On 07/02/2023 12:17, Thomas Zimmermann wrote:
Hi
Am 07.02.23 um 11:53 schrieb Jocelyn Falempe:
During the driver conversion to shmem, there is a missing page shift when
computing the start address in GPU memory.
This leads to graphic garbage when connecting to the remote BMC,
depending
on the PCI start address.
Tested on a sr645 affected by this bug.
Fixes: f2fa5a99ca81 ("drm/ast: Convert ast to SHMEM")
Signed-off-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
---
drivers/gpu/drm/ast/ast_mode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ast/ast_mode.c
b/drivers/gpu/drm/ast/ast_mode.c
index c7443317c747..d75e4a7611b3 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 = ast->vram_base << PAGE_SHIFT;
That can't be the problem, I think. vram_base is already an address. [1]
In the old code, drm_gem_vram_pg_offset() returned a page index. So
shifting it to the left here is most likely incorrect.
Can you verify that the new offset is the same as the old one?
Yes, I was also a bit unsure about this fix.
In my case, with the old code:
PCI base address is 0xce000000
with old code:
start address (which is 24bits) was 0
with shmem code:
start address is 0x800000
So the additional page shift makes it 0, which fixes the display.
I was wondering if this start address is not an offset in the GPU
memory, and in this case the primary plane offset should always be 0 ?
Best regards,
Best regards
Thomas
[1]
https://elixir.bootlin.com/linux/v6.2-rc7/source/drivers/gpu/drm/ast/ast_mm.c#L96
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;
