOSPC;
set_dsc_configs_from_fairness_vars(params, vars, count, k);
- return true; + return 0; }
static bool is_dsc_need_re_compute( @@ -1087,15 +1091,16 @@ static bool is_dsc_need_re_compute( return is_dsc_need_re_compute; }
-bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, - struct dc_state *dc_state, - struct dsc_mst_fairness_vars *vars) +int compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, + struct dc_state *dc_state, + struct dsc_mst_fairness_vars *vars) { int i, j; struct dc_stream_state *stream; bool computed_streams[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; int link_vars_start_index = 0; + int ret = 0;
for (i = 0; i < dc_state->stream_count; i++) computed_streams[i] = false; @@ -1118,17 +1123,19 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, continue;
if (dcn20_remove_stream_from_ctx(stream->ctx->dc, dc_state, stream) != DC_OK) - return false; + return -EINVAL;
if (!is_dsc_need_re_compute(state, dc_state, stream->link)) continue;
mutex_lock(&aconnector->mst_mgr.lock); - if (!compute_mst_dsc_configs_for_link(state, dc_state, stream->link, vars, - &aconnector->mst_mgr, - &link_vars_start_index)) { + + ret = compute_mst_dsc_configs_for_link(state, dc_state, stream->link, vars, + &aconnector->mst_mgr, + &link_vars_start_index); + if (ret != 0) { mutex_unlock(&aconnector->mst_mgr.lock); - return false; + return ret; } mutex_unlock(&aconnector->mst_mgr.lock);
@@ -1143,22 +1150,22 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
if (stream->timing.flags.DSC == 1) if (dc_stream_add_dsc_to_resource(stream->ctx->dc, dc_state, stream) != DC_OK) - return false; + return -EINVAL; }
- return true; + return ret; }
-static bool - pre_compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, - struct dc_state *dc_state, - struct dsc_mst_fairness_vars *vars) +static int pre_compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, + struct dc_state *dc_state, + struct dsc_mst_fairness_vars *vars) { int i, j; struct dc_stream_state *stream; bool computed_streams[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; int link_vars_start_index = 0; + int ret;
for (i = 0; i < dc_state->stream_count; i++) computed_streams[i] = false; @@ -1184,13 +1191,12 @@ static bool continue;
mutex_lock(&aconnector->mst_mgr.lock); - if (!compute_mst_dsc_configs_for_link(state, dc_state, stream->link, vars, - &aconnector->mst_mgr, - &link_vars_start_index)) { - mutex_unlock(&aconnector->mst_mgr.lock); - return false; - } + ret = compute_mst_dsc_configs_for_link(state, dc_state, stream->link, vars, + &aconnector->mst_mgr, + &link_vars_start_index); mutex_unlock(&aconnector->mst_mgr.lock); + if (ret != 0) + return ret;
for (j = 0; j < dc_state->stream_count; j++) { if (dc_state->streams[j]->link == stream->link) @@ -1198,7 +1204,7 @@ static bool } }
- return true; + return ret; }
static int find_crtc_index_in_state_by_stream(struct drm_atomic_state *state, @@ -1253,9 +1259,9 @@ static bool is_dsc_precompute_needed(struct drm_atomic_state *state) return ret; }
-bool pre_validate_dsc(struct drm_atomic_state *state, - struct dm_atomic_state **dm_state_ptr, - struct dsc_mst_fairness_vars *vars) +int pre_validate_dsc(struct drm_atomic_state *state, + struct dm_atomic_state **dm_state_ptr, + struct dsc_mst_fairness_vars *vars) { int i; struct dm_atomic_state *dm_state; @@ -1264,11 +1270,12 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
