[PATCH v2 0/3] Add DSI Port B input support for LT9611 HDMI bridge

[PATCH v2 0/3] Add DSI Port B input support for LT9611 HDMI bridge

[Hongyang Zhao]

The LT9611 HDMI bridge has two DSI input ports (Port A and Port B).
The current driver only supports Port A or dual-port (A+B) mode, but
some boards like RubikPi3 connect DSI to Port B only.

This series adds support for using DSI Port B as the input source by
utilizing the existing ports mechanism in devicetree:

- port@0 corresponds to LT9611 DSI Port A input
- port@1 corresponds to LT9611 DSI Port B input

The driver detects which ports are populated and configures the hardware
accordingly. When only port@1 is present, it configures port swap
(register 0x8303 bit 6) and byte_clk source (register 0x8250 bit 3:2)
for Port B operation.

Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
---
Changes in v2:
- Use ports mechanism instead of boolean property
- port@0 corresponds to LT9611 Port A, port@1 to Port B
- Driver detects which port is populated and configures accordingly
- Link to v1: https://lore.kernel.org/r/20260127-rubikpi-next-20260116-v1-0-0286c75150c5@thundersoft.com

---
Hongyang Zhao (3):
      dt-bindings: display: lt9611: Support single Port B input
      drm/bridge: lt9611: Add support for single Port B input
      arm64: dts: qcom: qcs6490-rubikpi3: Use lt9611 DSI Port B

 .../bindings/display/bridge/lontium,lt9611.yaml    | 15 +++++--
 .../boot/dts/qcom/qcs6490-thundercomm-rubikpi3.dts |  8 ++--
 drivers/gpu/drm/bridge/lontium-lt9611.c            | 46 +++++++++++++++-------
 3 files changed, 47 insertions(+), 22 deletions(-)
---
base-commit: 46fe65a2c28ecf5df1a7475aba1f08ccf4c0ac1b
change-id: 20260127-rubikpi-next-20260116-99c1dbea50e4

Best regards,
-- 
Hongyang Zhao <hongyang.zhao@thundersoft.com>

[PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Hongyang Zhao]

The LT9611 has two DSI input ports (Port A and Port B). Update the
binding to clearly document the port mapping and allow using Port B
alone when DSI is physically connected to Port B only.

Changes:
- Clarify port@0 corresponds to DSI Port A input
- Clarify port@1 corresponds to DSI Port B input
- Change port requirement from mandatory port@0 to anyOf port@0/port@1,
  allowing either port to be used independently

Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
Reviewed-by: Roger Shimizu <rosh@debian.org>
---
 .../bindings/display/bridge/lontium,lt9611.yaml           | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml
index 655db8cfdc25..429a06057ae8 100644
--- a/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml
+++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml
@@ -44,21 +44,28 @@ properties:
       port@0:
         $ref: /schemas/graph.yaml#/properties/port
         description:
-          Primary MIPI port-1 for MIPI input
+          DSI Port A input. directly drives the display, or works in
+          combination with Port B for higher resolution displays.
 
       port@1:
         $ref: /schemas/graph.yaml#/properties/port
         description:
-          Additional MIPI port-2 for MIPI input, used in combination
-          with primary MIPI port-1 to drive higher resolution displays
+          DSI Port B input. Can be used alone if DSI is physically
+          connected to Port B, or in combination with Port A for higher
+          resolution displays.
 
       port@2:
         $ref: /schemas/graph.yaml#/properties/port
         description:
           HDMI port for HDMI output
 
+    anyOf:
+      - required:
+          - port@0
+      - required:
+          - port@1
+
     required:
-      - port@0
       - port@2
 
 required:

-- 
2.43.0

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Neil Armstrong]

