Re: [PATCH v2] drm/vkms: add module parameter to set background color

["Maíra Canal" <mcanal@igalia.com>]

On 4/11/23 05:58, Simon Ser wrote:
> Hi,
> 
> On Monday, April 10th, 2023 at 19:50, Melissa Wen <mwen@igalia.com> wrote:
> 
>> On 04/10, Simon Ser wrote:
>>
>>> I think this should be a KMS property instead of a module parameter.
>>> Is there a reason why this patch uses a module parameter? It breaks
>>> user-space expectations.
>>
>> a KMS property is what we have on vkms TODO [1] and the module parameter
>> was Maíra's first step to open a discussion for this property [2].
>> AFAIK, we would need to create the KMS property first, but it seems
>> there isn't an userspace case/need to support this API change.
>> Do you know any valid use cases to support a bkg color property?
> 
> There have been previous attempts for msm [1] and i915 [2].
> 
>  From user-space PoV, a KMS property would be useful, for instance to
> render single color background images. I can type some user-space code
> if that helps.

I believe that, if we have some user-space code, we can push this as a
KMS property. If you can provide some user-space code, I can work on
the KMS property to back the use case and we can move this forward.

> 
> If this is a module parameter instead of a KMS property, what purpose
> does this achieve? What is the use-case? Just trying to understand the
> motivation here.
> 

This was a attempt to start the discussion about the background color
property. Without the user-space use case, we cannot move this forward
and as I didn't have a user-space use case, I decided to implement it as
a module parameter.

Best Regards,
- Maíra Canal

> Thanks,
> 
> Simon
> 
> [1]: https://lore.kernel.org/dri-devel/20221028225952.160-1-quic_jesszhan@quicinc.com/
> [2]: https://lore.kernel.org/dri-devel/20190930224707.14904-1-matthew.d.roper@intel.com/