if (!is_dsc_precompute_needed(state)) { DRM_INFO_ONCE("DSC precompute is not needed.\n"); - return true; + return 0; } - if (dm_atomic_get_state(state, dm_state_ptr)) { + ret = dm_atomic_get_state(state, dm_state_ptr); + if (ret != 0) { DRM_INFO_ONCE("dm_atomic_get_state() failed\n"); - return false; + return ret; } dm_state = *dm_state_ptr;
@@ -1280,7 +1287,7 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
local_dc_state = kmemdup(dm_state->context, sizeof(struct dc_state), GFP_KERNEL); if (!local_dc_state) - return false; + return -ENOMEM;
for (i = 0; i < local_dc_state->stream_count; i++) { struct dc_stream_state *stream = dm_state->context->streams[i]; @@ -1316,9 +1323,9 @@ bool pre_validate_dsc(struct drm_atomic_state *state, if (ret != 0) goto clean_exit;
- if (!pre_compute_mst_dsc_configs_for_state(state, local_dc_state, vars)) { + ret = pre_compute_mst_dsc_configs_for_state(state, local_dc_state, vars); + if (ret != 0) { DRM_INFO_ONCE("pre_compute_mst_dsc_configs_for_state() failed\n"); - ret = -EINVAL; goto clean_exit; }
@@ -1349,7 +1356,7 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
kfree(local_dc_state);
- return (ret == 0); + return ret; }
static unsigned int kbps_from_pbn(unsigned int pbn) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h index b92a7c5671aa2..97fd70df531bf 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h @@ -53,15 +53,15 @@ struct dsc_mst_fairness_vars { struct amdgpu_dm_connector *aconnector; };
-bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, - struct dc_state *dc_state, - struct dsc_mst_fairness_vars *vars); +int compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, + struct dc_state *dc_state, + struct dsc_mst_fairness_vars *vars);
bool needs_dsc_aux_workaround(struct dc_link *link);
-bool pre_validate_dsc(struct drm_atomic_state *state, - struct dm_atomic_state **dm_state_ptr, - struct dsc_mst_fairness_vars *vars); +int pre_validate_dsc(struct drm_atomic_state *state, + struct dm_atomic_state **dm_state_ptr, + struct dsc_mst_fairness_vars *vars);
enum dc_status dm_dp_mst_is_port_support_mode( struct amdgpu_dm_connector *aconnector,
[Public]
Thanks, Lyude! Comments inline.
-----Original Message----- From: Lyude Paul lyude@redhat.com Sent: Saturday, November 5, 2022 7:59 AM To: amd-gfx@lists.freedesktop.org Cc: Wentland, Harry Harry.Wentland@amd.com; stable@vger.kernel.org; Li, Sun peng (Leo) Sunpeng.Li@amd.com; Siqueira, Rodrigo Rodrigo.Siqueira@amd.com; Deucher, Alexander Alexander.Deucher@amd.com; Koenig, Christian Christian.Koenig@amd.com; Pan, Xinhui Xinhui.Pan@amd.com; David Airlie airlied@gmail.com; Daniel Vetter daniel@ffwll.ch; Kazlauskas, Nicholas Nicholas.Kazlauskas@amd.com; Pillai, Aurabindo Aurabindo.Pillai@amd.com; Li, Roman Roman.Li@amd.com; Zuo, Jerry Jerry.Zuo@amd.com; Wu, Hersen hersenxs.wu@amd.com; Lin, Wayne Wayne.Lin@amd.com; Thomas Zimmermann tzimmermann@suse.de; Mahfooz, Hamza Hamza.Mahfooz@amd.com; Hung, Alex Alex.Hung@amd.com; Francis, David David.Francis@amd.com; Mikita Lipski mikita.lipski@amd.com; Liu, Wenjing Wenjing.Liu@amd.com; open list:DRM DRIVERS dri-devel@lists.freedesktop.org; open list <linux- kernel@vger.kernel.org> Subject: [PATCH 1/2] drm/amdgpu/mst: Stop ignoring error codes and deadlocking
It appears that amdgpu makes the mistake of completely ignoring the return values from the DP MST helpers, and instead just returns a simple true/false. In this case, it seems to have come back to bite us because as a result of simply returning false from compute_mst_dsc_configs_for_state(), amdgpu had no way of telling when a deadlock happened from these helpers. This could definitely result in some kernel splats.
