[PATCH] efifb: BGRT: Add check for new BGRT status field rotation bits

[Ard Biesheuvel]

On Tue, 11 Jun 2019 at 16:24, Hans de Goede <hdegoede at redhat.com> wrote:
>
> Hi,
>
> On 11-06-19 16:04, Ard Biesheuvel wrote:
> > On Mon, 10 Jun 2019 at 17:12, Ard Biesheuvel <ard.biesheuvel at linaro.org> wrote:
> >>
> >> On Wed, 29 May 2019 at 17:46, Hans de Goede <hdegoede at redhat.com> wrote:
> >>>
> >>> Starting with ACPI 6.2 bits 1 and 2 of the BGRT status field are no longer
> >>> reserved. These bits are now used to indicate if the image needs to be
> >>> rotated before being displayed.
> >>>
> >>> The efifb code does not support rotating the image before copying it to
> >>> the screen.
> >>>
> >>> This commit adds a check for these new bits and if they are set leaves the
> >>> fb contents as is instead of trying to use the un-rotated BGRT image.
> >>>
> >>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> >>
> >> Acked-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> >>
> >
> > BTW should we make sure that this patch and the efi-bgrt patch get
> > merged at the same time?
>
> The 2 patches are related but merging them at the same time is not
> necessary.
>
> > I guess the net result is just that we get
> > rid of some error in the log, but a rotated BMP will be ignored
> > otherwise.
>
> Right, worse case (if the bmp fits pre-rotation) it will be displayed
> rotated. Note on the one machine I'm aware of which uses these bits
> the bmp does not fit pre-rotation, so we end up triggering:
>
> error:
>          memunmap(bgrt_image);
>          pr_warn("efifb: Ignoring BGRT: unexpected or invalid BMP data\n");
> }
>

Doesn't that mean we may now end up breaking 'quiet', by exchanging a
pr_notice() in the efi-bgrt driver for a pr_warn() in this one?

> Which this patch replaces with hitting:
>
>          if (bgrt_tab.status & 0x06) {
>                  pr_info("efifb: BGRT rotation bits set, not showing boot graphics\n");
>                  return;
>          }
>
> Instead. So at least on the one machine I know of this is 99% cosmetic.
>
> > Or is it relevant for userland in some other way?
>
> No.
>
> Regards,
>
> Hans