On 1/28/26 12:15, Hongyang Zhao wrote:
> The LT9611 has two DSI input ports (Port A and Port B). Update the
> binding to clearly document the port mapping and allow using Port B
> alone when DSI is physically connected to Port B only.
> 
> Changes:
> - Clarify port@0 corresponds to DSI Port A input
> - Clarify port@1 corresponds to DSI Port B input
> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
>    allowing either port to be used independently
> 
> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> Reviewed-by: Roger Shimizu <rosh@debian.org>
> ---
>   .../bindings/display/bridge/lontium,lt9611.yaml           | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml b/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml
> index 655db8cfdc25..429a06057ae8 100644
> --- a/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml
> @@ -44,21 +44,28 @@ properties:
>         port@0:
>           $ref: /schemas/graph.yaml#/properties/port
>           description:
> -          Primary MIPI port-1 for MIPI input
> +          DSI Port A input. directly drives the display, or works in
> +          combination with Port B for higher resolution displays.
>   
>         port@1:
>           $ref: /schemas/graph.yaml#/properties/port
>           description:
> -          Additional MIPI port-2 for MIPI input, used in combination
> -          with primary MIPI port-1 to drive higher resolution displays
> +          DSI Port B input. Can be used alone if DSI is physically
> +          connected to Port B, or in combination with Port A for higher
> +          resolution displays.
>   
>         port@2:
>           $ref: /schemas/graph.yaml#/properties/port
>           description:
>             HDMI port for HDMI output
>   
> +    anyOf:
> +      - required:
> +          - port@0
> +      - required:
> +          - port@1
> +
>       required:
> -      - port@0
>         - port@2
>   
>   required:
> 

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Thanks,
Neil

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Krzysztof Kozlowski]

On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
> The LT9611 has two DSI input ports (Port A and Port B). Update the
> binding to clearly document the port mapping and allow using Port B
> alone when DSI is physically connected to Port B only.
> 
> Changes:
> - Clarify port@0 corresponds to DSI Port A input
> - Clarify port@1 corresponds to DSI Port B input
> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
>   allowing either port to be used independently
> 
> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> Reviewed-by: Roger Shimizu <rosh@debian.org>

Where did this review happen? V1 had this tag, but the patch was
completely different, which means you were supposed to drop the tag.
Please perform review in public.


Best regards,
Krzysztof

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Roger Shimizu]

On Thu, Feb 5, 2026 at 5:07 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
> > The LT9611 has two DSI input ports (Port A and Port B). Update the
> > binding to clearly document the port mapping and allow using Port B
> > alone when DSI is physically connected to Port B only.
> >
> > Changes:
> > - Clarify port@0 corresponds to DSI Port A input
> > - Clarify port@1 corresponds to DSI Port B input
> > - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
> >   allowing either port to be used independently
> >
> > Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> > Reviewed-by: Roger Shimizu <rosh@debian.org>
>
> Where did this review happen? V1 had this tag, but the patch was
> completely different, which means you were supposed to drop the tag.
> Please perform review in public.

FYI. v2 was updated per review feedback, which is public:
https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/

Maybe it's better to add this info to v2 cover letter / trailer for
easier reading.

-Roger

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Krzysztof Kozlowski]

On 05/02/2026 21:31, Roger Shimizu wrote:
> On Thu, Feb 5, 2026 at 5:07 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
>>> The LT9611 has two DSI input ports (Port A and Port B). Update the
>>> binding to clearly document the port mapping and allow using Port B
>>> alone when DSI is physically connected to Port B only.
>>>
>>> Changes:
>>> - Clarify port@0 corresponds to DSI Port A input
>>> - Clarify port@1 corresponds to DSI Port B input
>>> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
>>>   allowing either port to be used independently
>>>
>>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
>>> Reviewed-by: Roger Shimizu <rosh@debian.org>
>>
>> Where did this review happen? V1 had this tag, but the patch was
>> completely different, which means you were supposed to drop the tag.
>> Please perform review in public.
> 
> FYI. v2 was updated per review feedback, which is public:
> https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/

Link above is not from Roger, so again - where did the review leading to
above tag happen?