Signed-off-by: Lyude Paul lyude@redhat.com Fixes: 8c20a1ed9b4f ("drm/amd/display: MST DSC compute fair share") Cc: Harry Wentland harry.wentland@amd.com Cc: stable@vger.kernel.org # v5.6+
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 18 +-- .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 107 ++++++++++------ -- .../display/amdgpu_dm/amdgpu_dm_mst_types.h | 12 +- 3 files changed, 73 insertions(+), 64 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 0db2a88cd4d7b..6f76b2c84cdb5 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -6462,7 +6462,7 @@ static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state, struct drm_connector_state *new_con_state; struct amdgpu_dm_connector *aconnector; struct dm_connector_state *dm_conn_state;
- int i, j;
int i, j, ret; int vcpi, pbn_div, pbn, slot_num = 0;
for_each_new_connector_in_state(state, connector,
new_con_state, i) { @@ -6509,8 +6509,11 @@ static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state, dm_conn_state->pbn = pbn; dm_conn_state->vcpi_slots = slot_num;
drm_dp_mst_atomic_enable_dsc(state, aconnector-port, dm_conn_state->pbn,
false);
ret = drm_dp_mst_atomic_enable_dsc(state,aconnector->port,
dm_conn_state-pbn, false);
if (ret != 0)return ret;continue;@@ -9523,10 +9526,9 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
#if defined(CONFIG_DRM_AMD_DC_DCN) if (dc_resource_is_dsc_encoding_supported(dc)) {
if (!pre_validate_dsc(state, &dm_state, vars)) {ret = -EINVAL;
ret = pre_validate_dsc(state, &dm_state, vars);if (ret != 0) goto fail;
}#endif
@@ -9621,9 +9623,9 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev, }
#if defined(CONFIG_DRM_AMD_DC_DCN)
if (!compute_mst_dsc_configs_for_state(state, dm_state-context, vars)) {
ret = compute_mst_dsc_configs_for_state(state, dm_state-context, vars);
if (ret) {DRM_DEBUG_DRIVER("compute_mst_dsc_configs_for_state()
failed\n");
ret = -EINVAL; goto fail;diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c index 6ff96b4bdda5c..30bc2e5058b70 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c @@ -864,25 +864,25 @@ static bool try_disable_dsc(struct drm_atomic_state *state, return true; }
-static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dc_link *dc_link,struct dsc_mst_fairness_vars *vars,struct drm_dp_mst_topology_mgr*mgr,
int *link_vars_start_index)+static int compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dc_link *dc_link,struct dsc_mst_fairness_vars *vars,struct drm_dp_mst_topology_mgr*mgr,
int *link_vars_start_index){ struct dc_stream_state *stream; struct dsc_mst_fairness_params params[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; struct drm_dp_mst_topology_state *mst_state = drm_atomic_get_mst_topology_state(state, mgr); int count = 0;
- int i, k;
int i, k, ret; bool debugfs_overwrite = false;
memset(params, 0, sizeof(params));
if (IS_ERR(mst_state))
return false;
return PTR_ERR(mst_state);mst_state->pbn_div = dm_mst_get_pbn_divider(dc_link); #if
defined(CONFIG_DRM_AMD_DC_DCN) @@ -933,7 +933,7 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
if (count == 0) { ASSERT(0);
return true;
return 0;}
/* k is start index of vars for current phy link used by mst hub */ @@
-949,11 +949,14 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, vars[i + k].bpp_x16 = 0; if (drm_dp_atomic_find_time_slots(state, params[i].port-
mgr, params[i].port,
vars[i + k].pbn) < 0)
return false;
return -EINVAL;
Should we also return the error code get from drm_dp_atomic_find_time_slots() rather than assigning a new one here?
}
- if (!drm_dp_mst_atomic_check(state) && !debugfs_overwrite) {
- ret = drm_dp_mst_atomic_check(state);
- if (ret == 0 && !debugfs_overwrite) { set_dsc_configs_from_fairness_vars(params, vars, count, k);
return true;
return 0;- } else if (ret == -EDEADLK) {
return ret;
I think we should return here whenever there is an error. Not just for EDEADLK case.
}
/* Try max compression */ @@ -964,29 +967,30 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, vars[i + k].bpp_x16 = params[i].bw_range.min_target_bpp_x16; if (drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, vars[i
- k].pbn) < 0)
return false;
return -EINVAL;
Same as above.
