On Fri, Aug 28, 2015 at 01:12:19PM +0100, Matt Fleming wrote:
> From: Matt Fleming <matt.flem...@intel.com>
>
> The EFI Graphics Output Protocol uses 64-bit frame buffer addresses
> but these get truncated to 32-bit by the EFI boot stub when storing
> the address in the 'lfb_base' field of 'struct screen_info'.
>
> Add a 'ext_lfb_base' field for the upper 32-bits of the frame buffer
> address and set VIDEO_TYPE_CAPABILITY_64BIT_BASE when the field is
> useable.
>
> It turns out that the reason no one has required this support so far
> is that there's actually code in tianocore to "downgrade" PCI
> resources that have option ROMs and 64-bit BARS from 64-bit to 32-bit
> to cope with legacy option ROMs that can't handle 64-bit addresses.
> The upshot is that basically all GOP devices in the wild use a 32-bit
> frame buffer address.
>
> Still, it is possible to build firmware that uses a full 64-bit GOP
> frame buffer address. Chad did, which led to him reporting this issue.
>
> Add support in anticipation of GOP devices using 64-bit addresses more
> widely, and so that efifb works out of the box when that happens.
>
> Reported-by: Chad Page <chad.p...@znyx.com>
> Cc: Pete Hawkins <pete.hawk...@znyx.com>
> Cc: Peter Jones <pjo...@redhat.com>
> Cc: Matthew Garrett <mj...@srcf.ucam.org>
> Signed-off-by: Matt Fleming <matt.flem...@intel.com>
Looks good to me.
Acked-by: Peter Jones <pjo...@redhat.com>
--
Peter
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
