[PATCH v4 4/8] drm/i915/dp: Track source OUI validity explicitly
Ville Syrjälä
ville.syrjala at intel.com
Fri Oct 25 07:18:47 UTC 2024
On Wed, Oct 23, 2024 at 05:40:56PM +0300, Imre Deak wrote:
> On Wed, Oct 23, 2024 at 03:16:11PM +0300, Ville Syrjälä wrote:
> > On Tue, Oct 22, 2024 at 12:46:23PM +0300, Imre Deak wrote:
> > > While updating the source OUI on the sink the driver should avoid
> > > writing the OUI if it's already up-to-date to prevent the sink from
> > > resetting itself in response to the update. On eDP - the only output
> > > type where the OUI was updated so far - the driver ensured this by
> > > comparing the current source OUI DPCD register values with the expected
> > > Intel OUI value, skipping the update in case of a match. On some non-eDP
> > > sinks - at least on Synaptics branch devices - this method doesn't work,
> > > since the source OUI DPCD registers read back as all 0, even after
> > > updating the registers.
> > >
> > > Handle the above kind of sinks by tracking when the OUI was updated and
> > > so should be valid, regardless of what the DPCD registers contain.
> > >
> > > eDP sinks reset the written source OUI value when the panel power is
> > > disabled, invalidate the OUI state accordingly.
> > >
> > > This is required by a follow-up patch updating the source OUI for
> > > non-eDP sink types as well.
> > >
> > > v2: Fix setting intel_dp::oui_valid=true, if the DPCD register contains
> > > already the expected value.
> > >
> > > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > > ---
> > > drivers/gpu/drm/i915/display/g4x_dp.c | 1 +
> > > drivers/gpu/drm/i915/display/intel_ddi.c | 1 +
> > > .../drm/i915/display/intel_display_types.h | 1 +
> > > drivers/gpu/drm/i915/display/intel_dp.c | 38 ++++++++++++-------
> > > drivers/gpu/drm/i915/display/intel_dp.h | 1 +
> > > drivers/gpu/drm/i915/display/intel_pps.c | 6 ++-
> > > 6 files changed, 34 insertions(+), 14 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/g4x_dp.c b/drivers/gpu/drm/i915/display/g4x_dp.c
> > > index 440fb3002f286..596e926ef0894 100644
> > > --- a/drivers/gpu/drm/i915/display/g4x_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/g4x_dp.c
> > > @@ -1251,6 +1251,7 @@ static void intel_dp_encoder_reset(struct drm_encoder *encoder)
> > > intel_dp->DP = intel_de_read(display, intel_dp->output_reg);
> > >
> > > intel_dp->reset_link_params = true;
> > > + intel_dp_invalidate_source_oui(intel_dp);
> > >
> > > if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> > > vlv_pps_pipe_reset(intel_dp);
> > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > > index fe1ded6707f90..465f245a53c48 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > > @@ -4392,6 +4392,7 @@ static void intel_ddi_encoder_reset(struct drm_encoder *encoder)
> > > struct intel_digital_port *dig_port = enc_to_dig_port(to_intel_encoder(encoder));
> > >
> > > intel_dp->reset_link_params = true;
> > > + intel_dp_invalidate_source_oui(intel_dp);
> > >
> > > intel_pps_encoder_reset(intel_dp);
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > index 2bb1fa64da2f1..9b46427806c6d 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > @@ -1765,6 +1765,7 @@ struct intel_dp {
> > >
> > > /* When we last wrote the OUI for eDP */
> > > unsigned long last_oui_write;
> > > + bool oui_valid;
> > >
> > > bool colorimetry_support;
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > > index 96ee5de719a2c..a6f84b8f770d0 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > @@ -3400,33 +3400,46 @@ void intel_dp_sink_disable_decompression(struct intel_atomic_state *state,
> > > }
> > >
> > > static void
> > > -intel_edp_init_source_oui(struct intel_dp *intel_dp, bool careful)
> > > +intel_dp_init_source_oui(struct intel_dp *intel_dp)
> > > {
> > > struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > > u8 oui[] = { 0x00, 0xaa, 0x01 };
> > > u8 buf[3] = {};
> > >
> > > + if (!intel_dp_is_edp(intel_dp))
> > > + return;
> > > +
> > > + if (READ_ONCE(intel_dp->oui_valid))
> > > + return;
> > > +
> > > + WRITE_ONCE(intel_dp->oui_valid, true);
> >
> > Would seem nicer if this is set alognside the timestamp.
> > Are we actually always setting both?
>
> Yes. In case DPCD contained already the correct value, it's not known
> when it was written, so the code assumes it's written now.
>
> > In that case maybe extract both into a small helper?
>
> You mean setting both at the same place, but not sure how it would work:
> I set the flag before writing the register to account for the
> T1: oui_valid=true -> T2: HPD/oui_valid=false -> T1: write DPCD case,
> guaranteeing that oui_valid remains false. OTOH last_oui_write should be
> set after the DPCD write so that the wait duration can't get shorter
> than needed.