} else { vars[i + k].pbn =kbps_to_peak_pbn(params[i].bw_range.stream_kbps); vars[i + k].dsc_enabled = false; vars[i + k].bpp_x16 = 0; if (drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, vars[i
- k].pbn) < 0)
return false;
return -EINVAL;
Same as above.
}}
- if (drm_dp_mst_atomic_check(state))
return false;
ret = drm_dp_mst_atomic_check(state);
if (ret != 0)
return ret;/* Optimize degree of compression */ if (!increase_dsc_bpp(state, mst_state, dc_link, params, vars, count,
k))
return false;
return -ENOSPC;if (!try_disable_dsc(state, dc_link, params, vars, count, k))
return false;
return -ENOSPC;set_dsc_configs_from_fairness_vars(params, vars, count, k);
- return true;
- return 0;
}
static bool is_dsc_need_re_compute( @@ -1087,15 +1091,16 @@ static bool is_dsc_need_re_compute( return is_dsc_need_re_compute; }
-bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars)+int compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars){ int i, j; struct dc_stream_state *stream; bool computed_streams[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; int link_vars_start_index = 0;
int ret = 0;
for (i = 0; i < dc_state->stream_count; i++) computed_streams[i] = false;
@@ -1118,17 +1123,19 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, continue;
if (dcn20_remove_stream_from_ctx(stream->ctx->dc,dc_state, stream) != DC_OK)
return false;
return -EINVAL;if (!is_dsc_need_re_compute(state, dc_state, stream->link)) continue;
mutex_lock(&aconnector->mst_mgr.lock);
if (!compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index)) {
ret = compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index);if (ret != 0) { mutex_unlock(&aconnector->mst_mgr.lock);
return false;
return ret;@@ -1143,22 +1150,22 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
if (stream->timing.flags.DSC == 1) if (dc_stream_add_dsc_to_resource(stream->ctx-dc, dc_state, stream) != DC_OK)
return false;
return -EINVAL;
- return true;
- return ret;
}
-static bool
- pre_compute_mst_dsc_configs_for_state(struct drm_atomic_state
*state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars*vars) +static int pre_compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars*vars) { int i, j; struct dc_stream_state *stream; bool computed_streams[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; int link_vars_start_index = 0;
int ret;
for (i = 0; i < dc_state->stream_count; i++) computed_streams[i] = false;
@@ -1184,13 +1191,12 @@ static bool continue;
mutex_lock(&aconnector->mst_mgr.lock);
if (!compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index)) {mutex_unlock(&aconnector->mst_mgr.lock);return false;}
ret = compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index);mutex_unlock(&aconnector->mst_mgr.lock);
if (ret != 0)return ret;for (j = 0; j < dc_state->stream_count; j++) { if (dc_state->streams[j]->link == stream->link) @@ -
1198,7 +1204,7 @@ static bool } }
- return true;
- return ret;
}
static int find_crtc_index_in_state_by_stream(struct drm_atomic_state *state, @@ -1253,9 +1259,9 @@ static bool is_dsc_precompute_needed(struct drm_atomic_state *state) return ret; }
-bool pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars)+int pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars){ int i; struct dm_atomic_state *dm_state; @@ -1264,11 +1270,12 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
if (!is_dsc_precompute_needed(state)) { DRM_INFO_ONCE("DSC precompute is not needed.\n");
return true;
return 0;
- if (dm_atomic_get_state(state, dm_state_ptr)) {
- ret = dm_atomic_get_state(state, dm_state_ptr);
- if (ret != 0) { DRM_INFO_ONCE("dm_atomic_get_state() failed\n");
return false;
return ret;@@ -1280,7 +1287,7 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
local_dc_state = kmemdup(dm_state->context, sizeof(struct dc_state), GFP_KERNEL); if (!local_dc_state)
return false;
return -ENOMEM;for (i = 0; i < local_dc_state->stream_count; i++) { struct dc_stream_state *stream = dm_state->context-
streams[i]; @@ -1316,9 +1323,9 @@ bool pre_validate_dsc(struct
drm_atomic_state *state, if (ret != 0) goto clean_exit;
- if (!pre_compute_mst_dsc_configs_for_state(state, local_dc_state,
vars)) {
- ret = pre_compute_mst_dsc_configs_for_state(state, local_dc_state,
vars);
if (ret != 0) {
DRM_INFO_ONCE("pre_compute_mst_dsc_configs_for_state()
failed\n");
ret = -EINVAL;@@ -1349,7 +1356,7 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
kfree(local_dc_state);
- return (ret == 0);
- return ret;
}
static unsigned int kbps_from_pbn(unsigned int pbn) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h index b92a7c5671aa2..97fd70df531bf 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h @@ -53,15 +53,15 @@ struct dsc_mst_fairness_vars { struct amdgpu_dm_connector *aconnector; };
-bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars);+int compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars);bool needs_dsc_aux_workaround(struct dc_link *link);
-bool pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars);+int pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars);enum dc_status dm_dp_mst_is_port_support_mode( struct amdgpu_dm_connector *aconnector, -- 2.37.3
--- Regards, Wayne Lin
On Wed, 2022-11-09 at 09:48 +0000, Lin, Wayne wrote:
[Public]
Thanks, Lyude! Comments inline.
