Thomas Huth <thuth@xxxxxxxxxx> writes:
Hello Thomas,
> Starting with kernel 6.7, the framebuffer text console is not working
> anymore with the virtio-gpu device on s390x hosts. Such big endian fb
> devices are usinga different pixel ordering than little endian devices,
> e.g. DRM_FORMAT_BGRX8888 instead of DRM_FORMAT_XRGB8888.
>
> This used to work fine as long as drm_client_buffer_addfb() was still
> calling drm_mode_addfb() which called drm_driver_legacy_fb_format()
> internally to get the right format. But drm_client_buffer_addfb() has
> recently been reworked to call drm_mode_addfb2() instead with the
> format value that has been passed to it as a parameter (see commit
> 6ae2ff23aa43 ("drm/client: Convert drm_client_buffer_addfb() to drm_mode_addfb2()").
>
> That format parameter is determined in drm_fbdev_generic_helper_fb_probe()
> via the drm_mode_legacy_fb_format() function - which only generates
> formats suitable for little endian devices. So to fix this issue
> switch to drm_driver_legacy_fb_format() here instead to take the
> device endianness into consideration.
>
> Fixes: 6ae2ff23aa43 ("drm/client: Convert drm_client_buffer_addfb() to drm_mode_addfb2()")
> Closes: https://issues.redhat.com/browse/RHEL-45158
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_fbdev_generic.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c
> index 97e579c33d84..1e200d815e1a 100644
> --- a/drivers/gpu/drm/drm_fbdev_generic.c
> +++ b/drivers/gpu/drm/drm_fbdev_generic.c
> @@ -84,7 +84,8 @@ static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper,
> sizes->surface_width, sizes->surface_height,
> sizes->surface_bpp);
>
> - format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
> + format = drm_driver_legacy_fb_format(dev, sizes->surface_bpp,
> + sizes->surface_depth);
> buffer = drm_client_framebuffer_create(client, sizes->surface_width,
> sizes->surface_height, format);
> if (IS_ERR(buffer))
Indeed. Thanks a lot for the detailed explanation and the patch.
Your fix makes sense to me.
Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
--
Best regards,
Javier Martinez Canillas
Core Platforms
Red Hat
