bridge/microchip_lvds panel usage

bridge/microchip_lvds panel usage

[Anusha Srivatsa]

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Hey folks,

Can someone please explain why the driver looks for a panel here:
https://elixir.bootlin.com/linux/v6.14.11/source/drivers/gpu/drm/bridge/microchip-lvds.c#L182
and doesnt use it or set it up anywhere?

I bumped into this while working on converting of_drm_find_panel() callers
and the lvds->panel usage in this driver felt off. Am I missing something?


Thanks,
Anusha

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Re: bridge/microchip_lvds panel usage

[Laurent Pinchart]

On Tue, Jun 17, 2025 at 10:36:34AM -0500, Anusha Srivatsa wrote:
> Hey folks,
> 
> Can someone please explain why the driver looks for a panel here:
> https://elixir.bootlin.com/linux/v6.14.11/source/drivers/gpu/drm/bridge/
> microchip-lvds.c#L182 and doesnt use it or set it up anywhere?
> 
> I bumped into this while working on converting of_drm_find_panel() callers and
> the lvds->panel usage in this driver felt off. Am I missing something?

That doesn't seem needed.

By the way, please use plain text when posting to kernel mailing lists.

-- 
Regards,

Laurent Pinchart

Re: bridge/microchip_lvds panel usage

[Dharma.B]

Hi Laurent & Anusha,

On 18/06/25 5:06 am, Laurent Pinchart wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Tue, Jun 17, 2025 at 10:36:34AM -0500, Anusha Srivatsa wrote:
>> Hey folks,
>>
>> Can someone please explain why the driver looks for a panel here:
>> https://elixir.bootlin.com/linux/v6.14.11/source/drivers/gpu/drm/bridge/
>> microchip-lvds.c#L182 and doesnt use it or set it up anywhere?
>>
>> I bumped into this while working on converting of_drm_find_panel() callers and
>> the lvds->panel usage in this driver felt off. Am I missing something?
> 
> That doesn't seem needed.

Currently the LVDS controller driver is hardcoded to map LVDS lanes to 
the JEIDA format.

In order to support the other format "VESA", we need this to query the 
panel driver and set the appropriate format accordingly.

"drm_panel_get_modes(lvds->panel, connector)"

We'll be submitting the patch upstream shortly.

> 
> By the way, please use plain text when posting to kernel mailing lists.
> 
> --
> Regards,
> 
> Laurent Pinchart


-- 
With Best Regards,
Dharma B.

Re: bridge/microchip_lvds panel usage

[Laurent Pinchart]

On Wed, Jun 18, 2025 at 03:50:11AM +0000, Dharma.B@microchip.com wrote:
> On 18/06/25 5:06 am, Laurent Pinchart wrote:
> > On Tue, Jun 17, 2025 at 10:36:34AM -0500, Anusha Srivatsa wrote:
> >> Hey folks,
> >>
> >> Can someone please explain why the driver looks for a panel here:
> >> https://elixir.bootlin.com/linux/v6.14.11/source/drivers/gpu/drm/bridge/
> >> microchip-lvds.c#L182 and doesnt use it or set it up anywhere?
> >>
> >> I bumped into this while working on converting of_drm_find_panel() callers and
> >> the lvds->panel usage in this driver felt off. Am I missing something?
> > 
> > That doesn't seem needed.
> 
> Currently the LVDS controller driver is hardcoded to map LVDS lanes to 
> the JEIDA format.
> 
> In order to support the other format "VESA", we need this to query the 
> panel driver and set the appropriate format accordingly.
> 
> "drm_panel_get_modes(lvds->panel, connector)"

It would be nice if this could be done using the bridge API instead. An
LVDS sink does not necessarily need to be a panel.

> We'll be submitting the patch upstream shortly.
> 
> > By the way, please use plain text when posting to kernel mailing lists.

-- 
Regards,

Laurent Pinchart

Re: bridge/microchip_lvds panel usage

[Dharma.B]

Hi Laurent,

On 18/06/25 2:25 pm, Laurent Pinchart wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Wed, Jun 18, 2025 at 03:50:11AM +0000, Dharma.B@microchip.com wrote:
>> On 18/06/25 5:06 am, Laurent Pinchart wrote:
>>> On Tue, Jun 17, 2025 at 10:36:34AM -0500, Anusha Srivatsa wrote:
>>>> Hey folks,
>>>>
>>>> Can someone please explain why the driver looks for a panel here:
>>>> https://elixir.bootlin.com/linux/v6.14.11/source/drivers/gpu/drm/bridge/
>>>> microchip-lvds.c#L182 and doesnt use it or set it up anywhere?
>>>>
>>>> I bumped into this while working on converting of_drm_find_panel() callers and
>>>> the lvds->panel usage in this driver felt off. Am I missing something?
>>>
>>> That doesn't seem needed.
>>
>> Currently the LVDS controller driver is hardcoded to map LVDS lanes to
>> the JEIDA format.
>>
>> In order to support the other format "VESA", we need this to query the
>> panel driver and set the appropriate format accordingly.
>>
>> "drm_panel_get_modes(lvds->panel, connector)"
> 
> It would be nice if this could be done using the bridge API instead. An
> LVDS sink does not necessarily need to be a panel.

Here is the updated patch
https://lore.kernel.org/lkml/20250623-microchip-lvds-v2-1-8ecbabc6abc4@microchip.com/

I will send another patch to remove "lvds->panel" as it is unused.

Thanks.
> 
>> We'll be submitting the patch upstream shortly.
>>
>>> By the way, please use plain text when posting to kernel mailing lists.
> 
> --
> Regards,
> 
> Laurent Pinchart


-- 
With Best Regards,
Dharma B.