Best regards,
Krzysztof

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Roger Shimizu]

On Thu, Feb 5, 2026 at 11:08 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 05/02/2026 21:31, Roger Shimizu wrote:
> > On Thu, Feb 5, 2026 at 5:07 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>
> >> On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
> >>> The LT9611 has two DSI input ports (Port A and Port B). Update the
> >>> binding to clearly document the port mapping and allow using Port B
> >>> alone when DSI is physically connected to Port B only.
> >>>
> >>> Changes:
> >>> - Clarify port@0 corresponds to DSI Port A input
> >>> - Clarify port@1 corresponds to DSI Port B input
> >>> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
> >>>   allowing either port to be used independently
> >>>
> >>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> >>> Reviewed-by: Roger Shimizu <rosh@debian.org>
> >>
> >> Where did this review happen? V1 had this tag, but the patch was
> >> completely different, which means you were supposed to drop the tag.
> >> Please perform review in public.
> >
> > FYI. v2 was updated per review feedback, which is public:
> > https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/
>
> Link above is not from Roger, so again - where did the review leading to
> above tag happen?

Per feedback of v1, v2 was quite different than v1.
For v2, it's close to initial review, because it looks like a new patch.
Of course, if you don't like this way, we can drop this next time.

-Roger

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Krzysztof Kozlowski]

On 06/02/2026 10:49, Roger Shimizu wrote:
> On Thu, Feb 5, 2026 at 11:08 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On 05/02/2026 21:31, Roger Shimizu wrote:
>>> On Thu, Feb 5, 2026 at 5:07 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>>
>>>> On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
>>>>> The LT9611 has two DSI input ports (Port A and Port B). Update the
>>>>> binding to clearly document the port mapping and allow using Port B
>>>>> alone when DSI is physically connected to Port B only.
>>>>>
>>>>> Changes:
>>>>> - Clarify port@0 corresponds to DSI Port A input
>>>>> - Clarify port@1 corresponds to DSI Port B input
>>>>> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
>>>>>   allowing either port to be used independently
>>>>>
>>>>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
>>>>> Reviewed-by: Roger Shimizu <rosh@debian.org>
>>>>
>>>> Where did this review happen? V1 had this tag, but the patch was
>>>> completely different, which means you were supposed to drop the tag.
>>>> Please perform review in public.
>>>
>>> FYI. v2 was updated per review feedback, which is public:
>>> https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/
>>
>> Link above is not from Roger, so again - where did the review leading to
>> above tag happen?
> 
> Per feedback of v1, v2 was quite different than v1.
> For v2, it's close to initial review, because it looks like a new patch.

Where was the review of v2 given?

The patch is entirely different. I already said it. I also said what is
expected in such case. It is also documented:

https://elixir.bootlin.com/linux/v6.12-rc3/source/Documentation/process/submitting-patches.rst#L577



Best regards,
Krzysztof

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Roger Shimizu]

On Fri, Feb 6, 2026 at 2:56 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 06/02/2026 10:49, Roger Shimizu wrote:
> > On Thu, Feb 5, 2026 at 11:08 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>
> >> On 05/02/2026 21:31, Roger Shimizu wrote:
> >>> On Thu, Feb 5, 2026 at 5:07 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>>>
> >>>> On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
> >>>>> The LT9611 has two DSI input ports (Port A and Port B). Update the
> >>>>> binding to clearly document the port mapping and allow using Port B
> >>>>> alone when DSI is physically connected to Port B only.
> >>>>>
> >>>>> Changes:
> >>>>> - Clarify port@0 corresponds to DSI Port A input
> >>>>> - Clarify port@1 corresponds to DSI Port B input
> >>>>> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
> >>>>>   allowing either port to be used independently
> >>>>>
> >>>>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> >>>>> Reviewed-by: Roger Shimizu <rosh@debian.org>
> >>>>
> >>>> Where did this review happen? V1 had this tag, but the patch was
> >>>> completely different, which means you were supposed to drop the tag.
> >>>> Please perform review in public.
> >>>
> >>> FYI. v2 was updated per review feedback, which is public:
> >>> https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/
> >>
> >> Link above is not from Roger, so again - where did the review leading to
> >> above tag happen?
> >
> > Per feedback of v1, v2 was quite different than v1.
> > For v2, it's close to initial review, because it looks like a new patch.
>
> Where was the review of v2 given?
>
> The patch is entirely different. I already said it. I also said what is
> expected in such case. It is also documented:
>
> https://elixir.bootlin.com/linux/v6.12-rc3/source/Documentation/process/submitting-patches.rst#L577

