Re: [PATCH 7/7] drm/gud: Add module parameter to control emulation: xrgb8888

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Aug 17, 2021 at 02:29:17PM +0200, Noralf Trønnes wrote:
> For devices that don't support XRGB8888 give the user the ability to
> choose what's most important: Color depth or frames per second.
> 
> Add an 'xrgb8888' module parameter to override the emulation format.
> 
> Assume the user wants full control if xrgb8888 is set and don't set
> DRM_CAP_DUMB_PREFERRED_DEPTH if RGB565 is supported (AFAIK only X.org
> supports this).
> 
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
>  drivers/gpu/drm/gud/gud_drv.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/gud/gud_drv.c b/drivers/gpu/drm/gud/gud_drv.c
> index 3f9d4b9a1e3d..60d27ee5ddbd 100644
> --- a/drivers/gpu/drm/gud/gud_drv.c
> +++ b/drivers/gpu/drm/gud/gud_drv.c
> @@ -30,6 +30,10 @@
>  
>  #include "gud_internal.h"
>  
> +static int gud_xrgb8888;
> +module_param_named(xrgb8888, gud_xrgb8888, int, 0644);
> +MODULE_PARM_DESC(xrgb8888, "XRGB8888 emulation format: GUD_PIXEL_FORMAT_* value, 0=auto, -1=disable [default=auto]");
> +
>  /* Only used internally */
>  static const struct drm_format_info gud_drm_format_r1 = {
>  	.format = GUD_DRM_FORMAT_R1,
> @@ -530,12 +534,12 @@ static int gud_probe(struct usb_interface *intf, const struct usb_device_id *id)
>  		case DRM_FORMAT_RGB332:
>  			fallthrough;
>  		case DRM_FORMAT_RGB888:
> -			if (!xrgb8888_emulation_format)
> +			if (!gud_xrgb8888 && !xrgb8888_emulation_format)
>  				xrgb8888_emulation_format = info;

Shouldn't the emulation format be per drm_device instance?
-Daniel

>  			break;
>  		case DRM_FORMAT_RGB565:
>  			rgb565_supported = true;
> -			if (!xrgb8888_emulation_format)
> +			if (!gud_xrgb8888 && !xrgb8888_emulation_format)
>  				xrgb8888_emulation_format = info;
>  			break;
>  		case DRM_FORMAT_XRGB8888:
> @@ -543,6 +547,9 @@ static int gud_probe(struct usb_interface *intf, const struct usb_device_id *id)
>  			break;
>  		}
>  
> +		if (gud_xrgb8888 == formats_dev[i])
> +			xrgb8888_emulation_format = info;
> +
>  		fmt_buf_size = drm_format_info_min_pitch(info, 0, drm->mode_config.max_width) *
>  			       drm->mode_config.max_height;
>  		max_buffer_size = max(max_buffer_size, fmt_buf_size);
> @@ -559,7 +566,7 @@ static int gud_probe(struct usb_interface *intf, const struct usb_device_id *id)
>  	}
>  
>  	/* Prefer speed over color depth */
> -	if (rgb565_supported)
> +	if (!gud_xrgb8888 && rgb565_supported)
>  		drm->mode_config.preferred_depth = 16;
>  
>  	if (!xrgb8888_supported && xrgb8888_emulation_format) {
> -- 
> 2.32.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch