On Mon, 24 Oct 2016, Imre Deak <imre.deak@xxxxxxxxx> wrote: > On my APL the LSPCON firmware resumes in PCON mode as opposed to the > expected LS mode. It also appears to be in a state where AUX DPCD reads > will succeed but return garbage recovering only after a few hundreds of > milliseconds. After the recovery time DPCD reads will result in the > correct values and things will continue to work. If I2C over AUX is > attempted during this recovery time (implying an AUX write transaction) > the firmware won't recover and will stay in this broken state. > > As a workaround check if the firmware is in PCON state after resume and > if so wait until the correct DPCD values are returned. For this we > compare the branch descriptor with the one we cached during init time. > If the firmware was in the LS state, we skip the w/a and continue as > before. > > v2: > - Use the DP descriptor value cached in intel_dp. (Jani) > - Get to intel_dp using container_of(), instead of a cached ptr. > (Shashank) > - Use usleep_range() instead of msleep(). > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98353 > Cc: Shashank Sharma <shashank.sharma@xxxxxxxxx> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Cc: Jani Nikula <jani.nikula@xxxxxxxxx> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> I don't think we properly understand what's going on with the device. In the mean time, limp on with this if this fixes stuff. Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_dp.c | 2 +- > drivers/gpu/drm/i915/intel_drv.h | 3 +++ > drivers/gpu/drm/i915/intel_lspcon.c | 37 ++++++++++++++++++++++++++++++++++++- > 3 files changed, 40 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > index 043993f..e9be955 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -1451,7 +1451,7 @@ static void intel_dp_print_rates(struct intel_dp *intel_dp) > DRM_DEBUG_KMS("common rates: %s\n", str); > } > > -static bool > +bool > __intel_dp_read_desc(struct intel_dp *intel_dp, struct intel_dp_desc *desc) > { > u32 base = drm_dp_is_branch(intel_dp->dpcd) ? DP_BRANCH_OUI : > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h > index 45f55b5..f2b6c59 100644 > --- a/drivers/gpu/drm/i915/intel_drv.h > +++ b/drivers/gpu/drm/i915/intel_drv.h > @@ -974,6 +974,7 @@ struct intel_dp { > struct intel_lspcon { > bool active; > enum drm_lspcon_mode mode; > + bool desc_valid; > }; > > struct intel_digital_port { > @@ -1461,6 +1462,8 @@ static inline unsigned int intel_dp_unused_lane_mask(int lane_count) > } > > bool intel_dp_read_dpcd(struct intel_dp *intel_dp); > +bool __intel_dp_read_desc(struct intel_dp *intel_dp, > + struct intel_dp_desc *desc); > bool intel_dp_read_desc(struct intel_dp *intel_dp); > > /* intel_dp_aux_backlight.c */ > diff --git a/drivers/gpu/drm/i915/intel_lspcon.c b/drivers/gpu/drm/i915/intel_lspcon.c > index 3dc5a0b..daa5234 100644 > --- a/drivers/gpu/drm/i915/intel_lspcon.c > +++ b/drivers/gpu/drm/i915/intel_lspcon.c > @@ -97,8 +97,43 @@ static bool lspcon_probe(struct intel_lspcon *lspcon) > return true; > } > > +static void lspcon_resume_in_pcon_wa(struct intel_lspcon *lspcon) > +{ > + struct intel_dp *intel_dp = lspcon_to_intel_dp(lspcon); > + unsigned long start = jiffies; > + > + if (!lspcon->desc_valid) > + return; > + > + while (1) { > + struct intel_dp_desc desc; > + > + /* > + * The w/a only applies in PCON mode and we don't expect any > + * AUX errors. > + */ > + if (!__intel_dp_read_desc(intel_dp, &desc)) > + return; > + > + if (!memcmp(&intel_dp->desc, &desc, sizeof(desc))) { > + DRM_DEBUG_KMS("LSPCON recovering in PCON mode after %u ms\n", > + jiffies_to_msecs(jiffies - start)); > + return; > + } > + > + if (time_after(jiffies, start + msecs_to_jiffies(1000))) > + break; > + > + usleep_range(10000, 15000); > + } > + > + DRM_DEBUG_KMS("LSPCON DP descriptor mismatch after resume\n"); > +} > + > void lspcon_resume(struct intel_lspcon *lspcon) > { > + lspcon_resume_in_pcon_wa(lspcon); > + > if (lspcon_change_mode(lspcon, DRM_LSPCON_MODE_PCON, true)) > DRM_ERROR("LSPCON resume failed\n"); > else > @@ -143,7 +178,7 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port) > return false; > } > > - intel_dp_read_desc(dp); > + lspcon->desc_valid = intel_dp_read_desc(dp); > > DRM_DEBUG_KMS("Success: LSPCON init\n"); > return true; -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
