On Wed, Jan 15, 2025 at 3:10 AM Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote: > > On Tue, 14 Jan 2025, Jonathan Denose <jdenose@xxxxxxxxxx> wrote: > > The display on the Advantech UTC124G3PWWW0E-ES worked fine until commit > > "drm/i915/dp: Recheck link state after modeset" was introduced. After > > this commit the display flickers intermittently as the driver code > > initiates the delayed link recheck in an infinite loop. > > > > To resolve this issue for the Advantech device, add a quirk to skip over > > the delayed link recheck. > > It would be better to try to get at the root cause first, instead of > blindly skipping required parts. The code's complicated enough without > quirks, and removing them afterwards is very difficult. > > Please file a bug according to [1], and attach full dmesg with debugs > enabled. I filed a bug with the full dmesg a few weeks ago: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13344 > Cc: Imre > > BR, > Jani. > > > > [1] https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.html > > > > > > > Signed-off-by: Jonathan Denose <jdenose@xxxxxxxxxx> > > --- > > > > drivers/gpu/drm/i915/display/intel_dp_link_training.c | 4 +++- > > drivers/gpu/drm/i915/display/intel_quirks.c | 8 ++++++++ > > drivers/gpu/drm/i915/display/intel_quirks.h | 1 + > > 3 files changed, 12 insertions(+), 1 deletion(-) > > > > 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 397cc4ebae526..7804ad38b00cd 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c > > @@ -32,6 +32,7 @@ > > #include "intel_encoder.h" > > #include "intel_hotplug.h" > > #include "intel_panel.h" > > +#include "intel_quirks.h" > > > > #define LT_MSG_PREFIX "[CONNECTOR:%d:%s][ENCODER:%d:%s][%s] " > > #define LT_MSG_ARGS(_intel_dp, _dp_phy) (_intel_dp)->attached_connector->base.base.id, \ > > @@ -1622,7 +1623,8 @@ void intel_dp_start_link_train(struct intel_atomic_state *state, > > lt_dbg(intel_dp, DP_PHY_DPRX, "Forcing link training failure\n"); > > } else if (passed) { > > intel_dp->link.seq_train_failures = 0; > > - intel_encoder_link_check_queue_work(encoder, 2000); > > + if (!intel_has_quirk(display, QUIRK_SKIP_LINK_CHECK)) > > + intel_encoder_link_check_queue_work(encoder, 2000); > > return; > > } > > > > diff --git a/drivers/gpu/drm/i915/display/intel_quirks.c b/drivers/gpu/drm/i915/display/intel_quirks.c > > index 28f497ae785bb..d472a5f21f8b9 100644 > > --- a/drivers/gpu/drm/i915/display/intel_quirks.c > > +++ b/drivers/gpu/drm/i915/display/intel_quirks.c > > @@ -78,6 +78,12 @@ static void quirk_fw_sync_len(struct intel_dp *intel_dp) > > drm_info(display->drm, "Applying Fast Wake sync pulse count quirk\n"); > > } > > > > +static void quirk_skip_link_check(struct intel_display *display) > > +{ > > + intel_set_quirk(display, QUIRK_SKIP_LINK_CHECK); > > + drm_info(display->drm, "Applying skip link check quirk\n"); > > +} > > + > > struct intel_quirk { > > int device; > > int subsystem_vendor; > > @@ -229,6 +235,8 @@ static struct intel_quirk intel_quirks[] = { > > { 0x3184, 0x1019, 0xa94d, quirk_increase_ddi_disabled_time }, > > /* HP Notebook - 14-r206nv */ > > { 0x0f31, 0x103c, 0x220f, quirk_invert_brightness }, > > + /* Advantech UTC124G3PWWW0E-ES */ > > + {0x5a85, 0x8086, 0x2212, quirk_skip_link_check}, > > }; > > > > static const struct intel_dpcd_quirk intel_dpcd_quirks[] = { > > diff --git a/drivers/gpu/drm/i915/display/intel_quirks.h b/drivers/gpu/drm/i915/display/intel_quirks.h > > index cafdebda75354..9e8f2816a4fba 100644 > > --- a/drivers/gpu/drm/i915/display/intel_quirks.h > > +++ b/drivers/gpu/drm/i915/display/intel_quirks.h > > @@ -20,6 +20,7 @@ enum intel_quirk_id { > > QUIRK_LVDS_SSC_DISABLE, > > QUIRK_NO_PPS_BACKLIGHT_POWER_HOOK, > > QUIRK_FW_SYNC_LEN, > > + QUIRK_SKIP_LINK_CHECK, > > }; > > > > void intel_init_quirks(struct intel_display *display); > > -- > Jani Nikula, Intel -- Jonathan