Thanks for the guide!
Yes, v2 was reviewed in private. I'll inform Hongyang to remove the
tag when he sends the next series.

-Roger

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Krzysztof Kozlowski]

On 07/02/2026 06:22, Roger Shimizu wrote:
> On Fri, Feb 6, 2026 at 2:56 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On 06/02/2026 10:49, Roger Shimizu wrote:
>>> On Thu, Feb 5, 2026 at 11:08 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>>
>>>> On 05/02/2026 21:31, Roger Shimizu wrote:
>>>>> On Thu, Feb 5, 2026 at 5:07 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>>>>
>>>>>> On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
>>>>>>> The LT9611 has two DSI input ports (Port A and Port B). Update the
>>>>>>> binding to clearly document the port mapping and allow using Port B
>>>>>>> alone when DSI is physically connected to Port B only.
>>>>>>>
>>>>>>> Changes:
>>>>>>> - Clarify port@0 corresponds to DSI Port A input
>>>>>>> - Clarify port@1 corresponds to DSI Port B input
>>>>>>> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
>>>>>>>   allowing either port to be used independently
>>>>>>>
>>>>>>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
>>>>>>> Reviewed-by: Roger Shimizu <rosh@debian.org>
>>>>>>
>>>>>> Where did this review happen? V1 had this tag, but the patch was
>>>>>> completely different, which means you were supposed to drop the tag.
>>>>>> Please perform review in public.
>>>>>
>>>>> FYI. v2 was updated per review feedback, which is public:
>>>>> https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/
>>>>
>>>> Link above is not from Roger, so again - where did the review leading to
>>>> above tag happen?
>>>
>>> Per feedback of v1, v2 was quite different than v1.
>>> For v2, it's close to initial review, because it looks like a new patch.
>>
>> Where was the review of v2 given?
>>
>> The patch is entirely different. I already said it. I also said what is
>> expected in such case. It is also documented:
>>
>> https://elixir.bootlin.com/linux/v6.12-rc3/source/Documentation/process/submitting-patches.rst#L577
> 
> Thanks for the guide!
> Yes, v2 was reviewed in private. I'll inform Hongyang to remove the
> tag when he sends the next series.

I am repeating myself but only because you really avoid answering.

I understand v1 was reviewed in private, before posting, but why are you
developing in private also v2? After v1 was posted, this should be all
done in public.

I have no trust in private reviews happening between versions.
Especially if v1 is send on 27th Jan and next day v2 is sent supposedly
reviewed in private. Really?



Best regards,
Krzysztof

Re: [PATCH v2 1/3] dt-bindings: display: lt9611: Support single Port B input

[Roger Shimizu]

