[PATCH v3] drm/ast: Fix start address computation

[Thomas Zimmermann]

Am 09.02.23 um 10:44 schrieb Jocelyn Falempe:
> During the driver conversion to shmem, the start address for the
> scanout buffer was set to the base PCI address.
> In most cases it works because only the lower 24bits are used, and
> due to alignment it was almost always 0.
> But on some unlucky hardware, it's not the case, and some unitilized

'uninitialized'

> memory is displayed on the BMC.
> With shmem, the primary plane is always at offset 0 in GPU memory.
> 
>   * v2: rewrite the patch to set the offset to 0. (Thomas Zimmermann)
>   * v3: move the change to plane_init() and also fix the cursor plane.
>         (Jammy Huang)
> 
> Tested on a sr645 affected by this bug.
> 
> Fixes: f2fa5a99ca81 ("drm/ast: Convert ast to SHMEM")
> Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>

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

> ---
>   drivers/gpu/drm/ast/ast_mode.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> index c7443317c747..66a4a41c3fe9 100644
> --- a/drivers/gpu/drm/ast/ast_mode.c
> +++ b/drivers/gpu/drm/ast/ast_mode.c
> @@ -714,7 +714,7 @@ static int ast_primary_plane_init(struct ast_private *ast)
>   	struct ast_plane *ast_primary_plane = &ast->primary_plane;
>   	struct drm_plane *primary_plane = &ast_primary_plane->base;
>   	void __iomem *vaddr = ast->vram;
> -	u64 offset = ast->vram_base;
> +	u64 offset = 0; /* with shmem, the primary plane is always at offset 0 */
>   	unsigned long cursor_size = roundup(AST_HWC_SIZE + AST_HWC_SIGNATURE_SIZE, PAGE_SIZE);
>   	unsigned long size = ast->vram_fb_available - cursor_size;
>   	int ret;
> @@ -972,7 +972,7 @@ static int ast_cursor_plane_init(struct ast_private *ast)
>   		return -ENOMEM;
>   
>   	vaddr = ast->vram + ast->vram_fb_available - size;
> -	offset = ast->vram_base + ast->vram_fb_available - size;
> +	offset = ast->vram_fb_available - size;
>   
>   	ret = ast_plane_init(dev, ast_cursor_plane, vaddr, offset, size,
>   			     0x01, &ast_cursor_plane_funcs,

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