-----Original Message----- From: Lyude Paul lyude@redhat.com Sent: Saturday, November 5, 2022 7:59 AM To: amd-gfx@lists.freedesktop.org Cc: Wentland, Harry Harry.Wentland@amd.com; stable@vger.kernel.org; Li, Sun peng (Leo) Sunpeng.Li@amd.com; Siqueira, Rodrigo Rodrigo.Siqueira@amd.com; Deucher, Alexander Alexander.Deucher@amd.com; Koenig, Christian Christian.Koenig@amd.com; Pan, Xinhui Xinhui.Pan@amd.com; David Airlie airlied@gmail.com; Daniel Vetter daniel@ffwll.ch; Kazlauskas, Nicholas Nicholas.Kazlauskas@amd.com; Pillai, Aurabindo Aurabindo.Pillai@amd.com; Li, Roman Roman.Li@amd.com; Zuo, Jerry Jerry.Zuo@amd.com; Wu, Hersen hersenxs.wu@amd.com; Lin, Wayne Wayne.Lin@amd.com; Thomas Zimmermann tzimmermann@suse.de; Mahfooz, Hamza Hamza.Mahfooz@amd.com; Hung, Alex Alex.Hung@amd.com; Francis, David David.Francis@amd.com; Mikita Lipski mikita.lipski@amd.com; Liu, Wenjing Wenjing.Liu@amd.com; open list:DRM DRIVERS dri-devel@lists.freedesktop.org; open list <linux- kernel@vger.kernel.org> Subject: [PATCH 1/2] drm/amdgpu/mst: Stop ignoring error codes and deadlocking
It appears that amdgpu makes the mistake of completely ignoring the return values from the DP MST helpers, and instead just returns a simple true/false. In this case, it seems to have come back to bite us because as a result of simply returning false from compute_mst_dsc_configs_for_state(), amdgpu had no way of telling when a deadlock happened from these helpers. This could definitely result in some kernel splats.
