Re: [PATCH] drm/amd/display: Ignore First MST Sideband Message Return Error

On 7/11/2022 16:52, Rodrigo Siqueira wrote:

From: Fangzhi Zuo Jerry.Zuo@amd.com

[why] The first MST sideband message returns AUX_RET_ERROR_HPD_DISCON on a certain Intel platform. Aux transaction is considered a failure if HPD unexpectedly pulled low. The actual aux transaction success in such case, hence do not return an error. Several Dell Intel-based Precision systems had this issue, for example, Precision 3260 and 3460.

[how] Not returning error when AUX_RET_ERROR_HPD_DISCON detected on the first sideband message.

Cc: Harry Wentland harry.wentland@amd.com Cc: Mario Limonciello mario.limonciello@amd.com Cc: Qian Fu Qian.Fu@dell.com Cc: stable@vger.kernel.org Signed-off-by: Fangzhi Zuo Jerry.Zuo@amd.com

---

.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 27 +++++++++++++++++++ .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h | 8 ++++++ .../display/amdgpu_dm/amdgpu_dm_mst_types.c | 17 ++++++++++++ 3 files changed, 52 insertions(+)

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 de1c139ae279..e0af3d003b5c 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -72,6 +72,7 @@ #include <linux/pci.h> #include <linux/firmware.h> #include <linux/component.h> +#include <linux/dmi.h> #include <drm/drm_atomic.h> #include <drm/drm_atomic_uapi.h> @@ -1400,6 +1401,29 @@ static bool dm_should_disable_stutter(struct pci_dev *pdev) return false; } +static const struct dmi_system_id hpd_disconnect_quirk_table[] = {

• {

• .matches = {
  

• 	DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
  

• 	DMI_MATCH(DMI_PRODUCT_NAME, "Precision 3660"),
  

• },
  

• },

I think two more matches are needed here for the other two products that are affected by this.

• {}

+};

+void retrieve_dmi_info(struct amdgpu_display_manager *dm) +{

• const struct dmi_system_id *dmi_id;
• dm->aux_hpd_discon_quirk = false;
• dmi_id = dmi_first_match(hpd_disconnect_quirk_table);
• if (dmi_id) {

• dm->aux_hpd_discon_quirk = true;
  

• DRM_INFO("aux_hpd_discon_quirk attached\n");
  

• }

+}

• static int amdgpu_dm_init(struct amdgpu_device *adev) { struct dc_init_data init_data;

@@ -1528,6 +1552,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev) init_data.flags.enable_mipi_converter_optimization = true; INIT_LIST_HEAD(&adev->dm.da_list);

• retrieve_dmi_info(&adev->dm);
• /* Display Core create. */ adev->dm.dc = dc_create(&init_data);

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h index e04e6b3f609f..33d66d4897dc 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h @@ -547,6 +547,14 @@ struct amdgpu_display_manager { * last successfully applied backlight values. */ u32 actual_brightness[AMDGPU_DM_MAX_NUM_EDP];

• /**

• * @aux_hpd_discon_quirk:
  

• *
  

• * quirk for hpd discon while aux is on-going.
  

• * occurred on certain intel platform
  

• */
  

• bool aux_hpd_discon_quirk; };

enum dsc_clock_force_state { 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 8237029cedf5..168d5676b657 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 @@ -56,6 +56,8 @@ static ssize_t dm_dp_aux_transfer(struct drm_dp_aux *aux, ssize_t result = 0; struct aux_payload payload; enum aux_return_code_type operation_result;

• struct amdgpu_device *adev;
• struct ddc_service *ddc;

if (WARN_ON(msg->size > 16)) return -E2BIG; @@ -74,6 +76,21 @@ static ssize_t dm_dp_aux_transfer(struct drm_dp_aux *aux, result = dc_link_aux_transfer_raw(TO_DM_AUX(aux)->ddc_service, &payload, &operation_result);

• /*

• * w/a on certain intel platform where hpd is unexpected to pull low during
  

• * 1st sideband message transaction by return AUX_RET_ERROR_HPD_DISCON
  

• * aux transaction is succuess in such case, therefore bypass the error
  

• */
  

• ddc = TO_DM_AUX(aux)->ddc_service;
• adev = ddc->ctx->driver_context;
• if (adev->dm.aux_hpd_discon_quirk) {

• if (msg->address == DP_SIDEBAND_MSG_DOWN_REQ_BASE &&
  

• 	operation_result == AUX_RET_ERROR_HPD_DISCON) {
  

• 	result = 0;
  

• 	operation_result = AUX_RET_SUCCESS;
  

• }
  

• }
• if (payload.write && result >= 0) result = msg->size;