Re: [PATCH v2 5/9] drm/ast: Pin framebuffer BO during dirty update

[Sam Ravnborg <sam@ravnborg.org>]

Hi Thomas.

On Tue, Jun 11, 2019 at 03:03:40PM +0200, Thomas Zimmermann wrote:
> Another explicit lock operation of a GEM VRAM BO is located in AST's
> framebuffer update code. Instead of locking the BO, we pin it to wherever
> it is.
> 
> v2:
> 	* update with pin flag of 0
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/ast/ast_fb.c | 33 ++++++++++++++++-----------------
>  1 file changed, 16 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ast/ast_fb.c b/drivers/gpu/drm/ast/ast_fb.c
> index 05f45222b702..b404b51c2c55 100644
> --- a/drivers/gpu/drm/ast/ast_fb.c
> +++ b/drivers/gpu/drm/ast/ast_fb.c
> @@ -48,32 +48,31 @@ static void ast_dirty_update(struct ast_fbdev *afbdev,
>  			     int x, int y, int width, int height)
>  {
>  	int i;
> -	struct drm_gem_object *obj;
>  	struct drm_gem_vram_object *gbo;
>  	int src_offset, dst_offset;
>  	int bpp = afbdev->afb.base.format->cpp[0];
> -	int ret = -EBUSY;
> +	int ret;
>  	u8 *dst;
>  	bool unmap = false;
>  	bool store_for_later = false;
>  	int x2, y2;
>  	unsigned long flags;
>  
> -	obj = afbdev->afb.obj;
> -	gbo = drm_gem_vram_of_gem(obj);
> -
> -	/* Try to lock the BO. If we fail with -EBUSY then
> -	 * the BO is being moved and we should store up the
> -	 * damage until later.
> -	 */
> -	if (drm_can_sleep())
> -		ret = drm_gem_vram_lock(gbo, true);
> -	if (ret) {
> -		if (ret != -EBUSY)
> -			return;
> -
> +	gbo = drm_gem_vram_of_gem(afbdev->afb.obj);
> +
> +	if (drm_can_sleep()) {

While touching this code, anyway we could get rid of drm_can_sleep()?
I only ask because Daniel V. said that we should not use it.
This was some months ago during some ehader file clean-up, so nothing
in particular related to the ast driver.

	Sam

> +		/* We pin the BO so it won't be moved during the
> +		 * update. The actual location, video RAM or system
> +		 * memory, is not important.
> +		 */
> +		ret = drm_gem_vram_pin(gbo, 0);
> +		if (ret) {
> +			if (ret != -EBUSY)
> +				return;
> +			store_for_later = true;
> +		}
> +	} else
>  		store_for_later = true;
> -	}
>  
>  	x2 = x + width - 1;
>  	y2 = y + height - 1;
> @@ -126,7 +125,7 @@ static void ast_dirty_update(struct ast_fbdev *afbdev,
>  		drm_gem_vram_kunmap(gbo);
>  
>  out:
> -	drm_gem_vram_unlock(gbo);
> +	drm_gem_vram_unpin(gbo);
>  }
>  
>  static void ast_fillrect(struct fb_info *info,
> -- 
> 2.21.0
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