Signed-off-by: Lyude Paul lyude@redhat.com Fixes: 8c20a1ed9b4f ("drm/amd/display: MST DSC compute fair share") Cc: Harry Wentland harry.wentland@amd.com Cc: stable@vger.kernel.org # v5.6+
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 18 +-- .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 107 ++++++++++------ -- .../display/amdgpu_dm/amdgpu_dm_mst_types.h | 12 +- 3 files changed, 73 insertions(+), 64 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 0db2a88cd4d7b..6f76b2c84cdb5 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -6462,7 +6462,7 @@ static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state, struct drm_connector_state *new_con_state; struct amdgpu_dm_connector *aconnector; struct dm_connector_state *dm_conn_state;
- int i, j;
int i, j, ret; int vcpi, pbn_div, pbn, slot_num = 0;
for_each_new_connector_in_state(state, connector,
new_con_state, i) { @@ -6509,8 +6509,11 @@ static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state, dm_conn_state->pbn = pbn; dm_conn_state->vcpi_slots = slot_num;
drm_dp_mst_atomic_enable_dsc(state, aconnector-port, dm_conn_state->pbn,
false);
ret = drm_dp_mst_atomic_enable_dsc(state,aconnector->port,
dm_conn_state-pbn, false);
if (ret != 0)return ret;continue;@@ -9523,10 +9526,9 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
#if defined(CONFIG_DRM_AMD_DC_DCN) if (dc_resource_is_dsc_encoding_supported(dc)) {
if (!pre_validate_dsc(state, &dm_state, vars)) {ret = -EINVAL;
ret = pre_validate_dsc(state, &dm_state, vars);if (ret != 0) goto fail;
}#endif
@@ -9621,9 +9623,9 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev, }
#if defined(CONFIG_DRM_AMD_DC_DCN)
if (!compute_mst_dsc_configs_for_state(state, dm_state-context, vars)) {
ret = compute_mst_dsc_configs_for_state(state, dm_state-context, vars);
if (ret) {DRM_DEBUG_DRIVER("compute_mst_dsc_configs_for_state()
failed\n");
ret = -EINVAL; goto fail;diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c index 6ff96b4bdda5c..30bc2e5058b70 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c @@ -864,25 +864,25 @@ static bool try_disable_dsc(struct drm_atomic_state *state, return true; }
-static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dc_link *dc_link,struct dsc_mst_fairness_vars *vars,struct drm_dp_mst_topology_mgr*mgr,
int *link_vars_start_index)+static int compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dc_link *dc_link,struct dsc_mst_fairness_vars *vars,struct drm_dp_mst_topology_mgr*mgr,
int *link_vars_start_index){ struct dc_stream_state *stream; struct dsc_mst_fairness_params params[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; struct drm_dp_mst_topology_state *mst_state = drm_atomic_get_mst_topology_state(state, mgr); int count = 0;
- int i, k;
int i, k, ret; bool debugfs_overwrite = false;
memset(params, 0, sizeof(params));
if (IS_ERR(mst_state))
return false;
return PTR_ERR(mst_state);mst_state->pbn_div = dm_mst_get_pbn_divider(dc_link); #if
defined(CONFIG_DRM_AMD_DC_DCN) @@ -933,7 +933,7 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
if (count == 0) { ASSERT(0);
return true;
return 0;}
/* k is start index of vars for current phy link used by mst hub */ @@
-949,11 +949,14 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, vars[i + k].bpp_x16 = 0; if (drm_dp_atomic_find_time_slots(state, params[i].port-
mgr, params[i].port,
vars[i + k].pbn) < 0)
return false;
return -EINVAL;Should we also return the error code get from drm_dp_atomic_find_time_slots() rather than assigning a new one here?
Yes we should, nice catch!
}
- if (!drm_dp_mst_atomic_check(state) && !debugfs_overwrite) {
- ret = drm_dp_mst_atomic_check(state);
- if (ret == 0 && !debugfs_overwrite) { set_dsc_configs_from_fairness_vars(params, vars, count, k);
return true;
return 0;- } else if (ret == -EDEADLK) {
return ret;I think we should return here whenever there is an error. Not just for EDEADLK case.
sgtm
}
/* Try max compression */ @@ -964,29 +967,30 @@ static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state, vars[i + k].bpp_x16 = params[i].bw_range.min_target_bpp_x16; if (drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, vars[i
- k].pbn) < 0)
return false;
return -EINVAL;Same as above.
} else { vars[i + k].pbn =kbps_to_peak_pbn(params[i].bw_range.stream_kbps); vars[i + k].dsc_enabled = false; vars[i + k].bpp_x16 = 0; if (drm_dp_atomic_find_time_slots(state, params[i].port->mgr, params[i].port, vars[i
- k].pbn) < 0)
return false;
return -EINVAL;Same as above.
