Thomas Zimmermann <tzimmermann@xxxxxxx> writes:
Hello Thomas,
> Framebuffer memory is allocated via vmalloc() from non-contiguous
It's vmalloc() true, but through vzmalloc() so I would mention that
function instead in the commit message.
> physical pages. The physical framebuffer start address is therefore
> meaningless. Do not set it.
>
> The value is not used within the kernel and only exported to userspace
> on dedicated ARM configs. No functional change is expected.
>
How's that info used? Does user-space assumes that the whole memory range
is contiguous in physical memory or just cares about the phyisical start
address ?
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Fixes: a5b44c4adb16 ("drm/fbdev-generic: Always use shadow buffering")
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> Cc: Zack Rusin <zackr@xxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v6.4+
> ---
> drivers/gpu/drm/drm_fbdev_generic.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
> index d647d89764cb9..b4659cd6285ab 100644
> --- a/drivers/gpu/drm/drm_fbdev_generic.c
> +++ b/drivers/gpu/drm/drm_fbdev_generic.c
> @@ -113,7 +113,6 @@ static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper,
> /* screen */
> info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
> info->screen_buffer = screen_buffer;
> - info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
> info->fix.smem_len = screen_size;
>
Makes sense:
Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
What about drivers/gpu/drm/drm_fb_helper.c btw? Since the memory range
allocated may not be physically contiguous if a platform uses an IOMMU ?
Asking because I don't really know how these exported values are used...
I just know that is when the CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM is enabled.
--
Best regards,
Javier Martinez Canillas
Core Platforms
Red Hat