On Sat, Feb 7, 2026 at 1:35 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 07/02/2026 06:22, Roger Shimizu wrote:
> > On Fri, Feb 6, 2026 at 2:56 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>
> >> On 06/02/2026 10:49, Roger Shimizu wrote:
> >>> On Thu, Feb 5, 2026 at 11:08 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>>>
> >>>> On 05/02/2026 21:31, Roger Shimizu wrote:
> >>>>> On Thu, Feb 5, 2026 at 5:07 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>>>>>
> >>>>>> On Wed, Jan 28, 2026 at 07:15:45PM +0800, Hongyang Zhao wrote:
> >>>>>>> The LT9611 has two DSI input ports (Port A and Port B). Update the
> >>>>>>> binding to clearly document the port mapping and allow using Port B
> >>>>>>> alone when DSI is physically connected to Port B only.
> >>>>>>>
> >>>>>>> Changes:
> >>>>>>> - Clarify port@0 corresponds to DSI Port A input
> >>>>>>> - Clarify port@1 corresponds to DSI Port B input
> >>>>>>> - Change port requirement from mandatory port@0 to anyOf port@0/port@1,
> >>>>>>>   allowing either port to be used independently
> >>>>>>>
> >>>>>>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> >>>>>>> Reviewed-by: Roger Shimizu <rosh@debian.org>
> >>>>>>
> >>>>>> Where did this review happen? V1 had this tag, but the patch was
> >>>>>> completely different, which means you were supposed to drop the tag.
> >>>>>> Please perform review in public.
> >>>>>
> >>>>> FYI. v2 was updated per review feedback, which is public:
> >>>>> https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/
> >>>>
> >>>> Link above is not from Roger, so again - where did the review leading to
> >>>> above tag happen?
> >>>
> >>> Per feedback of v1, v2 was quite different than v1.
> >>> For v2, it's close to initial review, because it looks like a new patch.
> >>
> >> Where was the review of v2 given?
> >>
> >> The patch is entirely different. I already said it. I also said what is
> >> expected in such case. It is also documented:
> >>
> >> https://elixir.bootlin.com/linux/v6.12-rc3/source/Documentation/process/submitting-patches.rst#L577
> >
> > Thanks for the guide!
> > Yes, v2 was reviewed in private. I'll inform Hongyang to remove the
> > tag when he sends the next series.
>
> I am repeating myself but only because you really avoid answering.

Because I just didn't have the time to check when exactly it happened.
I agree with you that if it's public, then it's easier to check the
mailing list.

> I understand v1 was reviewed in private, before posting, but why are you
> developing in private also v2? After v1 was posted, this should be all
> done in public.

Hongyang wrote the patch. Credit to him.
I just helped to check.
v2 was a rewrite since feedback of v1, so we think it's like new
patch, which was reviewed in private.

> I have no trust in private reviews happening between versions.
> Especially if v1 is send on 27th Jan and next day v2 is sent supposedly
> reviewed in private. Really?

This patch is not huge amount of work, in spite of rewriting from v1.
I understand that it's not good to resend a series too quickly, but
for this specific case, the feedback was very convincing, so v2 was
sent out without much waiting.
If you insist on some more waiting period, we can follow it next time.

-Roger

[PATCH v2 2/3] drm/bridge: lt9611: Add support for single Port B input

[Hongyang Zhao]

The LT9611 has two DSI input ports. The driver currently assumes Port A
is always used for single-port configurations. However, some boards
connect DSI to Port B only.

Update the driver to detect which ports are populated from devicetree
and configure the hardware accordingly:

- If only port@1 (Port B) is populated, configure port swap (0x8303
  bit 6) and byte_clk source (0x8250 bit 3:2) for Port B operation
- If both ports are populated, use dual-port mode (Port A + B)
- If only port@0 (Port A) is populated, use single Port A (existing
  behavior)

Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
Reviewed-by: Roger Shimizu <rosh@debian.org>
---
 drivers/gpu/drm/bridge/lontium-lt9611.c | 46 +++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/bridge/lontium-lt9611.c b/drivers/gpu/drm/bridge/lontium-lt9611.c
index a2d032ee4744..5fc22489b078 100644
--- a/drivers/gpu/drm/bridge/lontium-lt9611.c
+++ b/drivers/gpu/drm/bridge/lontium-lt9611.c
@@ -116,12 +116,25 @@ static int lt9611_mipi_input_digital(struct lt9611 *lt9611,
 		{ 0x830a, 0x00 },
 		{ 0x824f, 0x80 },
 		{ 0x8250, 0x10 },
+		{ 0x8303, 0x00 },
 		{ 0x8302, 0x0a },
 		{ 0x8306, 0x0a },
 	};
 