}}
- if (drm_dp_mst_atomic_check(state))
return false;
ret = drm_dp_mst_atomic_check(state);
if (ret != 0)
return ret;/* Optimize degree of compression */ if (!increase_dsc_bpp(state, mst_state, dc_link, params, vars, count,
k))
return false;
return -ENOSPC;if (!try_disable_dsc(state, dc_link, params, vars, count, k))
return false;
return -ENOSPC;set_dsc_configs_from_fairness_vars(params, vars, count, k);
- return true;
- return 0;
}
static bool is_dsc_need_re_compute( @@ -1087,15 +1091,16 @@ static bool is_dsc_need_re_compute( return is_dsc_need_re_compute; }
-bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars)+int compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars){ int i, j; struct dc_stream_state *stream; bool computed_streams[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; int link_vars_start_index = 0;
int ret = 0;
for (i = 0; i < dc_state->stream_count; i++) computed_streams[i] = false;
@@ -1118,17 +1123,19 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state, continue;
if (dcn20_remove_stream_from_ctx(stream->ctx->dc,dc_state, stream) != DC_OK)
return false;
return -EINVAL;if (!is_dsc_need_re_compute(state, dc_state, stream->link)) continue;
mutex_lock(&aconnector->mst_mgr.lock);
if (!compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index)) {
ret = compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index);if (ret != 0) { mutex_unlock(&aconnector->mst_mgr.lock);
return false;
return ret;@@ -1143,22 +1150,22 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
if (stream->timing.flags.DSC == 1) if (dc_stream_add_dsc_to_resource(stream->ctx-dc, dc_state, stream) != DC_OK)
return false;
return -EINVAL;
- return true;
- return ret;
}
-static bool
- pre_compute_mst_dsc_configs_for_state(struct drm_atomic_state
*state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars*vars) +static int pre_compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars*vars) { int i, j; struct dc_stream_state *stream; bool computed_streams[MAX_PIPES]; struct amdgpu_dm_connector *aconnector; int link_vars_start_index = 0;
int ret;
for (i = 0; i < dc_state->stream_count; i++) computed_streams[i] = false;
@@ -1184,13 +1191,12 @@ static bool continue;
mutex_lock(&aconnector->mst_mgr.lock);
if (!compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index)) {mutex_unlock(&aconnector->mst_mgr.lock);return false;}
ret = compute_mst_dsc_configs_for_link(state, dc_state,stream->link, vars,
&aconnector->mst_mgr,&link_vars_start_index);mutex_unlock(&aconnector->mst_mgr.lock);
if (ret != 0)return ret;for (j = 0; j < dc_state->stream_count; j++) { if (dc_state->streams[j]->link == stream->link) @@ -
1198,7 +1204,7 @@ static bool } }
- return true;
- return ret;
}
static int find_crtc_index_in_state_by_stream(struct drm_atomic_state *state, @@ -1253,9 +1259,9 @@ static bool is_dsc_precompute_needed(struct drm_atomic_state *state) return ret; }
-bool pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars)+int pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars){ int i; struct dm_atomic_state *dm_state; @@ -1264,11 +1270,12 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
if (!is_dsc_precompute_needed(state)) { DRM_INFO_ONCE("DSC precompute is not needed.\n");
return true;
return 0;
- if (dm_atomic_get_state(state, dm_state_ptr)) {
- ret = dm_atomic_get_state(state, dm_state_ptr);
- if (ret != 0) { DRM_INFO_ONCE("dm_atomic_get_state() failed\n");
return false;
return ret;@@ -1280,7 +1287,7 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
local_dc_state = kmemdup(dm_state->context, sizeof(struct dc_state), GFP_KERNEL); if (!local_dc_state)
return false;
return -ENOMEM;for (i = 0; i < local_dc_state->stream_count; i++) { struct dc_stream_state *stream = dm_state->context-
streams[i]; @@ -1316,9 +1323,9 @@ bool pre_validate_dsc(struct
drm_atomic_state *state, if (ret != 0) goto clean_exit;
- if (!pre_compute_mst_dsc_configs_for_state(state, local_dc_state,
vars)) {
