Hi Javier Am 05.07.23 um 10:34 schrieb Javier Martinez Canillas:
Thomas Zimmermann <tzimmermann@xxxxxxx> writes:Set fbdev default flags FBNFO_DEFAULT and mark the framebuffer with FBINFO_VIRTFB. The framebuffer range is in DMA-able memory and should be accessed with the CPU's regular memory ops. Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> Cc: Thierry Reding <thierry.reding@xxxxxxxxx> Cc: Mikko Perttunen <mperttunen@xxxxxxxxxx> --- drivers/gpu/drm/tegra/fbdev.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/tegra/fbdev.c b/drivers/gpu/drm/tegra/fbdev.c index 82577b7c88da..8074430c52f1 100644 --- a/drivers/gpu/drm/tegra/fbdev.c +++ b/drivers/gpu/drm/tegra/fbdev.c @@ -103,6 +103,8 @@ static int tegra_fbdev_probe(struct drm_fb_helper *helper, return PTR_ERR(info); }+ info->flags = FBINFO_DEFAULT;+ fb = tegra_fb_alloc(drm, &cmd, &bo, 1); if (IS_ERR(fb)) { err = PTR_ERR(fb); @@ -132,6 +134,7 @@ static int tegra_fbdev_probe(struct drm_fb_helper *helper, } }+ info->flags |= FBINFO_VIRTFB;I see that all fbdev drivers just do: info->flags = FBINFO_FLAG_DEFAULT | FBINFO_VIRTFB Guess you are doing in two assignments to be consistent with drm_fbdev_dma.c ? I was just curious about the rationale for setting the flags in two steps.
The _DEFAULT flag is really just a zero. And the other flags describe different aspects of the framebuffer. I think it makes sense to set the flags together with the respective state. For example, _VIRTFB is set next to ->screen_buffer, because they belong together.
_VIRTFB is currently only used in defio code at https://elixir.bootlin.com/linux/latest/source/drivers/video/fbdev/core/fb_defio.c#L232I think the fbdev I/O helpers should also test this flag after all drivers have been annotated correctly. For example, fb_io_read() would WARN_ONCE if the _VIRTFB flag has been set; and fb_sys_read() would warn if it hasn't been set. For the read helpers, it also makes sense to WARN_ONCE if the _READS_FAST flag has not been set.
Best regards Thomas
Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstrasse 146, 90461 Nuernberg, Germany GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB 36809 (AG Nuernberg)
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