-	if (lt9611->dsi1_node)
-		reg_cfg[1].def = 0x03;
+	if (lt9611->dsi1_node) {
+		if (lt9611->dsi0_node) {
+			/* Dual port (Port A + B) */
+			reg_cfg[1].def = 0x03;
+		} else {
+			/*
+			 * Single port B:
+			 * - 0x8303 bit 6: port swap (1=PortB as primary)
+			 * - 0x8250 bit 3:2: byte_clk source (01=PortB)
+			 */
+			reg_cfg[3].def = 0x14;
+			reg_cfg[4].def = 0x40;
+		}
+	}
 
 	return regmap_multi_reg_write(lt9611->regmap, reg_cfg, ARRAY_SIZE(reg_cfg));
 }
@@ -202,7 +215,9 @@ static void lt9611_pcr_setup(struct lt9611 *lt9611, const struct drm_display_mod
 	regmap_write(lt9611->regmap, 0x831d, pol);
 
 	regmap_multi_reg_write(lt9611->regmap, reg_cfg, ARRAY_SIZE(reg_cfg));
-	if (lt9611->dsi1_node) {
+
+	/* dual port: configure hact for combining two DSI inputs */
+	if (lt9611->dsi0_node && lt9611->dsi1_node) {
 		unsigned int hact = mode->hdisplay;
 
 		hact >>= 2;
@@ -759,7 +774,8 @@ static enum drm_mode_status lt9611_bridge_mode_valid(struct drm_bridge *bridge,
 	if (mode->hdisplay > 3840)
 		return MODE_BAD_HVALUE;
 
-	if (mode->hdisplay > 2000 && !lt9611->dsi1_node)
+	/* high resolution requires dual port (Port A + B) */
+	if (mode->hdisplay > 2000 && !(lt9611->dsi0_node && lt9611->dsi1_node))
 		return MODE_PANEL;
 
 	return MODE_OK;
@@ -1015,13 +1031,13 @@ static int lt9611_parse_dt(struct device *dev,
 			   struct lt9611 *lt9611)
 {
 	lt9611->dsi0_node = of_graph_get_remote_node(dev->of_node, 0, -1);
-	if (!lt9611->dsi0_node) {
-		dev_err(lt9611->dev, "failed to get remote node for primary dsi\n");
+	lt9611->dsi1_node = of_graph_get_remote_node(dev->of_node, 1, -1);
+
+	if (!lt9611->dsi0_node && !lt9611->dsi1_node) {
+		dev_err(lt9611->dev, "failed to get remote node for dsi\n");
 		return -ENODEV;
 	}
 
-	lt9611->dsi1_node = of_graph_get_remote_node(dev->of_node, 1, -1);
-
 	lt9611->ac_mode = of_property_read_bool(dev->of_node, "lt,ac-mode");
 
 	return drm_of_find_panel_or_bridge(dev->of_node, 2, -1, NULL, &lt9611->next_bridge);
@@ -1142,14 +1158,16 @@ static int lt9611_probe(struct i2c_client *client)
 
 	drm_bridge_add(&lt9611->bridge);
 
-	/* Attach primary DSI */
-	lt9611->dsi0 = lt9611_attach_dsi(lt9611, lt9611->dsi0_node);
-	if (IS_ERR(lt9611->dsi0)) {
-		ret = PTR_ERR(lt9611->dsi0);
-		goto err_remove_bridge;
+	/* Attach primary DSI (directly drives or Port A in dual-port mode) */
+	if (lt9611->dsi0_node) {
+		lt9611->dsi0 = lt9611_attach_dsi(lt9611, lt9611->dsi0_node);
+		if (IS_ERR(lt9611->dsi0)) {
+			ret = PTR_ERR(lt9611->dsi0);
+			goto err_remove_bridge;
+		}
 	}
 
-	/* Attach secondary DSI, if specified */
+	/* Attach secondary DSI (Port B in single or dual-port mode) */
 	if (lt9611->dsi1_node) {
 		lt9611->dsi1 = lt9611_attach_dsi(lt9611, lt9611->dsi1_node);
 		if (IS_ERR(lt9611->dsi1)) {