- ret = pre_compute_mst_dsc_configs_for_state(state, local_dc_state,
vars);
if (ret != 0) {
DRM_INFO_ONCE("pre_compute_mst_dsc_configs_for_state()
failed\n");
ret = -EINVAL;@@ -1349,7 +1356,7 @@ bool pre_validate_dsc(struct drm_atomic_state *state,
kfree(local_dc_state);
- return (ret == 0);
- return ret;
}
static unsigned int kbps_from_pbn(unsigned int pbn) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h index b92a7c5671aa2..97fd70df531bf 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h @@ -53,15 +53,15 @@ struct dsc_mst_fairness_vars { struct amdgpu_dm_connector *aconnector; };
-bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars);+int compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
struct dc_state *dc_state,struct dsc_mst_fairness_vars *vars);bool needs_dsc_aux_workaround(struct dc_link *link);
-bool pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars);+int pre_validate_dsc(struct drm_atomic_state *state,
struct dm_atomic_state **dm_state_ptr,struct dsc_mst_fairness_vars *vars);enum dc_status dm_dp_mst_is_port_support_mode( struct amdgpu_dm_connector *aconnector, -- 2.37.3
Regards, Wayne Lin
On Wed, 2022-11-09 at 09:48 +0000, Lin, Wayne wrote:
}
- if (!drm_dp_mst_atomic_check(state) && !debugfs_overwrite) {
- ret = drm_dp_mst_atomic_check(state);
- if (ret == 0 && !debugfs_overwrite) {
set_dsc_configs_from_fairness_vars(params, vars, count, k);
return true;
return 0;- } else if (ret == -EDEADLK) {
return ret;I think we should return here whenever there is an error. Not just for EDEADLK case.
Are we sure about this one? I think we may actually want to make this so it returns on ret != -ENOSPC, since we want the function to continue if there's no space in the atomic state available so it can try recomputing things with compression enabled. On ret == 0 it should return early without doing compression, and on ret == -ENOSPC it should just continue the function from there
[Public]
-----Original Message----- From: Lyude Paul lyude@redhat.com Sent: Tuesday, November 15, 2022 5:55 AM To: Lin, Wayne Wayne.Lin@amd.com; amd-gfx@lists.freedesktop.org Cc: Wentland, Harry Harry.Wentland@amd.com; stable@vger.kernel.org; Li, Sun peng (Leo) Sunpeng.Li@amd.com; Siqueira, Rodrigo Rodrigo.Siqueira@amd.com; Deucher, Alexander Alexander.Deucher@amd.com; Koenig, Christian Christian.Koenig@amd.com; Pan, Xinhui Xinhui.Pan@amd.com; David Airlie airlied@gmail.com; Daniel Vetter daniel@ffwll.ch; Kazlauskas, Nicholas Nicholas.Kazlauskas@amd.com; Pillai, Aurabindo Aurabindo.Pillai@amd.com; Li, Roman Roman.Li@amd.com; Zuo, Jerry Jerry.Zuo@amd.com; Wu, Hersen hersenxs.wu@amd.com; Thomas Zimmermann tzimmermann@suse.de; Mahfooz, Hamza Hamza.Mahfooz@amd.com; Hung, Alex Alex.Hung@amd.com; Francis, David David.Francis@amd.com; Mikita Lipski mikita.lipski@amd.com; Liu, Wenjing Wenjing.Liu@amd.com; open list:DRM DRIVERS <dri- devel@lists.freedesktop.org>; open list linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] drm/amdgpu/mst: Stop ignoring error codes and deadlocking
On Wed, 2022-11-09 at 09:48 +0000, Lin, Wayne wrote:
}
- if (!drm_dp_mst_atomic_check(state) && !debugfs_overwrite) {
- ret = drm_dp_mst_atomic_check(state);
- if (ret == 0 && !debugfs_overwrite) {
set_dsc_configs_from_fairness_vars(params, vars, count, k);
return true;
return 0;- } else if (ret == -EDEADLK) {
return ret;I think we should return here whenever there is an error. Not just for EDEADLK case.
Are we sure about this one? I think we may actually want to make this so it returns on ret != -ENOSPC, since we want the function to continue if there's no space in the atomic state available so it can try recomputing things with compression enabled. On ret == 0 it should return early without doing compression, and on ret == -ENOSPC it should just continue the function from there
Oh, right.. Thanks for saving me from causing disaster : )
-- Cheers, Lyude Paul (she/her) Software Engineer at Red Hat
-- Regards, Wayne
linux-stable-mirror@lists.linaro.org
-
Lin, Wayne -
Lyude Paul