Re: [PATCH v2] drm/sysfb: Use iosys_map_memset() to clear buffer

From: Thomas Zimmermann

Date: Wed Sep 09 2026 - 04:48:52 EST




Am 03.09.26 um 10:48 schrieb Chen-Yu Tsai:
The atomic disable in drm/sysfb currently clears the buffer using
memset_io(). Since the mapping is provided in a |struct iosys_map|,
it is better to use the related API instead of extracting the vaddr.
This is mentioned as a TODO item.

Switch to iosys_map_memset(), which takes the mapping as well as an
offset into the mapping.

Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>

Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>

---
Changes since v1:
- Rebased onto drm-misc-next
- second patch is gone as it was already implemented
---
drivers/gpu/drm/sysfb/drm_sysfb_modeset.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/sysfb/drm_sysfb_modeset.c b/drivers/gpu/drm/sysfb/drm_sysfb_modeset.c
index b92cc4b7d2ad..13df0925163a 100644
--- a/drivers/gpu/drm/sysfb/drm_sysfb_modeset.c
+++ b/drivers/gpu/drm/sysfb/drm_sysfb_modeset.c
@@ -375,8 +375,6 @@ void drm_sysfb_plane_helper_atomic_disable(struct drm_plane *plane,
{
struct drm_device *dev = plane->dev;
struct drm_sysfb_device *sysfb = to_drm_sysfb_device(dev);
- struct iosys_map dst = sysfb->fb_addr;
- void __iomem *dst_vmap = dst.vaddr_iomem; /* TODO: Use mapping abstraction */
unsigned int dst_pitch = sysfb->fb_pitch;
const struct drm_format_info *dst_format = sysfb->fb_format;
struct drm_rect dst_clip;
@@ -396,10 +394,8 @@ void drm_sysfb_plane_helper_atomic_disable(struct drm_plane *plane,
return;
/* Clear buffer to black if disabled */
- for (i = 0; i < lines; ++i) {
- memset_io(dst_vmap, 0, dst_size);
- dst_vmap += dst_pitch;
- }
+ for (i = 0; i < lines; ++i)
+ iosys_map_memset(&sysfb->fb_addr, dst_pitch * i, 0, dst_size);
drm_dev_exit(idx);
}

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)