[PATCH 18/18] drm/vc4: hdmi: Force YUV422 if the rate is too high

[Thomas Zimmermann]

Am 17.03.21 um 16:43 schrieb Maxime Ripard:
> When using the modes that need the highest pixel rate we support (such
> as 4k at 60Hz), using a 10 or 12 bpc output will put us over the limit
> of what we can achieve.
> 
> In such a case, let's force our output to be YUV422 so that we can go
> back down under the required clock rate.
> 
> Signed-off-by: Maxime Ripard <maxime at cerno.tech>

Acked-by: Thomas Zimmermann <tzimmermann at suse.de>

> ---
>   drivers/gpu/drm/vc4/vc4_hdmi.c | 37 +++++++++++++++++++++++++++++++++-
>   1 file changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> index c4f91d39d91c..12eda1e76338 100644
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@ -1029,6 +1029,41 @@ static unsigned long vc4_hdmi_calc_pixel_rate(struct drm_bridge *bridge,
>   	return pixel_rate;
>   }
>   
> +static u32 *vc4_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
> +						       struct drm_bridge_state *bridge_state,
> +						       struct drm_crtc_state *crtc_state,
> +						       struct drm_connector_state *conn_state,
> +						       unsigned int *num_output_fmts)
> +{
> +	struct vc4_hdmi *vc4_hdmi = bridge_to_vc4_hdmi(bridge);
> +	unsigned long long pixel_rate = vc4_hdmi_calc_pixel_rate(bridge,
> +								 bridge_state,
> +								 crtc_state,
> +								 conn_state);
> +
> +	/*
> +	 * If our pixel rate is too fast, force YUV422 and hope it works
> +	 */
> +	if (pixel_rate > vc4_hdmi->variant->max_pixel_clock) {
> +		u32 *output_fmts;
> +
> +		output_fmts = kzalloc(sizeof(*output_fmts), GFP_KERNEL);
> +		if (!output_fmts)
> +			return NULL;
> +
> +		*output_fmts = MEDIA_BUS_FMT_UYVY8_1X16;
> +		*num_output_fmts = 1;
> +
> +		return output_fmts;
> +	}
> +
> +	return drm_atomic_helper_bridge_hdmi_get_output_bus_fmts(bridge,
> +								 bridge_state,
> +								 crtc_state,
> +								 conn_state,
> +								 num_output_fmts);
> +}
> +
>   static int vc4_hdmi_bridge_atomic_check(struct drm_bridge *bridge,
>   					struct drm_bridge_state *bridge_state,
>   					struct drm_crtc_state *crtc_state,
> @@ -1088,7 +1123,7 @@ static const struct drm_bridge_funcs vc4_hdmi_bridge_funcs = {
>   	.atomic_check =	vc4_hdmi_bridge_atomic_check,
>   	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
>   	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
> -	.atomic_get_output_bus_fmts = drm_atomic_helper_bridge_hdmi_get_output_bus_fmts,
> +	.atomic_get_output_bus_fmts = vc4_hdmi_bridge_atomic_get_output_bus_fmts,
>   	.atomic_reset = drm_atomic_helper_bridge_reset,
>   	.mode_valid =	vc4_hdmi_bridge_mode_valid,
>   };
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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