[PATCH v2 1/3] drm/i915/dp: Initialize the source OUI write timestamp always

[PATCH v2 1/3] drm/i915/dp: Initialize the source OUI write timestamp always

[Imre Deak]

If the source OUI DPCD register value matches the expected Intel OUI
value, the write timestamp doesn't get updated leaving it at the 0
initial value if the OUI wasn't written before. This can lead to an
incorrect wait duration in intel_dp_wait_source_oui(), since jiffies is
not inited to 0 in general (on a 32 bit system INITIAL_JIFFIES is set to
5 minutes ahead of wrap-around). Fix this by intializing the write
timestamp in the above case as well.

Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 16dc1d26d2a25..b7661529f1927 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3349,8 +3349,11 @@ intel_edp_init_source_oui(struct intel_dp *intel_dp, bool 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 (memcmp(oui, buf, sizeof(oui)) == 0)
+		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)
-- 
2.44.2

[PATCH v2 2/3] drm/i915/dp: Track source OUI validity explicitly

[Imre Deak]

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.

This is required by the next patch updating the source OUI on non-eDP
sink types as well.

Signed-off-by: Imre Deak <imre.deak@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       | 25 ++++++++++++++-----
 drivers/gpu/drm/i915/display/intel_dp.h       |  1 +
 5 files changed, 23 insertions(+), 6 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 7ff97e5b83dd5..ad84ffa31c97f 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1757,6 +1757,7 @@ 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 b7661529f1927..2d6ffbeae07a0 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3335,31 +3335,43 @@ 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;
+
 	/*
 	 * 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 (!intel_dp->oui_valid) {
 		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;
+			intel_dp->oui_valid = true;
 		}
 	}
 
+	if (intel_dp->oui_valid)
+		return;
+
 	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");
 
 	intel_dp->last_oui_write = jiffies;
+	intel_dp->oui_valid = true;
+}
+
+void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp)
+{
+	intel_dp->oui_valid = false;
 }
 
 void intel_dp_wait_source_oui(struct intel_dp *intel_dp)
@@ -3390,6 +3402,8 @@ void intel_dp_set_power(struct intel_dp *intel_dp, u8 mode)
 		if (downstream_hpd_needs_d0(intel_dp))
 			return;
 
+		intel_dp_invalidate_source_oui(intel_dp);
+
 		ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, mode);
 	} else {
 		struct intel_lspcon *lspcon = dp_to_lspcon(intel_dp);
@@ -3397,8 +3411,7 @@ 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
@@ -4115,7 +4128,7 @@ 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 3b869429e5756..0449d1d3f175d 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);
 
-- 
2.44.2

[PATCH v2 3/3] drm/i915/dp: Write the source OUI for non-eDP sinks as well

[Imre Deak]

At least the i-tec USB-C Nano 2x Display Docking Station (containing a
Synaptics MST branch device) requires the driver to update the source
OUI DPCD registers to expose its DSC capability. Accordingly update the
OUI for all sink types (besides eDP where this has been done already).

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11776
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 2d6ffbeae07a0..3cc4ef8744f88 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3341,9 +3341,6 @@ intel_dp_init_source_oui(struct intel_dp *intel_dp)
 	u8 oui[] = { 0x00, 0xaa, 0x01 };
 	u8 buf[3] = {};
 
-	if (!intel_dp_is_edp(intel_dp))
-		return;
-
 	/*
 	 * 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
@@ -4159,6 +4156,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 	if (intel_dp_init_lttpr_and_dprx_caps(intel_dp) < 0)
 		return false;
 
+	intel_dp_init_source_oui(intel_dp);
+
 	/*
 	 * Don't clobber cached eDP rates. Also skip re-reading
 	 * the OUI/ID since we know it won't change.
@@ -6035,6 +6034,8 @@ intel_dp_hpd_pulse(struct intel_digital_port *dig_port, bool long_hpd)
 
 	if (long_hpd) {
 		intel_dp->reset_link_params = true;
+		intel_dp_invalidate_source_oui(intel_dp);
+
 		return IRQ_NONE;
 	}
 
-- 
2.44.2

Re: [PATCH v2 2/3] drm/i915/dp: Track source OUI validity explicitly

[Jani Nikula]