-- 
2.43.0

Re: [PATCH v2 2/3] drm/bridge: lt9611: Add support for single Port B input

[Dmitry Baryshkov]

On Wed, Jan 28, 2026 at 07:15:46PM +0800, Hongyang Zhao wrote:
> The LT9611 has two DSI input ports. The driver currently assumes Port A
> is always used for single-port configurations. However, some boards
> connect DSI to Port B only.
> 
> Update the driver to detect which ports are populated from devicetree
> and configure the hardware accordingly:
> 
> - If only port@1 (Port B) is populated, configure port swap (0x8303
>   bit 6) and byte_clk source (0x8250 bit 3:2) for Port B operation
> - If both ports are populated, use dual-port mode (Port A + B)
> - If only port@0 (Port A) is populated, use single Port A (existing
>   behavior)
> 
> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> Reviewed-by: Roger Shimizu <rosh@debian.org>
> ---
>  drivers/gpu/drm/bridge/lontium-lt9611.c | 46 +++++++++++++++++++++++----------
>  1 file changed, 32 insertions(+), 14 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

[PATCH v2 3/3] arm64: dts: qcom: qcs6490-rubikpi3: Use lt9611 DSI Port B

[Hongyang Zhao]

The LT9611 HDMI bridge on RubikPi3 has DSI physically connected to
Port B. Update the devicetree to use port@1 which corresponds to
Port B input on the LT9611.

Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
Reviewed-by: Roger Shimizu <rosh@debian.org>
---
 arch/arm64/boot/dts/qcom/qcs6490-thundercomm-rubikpi3.dts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/qcs6490-thundercomm-rubikpi3.dts b/arch/arm64/boot/dts/qcom/qcs6490-thundercomm-rubikpi3.dts
index 0b64a0b91202..f47efca42d48 100644
--- a/arch/arm64/boot/dts/qcom/qcs6490-thundercomm-rubikpi3.dts
+++ b/arch/arm64/boot/dts/qcom/qcs6490-thundercomm-rubikpi3.dts
@@ -755,10 +755,10 @@ ports {
 			#address-cells = <1>;
 			#size-cells = <0>;
 
-			port@0 {
-				reg = <0>;
+			port@1 {
+				reg = <1>;
 
-				lt9611_a: endpoint {
+				lt9611_b: endpoint {
 					remote-endpoint = <&mdss_dsi0_out>;
 				};
 			};
@@ -801,7 +801,7 @@ &mdss_dsi {
 };
 
 &mdss_dsi0_out {
-	remote-endpoint = <&lt9611_a>;
+	remote-endpoint = <&lt9611_b>;
 	data-lanes = <0 1 2 3>;
 };
 

-- 
2.43.0

Re: [PATCH v2 3/3] arm64: dts: qcom: qcs6490-rubikpi3: Use lt9611 DSI Port B

[Konrad Dybcio]

On 1/28/26 12:15 PM, Hongyang Zhao wrote:
> The LT9611 HDMI bridge on RubikPi3 has DSI physically connected to
> Port B. Update the devicetree to use port@1 which corresponds to
> Port B input on the LT9611.
> 
> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> Reviewed-by: Roger Shimizu <rosh@debian.org>
> ---

Fixes: f055a39f6874 ("arm64: dts: qcom: Add qcs6490-rubikpi3 board dts")

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

Re: [PATCH v2 3/3] arm64: dts: qcom: qcs6490-rubikpi3: Use lt9611 DSI Port B

[Krzysztof Kozlowski]

On Wed, Jan 28, 2026 at 07:15:47PM +0800, Hongyang Zhao wrote:
> The LT9611 HDMI bridge on RubikPi3 has DSI physically connected to
> Port B. Update the devicetree to use port@1 which corresponds to
> Port B input on the LT9611.
> 
> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> Reviewed-by: Roger Shimizu <rosh@debian.org>

Where did this happen?

https://lore.kernel.org/all/?q=f%3Arosh%40debian.org

And again, v1 was completely different so how pre-v1-internal-review
could be applied to this v2?

