[PATCH] drm: simple_kms_helper: Add mode_valid() callback support

[thierry.reding@gmail.com (Thierry Reding)]

On Tue, Feb 20, 2018 at 08:28:59AM +0100, Linus Walleij wrote:
> The PL111 needs to filter valid modes based on memory bandwidth.
> I guess it is a pretty simple operation, so we can still claim
> the DRM KMS helper pipeline is simple after adding this (optional)
> vtable callback.
> 
> Reviewed-by: Eric Anholt <eric@anholt.net>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> ChangeLog v1->v2:
> - Fix up the kerneldoc to just refer to the enum.
> - Collect Eric's and Daniel's review tags.
> ---
>  drivers/gpu/drm/drm_simple_kms_helper.c | 15 +++++++++++++++
>  include/drm/drm_simple_kms_helper.h     | 14 ++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
> index 9f3b1c94802b..652cde9a5a6b 100644
> --- a/drivers/gpu/drm/drm_simple_kms_helper.c
> +++ b/drivers/gpu/drm/drm_simple_kms_helper.c
> @@ -34,6 +34,20 @@ static const struct drm_encoder_funcs drm_simple_kms_encoder_funcs = {
>  	.destroy = drm_encoder_cleanup,
>  };
>  
> +static enum drm_mode_status
> +drm_simple_kms_crtc_mode_valid(struct drm_crtc *crtc,
> +			       const struct drm_display_mode *mode)
> +{
> +	struct drm_simple_display_pipe *pipe;
> +
> +	pipe = container_of(crtc, struct drm_simple_display_pipe, crtc);
> +	if (!pipe->funcs || !pipe->funcs->mode_valid)
> +		/* Anything goes */
> +		return MODE_OK;
> +
> +	return pipe->funcs->mode_valid(crtc, mode);
> +}
> +
>  static int drm_simple_kms_crtc_check(struct drm_crtc *crtc,
>  				     struct drm_crtc_state *state)
>  {
> @@ -72,6 +86,7 @@ static void drm_simple_kms_crtc_disable(struct drm_crtc *crtc,
>  }
>  
>  static const struct drm_crtc_helper_funcs drm_simple_kms_crtc_helper_funcs = {
> +	.mode_valid = drm_simple_kms_crtc_mode_valid,
>  	.atomic_check = drm_simple_kms_crtc_check,
>  	.atomic_enable = drm_simple_kms_crtc_enable,
>  	.atomic_disable = drm_simple_kms_crtc_disable,
> diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
> index 6d9adbb46293..d9e4c3c3f009 100644
> --- a/include/drm/drm_simple_kms_helper.h
> +++ b/include/drm/drm_simple_kms_helper.h
> @@ -21,6 +21,20 @@ struct drm_simple_display_pipe;
>   *                                        display pipeline
>   */
>  struct drm_simple_display_pipe_funcs {
> +	/**
> +	 * @mode_valid:
> +	 *
> +	 * This function is called to filter out valid modes from the
> +	 * suggestions suggested by the bridge or display. This optional

This is a little awkward to read. Perhaps something like "... filter out
valid modes from those suggested by..."?

Otherwise looks good:

Reviewed-by: Thierry Reding <treding@nvidia.com>
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