On Tue, 01 Oct 2024, Imre Deak <imre.deak@intel.com> 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.
>
> This is required by the next patch updating the source OUI on non-eDP
> sink types as well.
>
> Signed-off-by: Imre Deak <imre.deak@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       | 25 ++++++++++++++-----
>  drivers/gpu/drm/i915/display/intel_dp.h       |  1 +
>  5 files changed, 23 insertions(+), 6 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 7ff97e5b83dd5..ad84ffa31c97f 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1757,6 +1757,7 @@ 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 b7661529f1927..2d6ffbeae07a0 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3335,31 +3335,43 @@ 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;
> +
>  	/*
>  	 * 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 (!intel_dp->oui_valid) {
>  		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;
> +			intel_dp->oui_valid = true;
>  		}
>  	}
>  
> +	if (intel_dp->oui_valid)
> +		return;
> +
>  	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");
>  
>  	intel_dp->last_oui_write = jiffies;
> +	intel_dp->oui_valid = true;

Looking at patches 1 and 2, I'm thinking we don't need two members for
this.

Just make intel_dp->last_oui_write == 0 mean "invalid".

BR,
Jani.


> +}
> +
> +void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp)
> +{
> +	intel_dp->oui_valid = false;
>  }
>  
>  void intel_dp_wait_source_oui(struct intel_dp *intel_dp)
> @@ -3390,6 +3402,8 @@ void intel_dp_set_power(struct intel_dp *intel_dp, u8 mode)
>  		if (downstream_hpd_needs_d0(intel_dp))
>  			return;
>  
> +		intel_dp_invalidate_source_oui(intel_dp);
> +
>  		ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, mode);
>  	} else {
>  		struct intel_lspcon *lspcon = dp_to_lspcon(intel_dp);
> @@ -3397,8 +3411,7 @@ 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
> @@ -4115,7 +4128,7 @@ 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 3b869429e5756..0449d1d3f175d 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);

-- 
Jani Nikula, Intel

Re: [PATCH v2 2/3] drm/i915/dp: Track source OUI validity explicitly

[Imre Deak]

On Tue, Oct 01, 2024 at 04:01:55PM +0300, Jani Nikula wrote:
> On Tue, 01 Oct 2024, Imre Deak <imre.deak@intel.com> 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.
> >
> > This is required by the next patch updating the source OUI on non-eDP
> > sink types as well.
> >
> > Signed-off-by: Imre Deak <imre.deak@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       | 25 ++++++++++++++-----
> >  drivers/gpu/drm/i915/display/intel_dp.h       |  1 +
> >  5 files changed, 23 insertions(+), 6 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 7ff97e5b83dd5..ad84ffa31c97f 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1757,6 +1757,7 @@ 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 b7661529f1927..2d6ffbeae07a0 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -3335,31 +3335,43 @@ 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;
> > +
> >  	/*
> >  	 * 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 (!intel_dp->oui_valid) {
> >  		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;
> > +			intel_dp->oui_valid = true;
> >  		}
> >  	}
> >  
> > +	if (intel_dp->oui_valid)
> > +		return;
> > +
> >  	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");
> >  
> >  	intel_dp->last_oui_write = jiffies;
> > +	intel_dp->oui_valid = true;
> 
> Looking at patches 1 and 2, I'm thinking we don't need two members for
> this.
> 
> Just make intel_dp->last_oui_write == 0 mean "invalid".

0 is a valid jiffies value and then 0 shouldn't be used when setting
last_oui_write. Not sure if that's better.

> 
> BR,
> Jani.
> 
> 
> > +}
> > +
> > +void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp)
> > +{
> > +	intel_dp->oui_valid = false;
> >  }
> >  
> >  void intel_dp_wait_source_oui(struct intel_dp *intel_dp)
> > @@ -3390,6 +3402,8 @@ void intel_dp_set_power(struct intel_dp *intel_dp, u8 mode)
> >  		if (downstream_hpd_needs_d0(intel_dp))
> >  			return;
> >  
> > +		intel_dp_invalidate_source_oui(intel_dp);
> > +
> >  		ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, mode);
> >  	} else {
> >  		struct intel_lspcon *lspcon = dp_to_lspcon(intel_dp);
> > @@ -3397,8 +3411,7 @@ 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
> > @@ -4115,7 +4128,7 @@ 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 3b869429e5756..0449d1d3f175d 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);
> 
> -- 
> Jani Nikula, Intel