On 2023/3/30 15:26, Thomas Zimmermann wrote:
Hi
Am 30.03.23 um 09:17 schrieb Sui Jingfeng:
Hi,
On 2023/3/30 14:57, Thomas Zimmermann wrote:
Hi
Am 30.03.23 um 06:17 schrieb Lucas De Marchi:
On Wed, Mar 29, 2023 at 11:04:17AM +0200, Thomas Zimmermann wrote:
(cc'ing Lucas)
Hi
Am 25.03.23 um 08:46 schrieb Sui Jingfeng:
The assignment already done in drm_client_buffer_vmap(),
just trival clean, no functional change.
Signed-off-by: Sui Jingfeng <15330273260@xxxxxx>
---
drivers/gpu/drm/drm_fbdev_generic.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_fbdev_generic.c
b/drivers/gpu/drm/drm_fbdev_generic.c
index 4d6325e91565..1da48e71c7f1 100644
--- a/drivers/gpu/drm/drm_fbdev_generic.c
+++ b/drivers/gpu/drm/drm_fbdev_generic.c
@@ -282,7 +282,7 @@ static int drm_fbdev_damage_blit(struct
drm_fb_helper *fb_helper,
struct drm_clip_rect *clip)
{
struct drm_client_buffer *buffer = fb_helper->buffer;
- struct iosys_map map, dst;
+ struct iosys_map map;
int ret;
/*
@@ -302,8 +302,7 @@ static int drm_fbdev_damage_blit(struct
drm_fb_helper *fb_helper,
if (ret)
goto out;
- dst = map;
- drm_fbdev_damage_blit_real(fb_helper, clip, &dst);
+ drm_fbdev_damage_blit_real(fb_helper, clip, &map);
I see what you're doing and it's probably correct in this case.
But there's a larger issue with this iosys interfaces. Sometimes
the address has to be modified (see calls of iosys_map_incr()).
That can prevent incorrect uses of the mapping in other places,
especially in unmap code.
using a initializer for the cases it's needed IMO would make these
kind
of problems go away, because then the intent is explicit
I think it would make sense to consider a separate structure for
the I/O location. The buffer as a whole would still be represented
by struct iosys_map. And that new structure, let's call it struct
iosys_ptr, would point to an actual location within the buffer's
sounds fine to me, but I'd have to take a deeper look later (or when
someone writes the patch). It seems we'd replicate almost the entire
API to just accomodate the 2 structs. And the different types will
lead
to confusion when one or the other should be used
I think we can split the current interface onto two categories:
mapping and I/O. The former would use iosys_map and the latter would
use iosys_ptr. And we'd need a helper that turns gets a ptr for a
given map.
If I find the tine, I'll probably type up a patch.
Here i fix a typo, 'tine' -> 'time'
As far as i can see, they are two major type of memory in the system.
System memory or VRAM, for the gpu with dedicate video ram, VRAM is
belong to the IO memory category.
But there are system choose carveout part of system ram as video
ram(i915?, for example).
the name iosys_map and iosys_ptr have no difference at the first
sight, tell me which one is for mapping system ram
and which one is for mapping vram?
As you say correctly, graphics buffers and be in various locations.
They can even move between I/O and system memory. The idea behind
iosys_map ("I/O and/or system mapping") is that it's a single
interface that can handle both.
They are all pointers in its very nature.
The hard part to make ensure that iosys_map can not be replaced with
iosys_ptr,
They should not overlap in functional, I meant.
Best regards
Thomas
Best regards
Thomas
thanks
Lucas De Marchi
memory range. A few locations and helpers would need changes, but
there are not so many callers that it's an issue. This would also
allow for a few debugging tests that ensure that iosys_ptr always
operates within the bounds of an iosys_map.
I've long considered this idea, but there was no pressure to work
on it. Maybe now.
Best regards
Thomas
drm_client_buffer_vunmap(buffer);
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
