| Message ID | 20240625120552.145389-1-marex@denx.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/2] dt-bindings: display: bridge: tc358867: Document default DP preemphasis | expand |
Hi Marek, Am Dienstag, 25. Juni 2024, 14:05:14 CEST schrieb Marek Vasut: > Document default DP port preemphasis configurable via new DT property > "toshiba,pre-emphasis". This is useful in case the DP link properties > are known and starting link training from preemphasis setting of 0 dB > is not useful. The preemphasis can be set separately for both DP lanes > in range 0=0dB, 1=3.5dB, 2=6dB . > > This is an endpoint property, not a port property, because the TC9595 > datasheet does mention that the DP might operate in some sort of split > mode, where each DP lane is used to feed one display, so in that case > there might be two endpoints. > > Signed-off-by: Marek Vasut <marex@denx.de> > --- > Cc: Andrzej Hajda <andrzej.hajda@intel.com> > Cc: Conor Dooley <conor+dt@kernel.org> > Cc: Daniel Vetter <daniel@ffwll.ch> > Cc: David Airlie <airlied@gmail.com> > Cc: Jernej Skrabec <jernej.skrabec@gmail.com> > Cc: Jonas Karlman <jonas@kwiboo.se> > Cc: Krzysztof Kozlowski <krzk+dt@kernel.org> > Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com> > Cc: Lucas Stach <l.stach@pengutronix.de> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> > Cc: Maxime Ripard <mripard@kernel.org> > Cc: Neil Armstrong <neil.armstrong@linaro.org> > Cc: Rob Herring <robh@kernel.org> > Cc: Robert Foss <rfoss@kernel.org> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: devicetree@vger.kernel.org > Cc: dri-devel@lists.freedesktop.org > Cc: kernel@dh-electronics.com > --- > V2: - Fix the type to u8 array > - Fix the enum items to match what they represent > V3: - Update commit message, expand on this being an endpoint property > --- > .../display/bridge/toshiba,tc358767.yaml | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml > index 2ad0cd6dd49e0..9490854c22f3b 100644 > --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml > +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml > @@ -98,6 +98,24 @@ properties: > reference to a valid eDP panel input endpoint node. This port is > optional, treated as DP panel if not defined > > + properties: > + endpoint: > + $ref: /schemas/media/video-interfaces.yaml# > + unevaluatedProperties: false > + > + properties: > + toshiba,pre-emphasis: > + description: > + Display port output Pre-Emphasis settings for both DP lanes. > + $ref: /schemas/types.yaml#/definitions/uint8-array > + minItems: 2 > + maxItems: 2 > + items: > + enum: > + - 0 # No pre-emphasis > + - 1 # 3.5dB pre-emphasis > + - 2 # 6dB pre-emphasis > + > oneOf: > - required: > - port@0 > I get this warning: > mx8mp-tqma8mpql-mba8mpxl.dtb: bridge@f: ports:port@2:endpoint: Unevaluated > properties are not allowed ('toshiba,pre-emphasis' was unexpected) DT node looks like this: port@2 { reg = <2>; endpoint { toshiba,pre-emphasis = /bits/ 8 <1 1>; }; }; I think you are missing this change as well: -- 8< -- --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml @@ -92,7 +92,8 @@ properties: reference to a valid DPI output or input endpoint node. port@2: - $ref: /schemas/graph.yaml#/properties/port + $ref: /schemas/graph.yaml#/$defs/port-base + unevaluatedProperties: false description: | eDP/DP output port. The remote endpoint phandle should be a reference to a valid eDP panel input endpoint node. This port is -- 8< -- How would you determine the values to be set here? I suspect it's the value from register DP0_SnkLTChReq (0x6d4) after link training. Are they dependent on the actual display to be attached? Best regards, Alexander
On 6/26/24 9:29 AM, Alexander Stein wrote: Hi, >> + >> oneOf: >> - required: >> - port@0 >> > > I get this warning: >> mx8mp-tqma8mpql-mba8mpxl.dtb: bridge@f: ports:port@2:endpoint: Unevaluated >> properties are not allowed ('toshiba,pre-emphasis' was unexpected) > > DT node looks like this: > > port@2 { > reg = <2>; > > endpoint { > toshiba,pre-emphasis = /bits/ 8 <1 1>; > }; > }; > > I think you are missing this change as well: > -- 8< -- > --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml > +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml > @@ -92,7 +92,8 @@ properties: > reference to a valid DPI output or input endpoint node. > > port@2: > - $ref: /schemas/graph.yaml#/properties/port > + $ref: /schemas/graph.yaml#/$defs/port-base > + unevaluatedProperties: false > description: | > eDP/DP output port. The remote endpoint phandle should be a > reference to a valid eDP panel input endpoint node. This port is > -- 8< -- Picked for V4, thank you ! > How would you determine the values to be set here? I suspect it's the value > from register DP0_SnkLTChReq (0x6d4) after link training. Are they dependent > on the actual display to be attached? In my case, I only did trial-and-error, because the test hardware I have available right now ... well, it is a test hardware and won't work reliably with pre-emphasis 0, so I had to up it a bit.
diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml index 2ad0cd6dd49e0..9490854c22f3b 100644 --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.yaml @@ -98,6 +98,24 @@ properties: reference to a valid eDP panel input endpoint node. This port is optional, treated as DP panel if not defined + properties: + endpoint: + $ref: /schemas/media/video-interfaces.yaml# + unevaluatedProperties: false + + properties: + toshiba,pre-emphasis: + description: + Display port output Pre-Emphasis settings for both DP lanes. + $ref: /schemas/types.yaml#/definitions/uint8-array + minItems: 2 + maxItems: 2 + items: + enum: + - 0 # No pre-emphasis + - 1 # 3.5dB pre-emphasis + - 2 # 6dB pre-emphasis + oneOf: - required: - port@0
Document default DP port preemphasis configurable via new DT property "toshiba,pre-emphasis". This is useful in case the DP link properties are known and starting link training from preemphasis setting of 0 dB is not useful. The preemphasis can be set separately for both DP lanes in range 0=0dB, 1=3.5dB, 2=6dB . This is an endpoint property, not a port property, because the TC9595 datasheet does mention that the DP might operate in some sort of split mode, where each DP lane is used to feed one display, so in that case there might be two endpoints. Signed-off-by: Marek Vasut <marex@denx.de> --- Cc: Andrzej Hajda <andrzej.hajda@intel.com> Cc: Conor Dooley <conor+dt@kernel.org> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: David Airlie <airlied@gmail.com> Cc: Jernej Skrabec <jernej.skrabec@gmail.com> Cc: Jonas Karlman <jonas@kwiboo.se> Cc: Krzysztof Kozlowski <krzk+dt@kernel.org> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com> Cc: Lucas Stach <l.stach@pengutronix.de> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Neil Armstrong <neil.armstrong@linaro.org> Cc: Rob Herring <robh@kernel.org> Cc: Robert Foss <rfoss@kernel.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: devicetree@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: kernel@dh-electronics.com --- V2: - Fix the type to u8 array - Fix the enum items to match what they represent V3: - Update commit message, expand on this being an endpoint property --- .../display/bridge/toshiba,tc358767.yaml | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)