Messages in this thread | | | Date | Wed, 29 Mar 2023 18:48:27 +0800 | Subject | Re: [PATCH] drm/fbdev-generic: optimize out a redundant assignment clause | From | Sui Jingfeng <> |
| |
On 2023/3/29 17:04, 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@189.cn> >> --- >> 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. > > 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 > 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. > Ok. that's fine then.
> Best regards > Thomas > >> drm_client_buffer_vunmap(buffer); >
| |