The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x e6861d8264cd43c5eb20196e53df36fd71ec5698 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023121841-backspin-troubling-44cf@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
e6861d8264cd ("drm/i915/edp: don't write to DP_LINK_BW_SET when using rate select") 3072a24c778a ("drm/i915: Introduce crtc_state->enhanced_framing") 3dfeb80b3088 ("drm/i915: Fix FEC state dump")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From e6861d8264cd43c5eb20196e53df36fd71ec5698 Mon Sep 17 00:00:00 2001 From: Jani Nikula jani.nikula@intel.com Date: Tue, 5 Dec 2023 20:05:51 +0200 Subject: [PATCH] drm/i915/edp: don't write to DP_LINK_BW_SET when using rate select MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
The eDP 1.5 spec adds a clarification for eDP 1.4x:
For eDP v1.4x, if the Source device chooses the Main-Link rate by way of DPCD 00100h, the Sink device shall ignore DPCD 00115h[2:0].
We write 0 to DP_LINK_BW_SET (DPCD 100h) even when using DP_LINK_RATE_SET (DPCD 114h). Stop doing that, as it can cause the panel to ignore the rate set method.
Moreover, 0 is a reserved value for DP_LINK_BW_SET, and should not be used.
v2: Improve the comments (Ville)
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9081 Tested-by: Animesh Manna animesh.manna@intel.com Reviewed-by: Uma Shankar uma.shankar@intel.com Cc: Ville Syrjälä ville.syrjala@linux.intel.com Signed-off-by: Jani Nikula jani.nikula@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20231205180551.2476228-1-jani.... (cherry picked from commit 23b392b94acb0499f69706c5808c099f590ebcf4) Cc: stable@vger.kernel.org Signed-off-by: Jani Nikula jani.nikula@intel.com
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c index dbc1b66c8ee4..1abfafbbfa75 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c @@ -650,19 +650,30 @@ intel_dp_update_link_bw_set(struct intel_dp *intel_dp, const struct intel_crtc_state *crtc_state, u8 link_bw, u8 rate_select) { - u8 link_config[2]; + u8 lane_count = crtc_state->lane_count;
- /* Write the link configuration data */ - link_config[0] = link_bw; - link_config[1] = crtc_state->lane_count; if (crtc_state->enhanced_framing) - link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; - drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2); + lane_count |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
- /* eDP 1.4 rate select method. */ - if (!link_bw) - drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET, - &rate_select, 1); + if (link_bw) { + /* DP and eDP v1.3 and earlier link bw set method. */ + u8 link_config[] = { link_bw, lane_count }; + + drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, + ARRAY_SIZE(link_config)); + } else { + /* + * eDP v1.4 and later link rate set method. + * + * eDP v1.4x sinks shall ignore DP_LINK_RATE_SET if + * DP_LINK_BW_SET is set. Avoid writing DP_LINK_BW_SET. + * + * eDP v1.5 sinks allow choosing either, and the last choice + * shall be active. + */ + drm_dp_dpcd_writeb(&intel_dp->aux, DP_LANE_COUNT_SET, lane_count); + drm_dp_dpcd_writeb(&intel_dp->aux, DP_LINK_RATE_SET, rate_select); + } }
/*