Honestly, initial guidance is useful but continuous development behind
the closed doors is not.

Best regards,
Krzysztof

Re: [PATCH v2 3/3] arm64: dts: qcom: qcs6490-rubikpi3: Use lt9611 DSI Port B

[Roger Shimizu]

On Thu, Feb 5, 2026 at 5:09 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On Wed, Jan 28, 2026 at 07:15:47PM +0800, Hongyang Zhao wrote:
> > The LT9611 HDMI bridge on RubikPi3 has DSI physically connected to
> > Port B. Update the devicetree to use port@1 which corresponds to
> > Port B input on the LT9611.
> >
> > Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> > Reviewed-by: Roger Shimizu <rosh@debian.org>
>
> Where did this happen?
>
> https://lore.kernel.org/all/?q=f%3Arosh%40debian.org
>
> And again, v1 was completely different so how pre-v1-internal-review
> could be applied to this v2?
>
> Honestly, initial guidance is useful but continuous development behind
> the closed doors is not.

FYI. v2 was updated per review feedback, which is public:
https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/

-Roger

Re: [PATCH v2 3/3] arm64: dts: qcom: qcs6490-rubikpi3: Use lt9611 DSI Port B

[Krzysztof Kozlowski]

On 05/02/2026 20:36, Roger Shimizu wrote:
> On Thu, Feb 5, 2026 at 5:09 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>
>> On Wed, Jan 28, 2026 at 07:15:47PM +0800, Hongyang Zhao wrote:
>>> The LT9611 HDMI bridge on RubikPi3 has DSI physically connected to
>>> Port B. Update the devicetree to use port@1 which corresponds to
>>> Port B input on the LT9611.
>>>
>>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
>>> Reviewed-by: Roger Shimizu <rosh@debian.org>
>>
>> Where did this happen?
>>
>> https://lore.kernel.org/all/?q=f%3Arosh%40debian.org
>>
>> And again, v1 was completely different so how pre-v1-internal-review
>> could be applied to this v2?
>>
>> Honestly, initial guidance is useful but continuous development behind
>> the closed doors is not.
> 
> FYI. v2 was updated per review feedback, which is public:
> https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/

What? I asked about the tag. Do you understand how kernel review process
works?

Best regards,
Krzysztof

Re: [PATCH v2 3/3] arm64: dts: qcom: qcs6490-rubikpi3: Use lt9611 DSI Port B

[Roger Shimizu]

On Thu, Feb 5, 2026 at 11:08 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> On 05/02/2026 20:36, Roger Shimizu wrote:
> > On Thu, Feb 5, 2026 at 5:09 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> >>
> >> On Wed, Jan 28, 2026 at 07:15:47PM +0800, Hongyang Zhao wrote:
> >>> The LT9611 HDMI bridge on RubikPi3 has DSI physically connected to
> >>> Port B. Update the devicetree to use port@1 which corresponds to
> >>> Port B input on the LT9611.
> >>>
> >>> Signed-off-by: Hongyang Zhao <hongyang.zhao@thundersoft.com>
> >>> Reviewed-by: Roger Shimizu <rosh@debian.org>
> >>
> >> Where did this happen?
> >>
> >> https://lore.kernel.org/all/?q=f%3Arosh%40debian.org
> >>
> >> And again, v1 was completely different so how pre-v1-internal-review
> >> could be applied to this v2?
> >>
> >> Honestly, initial guidance is useful but continuous development behind
> >> the closed doors is not.
> >
> > FYI. v2 was updated per review feedback, which is public:
> > https://lore.kernel.org/all/7d9041a3-9d2b-469a-9fa7-89d53bbd2a1f@linaro.org/
>
> What? I asked about the tag. Do you understand how kernel review process
> works?

Yes, v2 was reviewed in private.
I'll inform Hongyang to remove the tag when he sends the next series.

-Roger