OK, a bit ugly but can't see a better non-racy way for it, so
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> > > +
> > > /*
> > > * During driver init, we want to be careful and avoid changing the source OUI if it's
> > > * already set to what we want, so as to avoid clearing any state by accident
> > > */
> > > - if (careful) {
> > > - if (drm_dp_dpcd_read(&intel_dp->aux, DP_SOURCE_OUI, buf, sizeof(buf)) < 0)
> > > - drm_err(&i915->drm, "Failed to read source OUI\n");
> > > + if (drm_dp_dpcd_read(&intel_dp->aux, DP_SOURCE_OUI, buf, sizeof(buf)) < 0)
> > > + drm_err(&i915->drm, "Failed to read source OUI\n");
> > >
> > > - if (memcmp(oui, buf, sizeof(oui)) == 0) {
> > > - /* Assume the OUI was written now. */
> > > - intel_dp->last_oui_write = jiffies;
> > > - return;
> > > - }
> > > + if (memcmp(oui, buf, sizeof(oui)) == 0) {
> > > + /* Assume the OUI was written now. */
> > > + intel_dp->last_oui_write = jiffies;
> > > + return;
> > > }
> > >
> > > - if (drm_dp_dpcd_write(&intel_dp->aux, DP_SOURCE_OUI, oui, sizeof(oui)) < 0)
> > > + if (drm_dp_dpcd_write(&intel_dp->aux, DP_SOURCE_OUI, oui, sizeof(oui)) < 0) {
> > > drm_err(&i915->drm, "Failed to write source OUI\n");
> > > + WRITE_ONCE(intel_dp->oui_valid, false);
> > > + }
> > >
> > > intel_dp->last_oui_write = jiffies;
> > > }
> > >
> > > +void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp)
> > > +{
> > > + WRITE_ONCE(intel_dp->oui_valid, false);
> > > +}
> > > +
> > > void intel_dp_wait_source_oui(struct intel_dp *intel_dp)
> > > {
> > > struct intel_connector *connector = intel_dp->attached_connector;
> > > @@ -3462,8 +3475,7 @@ void intel_dp_set_power(struct intel_dp *intel_dp, u8 mode)
> > > lspcon_resume(dp_to_dig_port(intel_dp));
> > >
> > > /* Write the source OUI as early as possible */
> > > - if (intel_dp_is_edp(intel_dp))
> > > - intel_edp_init_source_oui(intel_dp, false);
> > > + intel_dp_init_source_oui(intel_dp);
> > >
> > > /*
> > > * When turning on, we need to retry for 1ms to give the sink
> > > @@ -4184,7 +4196,7 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp, struct intel_connector *connector
> > > * If needed, program our source OUI so we can make various Intel-specific AUX services
> > > * available (such as HDR backlight controls)
> > > */
> > > - intel_edp_init_source_oui(intel_dp, true);
> > > + intel_dp_init_source_oui(intel_dp);
> > >
> > > return true;
> > > }
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
> > > index 4efb9605a50e0..48f10876be656 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.h
> > > @@ -189,6 +189,7 @@ void intel_dp_check_frl_training(struct intel_dp *intel_dp);
> > > void intel_dp_pcon_dsc_configure(struct intel_dp *intel_dp,
> > > const struct intel_crtc_state *crtc_state);
> > >
> > > +void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp);
> > > void intel_dp_wait_source_oui(struct intel_dp *intel_dp);
> > > int intel_dp_output_bpp(enum intel_output_format output_format, int bpp);
> > >
> > > diff --git a/drivers/gpu/drm/i915/display/intel_pps.c b/drivers/gpu/drm/i915/display/intel_pps.c
> > > index 64f1f7ea94993..3d1f9b17034d0 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_pps.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_pps.c
> > > @@ -861,8 +861,10 @@ static void intel_pps_vdd_off_sync_unlocked(struct intel_dp *intel_dp)
> > > intel_de_read(display, pp_stat_reg),
> > > intel_de_read(display, pp_ctrl_reg));
> > >
> > > - if ((pp & PANEL_POWER_ON) == 0)
> > > + if ((pp & PANEL_POWER_ON) == 0) {
> > > intel_dp->pps.panel_power_off_time = ktime_get_boottime();
> > > + intel_dp_invalidate_source_oui(intel_dp);
> >
> > Hmm. I was thinking the rsulting long HPD would be enough, but I
> > guess we do have at least one example of a machine with no HPD on
> > eDP :(
>
> Ok, didn't think of an HPD getting always generated (is that guaranteed
> vs. only an artifact?) Another reason for doing the above synchronously
> here would be to guarantee that a modeset disabling/reenabling the panel
> power will be guaranteed to see oui_valid=false during reenabling, so
> that reenabling will rewrite the OUI (the HPD might be handled at any
> point wrt. the reenabling).
>
> > > + }
> > >
> > > intel_display_power_put(dev_priv,
> > > intel_aux_power_domain(dig_port),
> > > @@ -1074,6 +1076,8 @@ void intel_pps_off_unlocked(struct intel_dp *intel_dp)
> > > wait_panel_off(intel_dp);
> > > intel_dp->pps.panel_power_off_time = ktime_get_boottime();
> > >
> > > + intel_dp_invalidate_source_oui(intel_dp);
> > > +
> > > /* We got a reference when we enabled the VDD. */
> > > intel_display_power_put(dev_priv,
> > > intel_aux_power_domain(dig_port),
> > > --
> > > 2.44.2
> >
> > --
> > Ville Syrjälä
> > Intel
--
Ville Syrjälä
Intel
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