[PATCH 2/3] efi_loader: GOP: Add 30bpp support

[Mark Kettenis]

> From: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Date: Fri, 17 Sep 2021 13:29:06 +0200
> 
> On 9/17/21 11:23 AM, Mark Kettenis wrote:
> >> From: Heinrich Schuchardt <xypron.glpk at gmx.de>
> >> Date: Fri, 17 Sep 2021 04:56:31 +0200
> >
> > Hi Heinrich,
> >
> >> On 9/16/21 3:01 PM, Mark Kettenis wrote:
> >>> Provide correct framebuffer information for 30bpp modes.
> >>
> >> This is not enough to get a correct GOP implementation for the 30bpp mode.
> >>
> >> Have a look at efi_gop_pixel efi_vid16_to_blt_col() and
> >> efi_blt_col_to_vid16() and where they are used.
> >
> > Ah right.  This does indeed not support EFI_GRAPHICS_OUTPUT_PROTOCOL.Blt()
> > correctly.  I shouldn't be too hard to translate between XRGB2101010
> > and XRGB8888.  Any ideas how I could test that code?
> 
> setenv efi_selftest block image transfer
> bootefi selftest
> 
> should show an animated submarine with yellow portholes similar to
> 
> https://gist.github.com/xypron/7e1f73408465da71e3ef946250e76776#file-sub-png
> 
> Best regards

Cool thanks.  Looks like my implementation works!  I'll wait a bit for
feedback on the other diffs in this series before sending a v2 with that.

Cheers,

Mark

> >>> Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> >>> ---
> >>>    lib/efi_loader/efi_gop.c | 10 ++++++++++
> >>>    1 file changed, 10 insertions(+)
> >>>
> >>> diff --git a/lib/efi_loader/efi_gop.c b/lib/efi_loader/efi_gop.c
> >>> index 1206b2d7a2..42bf49b184 100644
> >>> --- a/lib/efi_loader/efi_gop.c
> >>> +++ b/lib/efi_loader/efi_gop.c
> >>> @@ -227,6 +227,7 @@ static efi_uintn_t gop_get_bpp(struct efi_gop *this)
> >>>
> >>>    	switch (gopobj->bpix) {
> >>>    #ifdef CONFIG_DM_VIDEO
> >>> +	case VIDEO_BPP30:
> >>>    	case VIDEO_BPP32:
> >>>    #else
> >>>    	case LCD_COLOR32:
> >>> @@ -468,6 +469,7 @@ efi_status_t efi_gop_register(void)
> >>>    	switch (bpix) {
> >>>    #ifdef CONFIG_DM_VIDEO
> >>>    	case VIDEO_BPP16:
> >>> +	case VIDEO_BPP30:
> >>>    	case VIDEO_BPP32:
> >>>    #else
> >>>    	case LCD_COLOR32:
> >>> @@ -518,6 +520,14 @@ efi_status_t efi_gop_register(void)
> >>>    #endif
> >>>    	{
> >>>    		gopobj->info.pixel_format = EFI_GOT_BGRA8;
> >>> +#ifdef CONFIG_DM_VIDEO
> >>
> >> This symbol is not 30bpp specific. Is there a Kconfig variable that we
> >> can use to hide 30bpp support where it is not needed?
> >
> > I quite deliberately didn't add a separate config option for 30bpp as
> > there is very little code that is added to the already existing 32bpp
> > code.  In a sense 30bpp is just a different submode of the 32bpp
> > support with just a different color map, so I thought it made sense to
> > group it under CONFIG_VIDEO_32BPP.  I did initially consider adding a
> > separate config option for it, but it quickly turns into an #ifdef
> > maze that makes it hard to understand the code.
> >
> > The CONFIG_DM_VIDEO check is just there to make sure the 30bpp is only
> > offered in the DM model.  Based on recent discussions I expect the
> > !CONFIG_DM_VIDEO case to disappear in the near feature so adding 30bpp
> > support for the non-DM case doesn't make sense.
> >
> > The EFI GOP code currently doesn't check the CONFIG_VIDEO_BPP16 and
> > CONFIG_VIDEO_BPP32 defines to see which of these modes are enabled
> > within U-Boot, so we don't "hide" 16bpp support on platforms that just
> > support 32bpp either.
> >
> >> Which modes does the M1 support?
> >
> > We're not sure.  It does support at least 8-bit (32bpp) and 10-bit
> > (30bpp) color depth modes.  But the firmware tends to come up with
> > 10-bit color depth whenever it can and I'm not planning to add support
> > for changing the framebuffer mode on the M1, since the interface to do
> > that is "interesting" [1].
> >
> > [1] See Alyssa Rozenzweig's talk at XDC 2021,
> >      https://www.youtube.com/watch?v=uTZISTjqy9Q
> >>
> >>> +	} else if (bpix == VIDEO_BPP30) {
> >>> +		gopobj->info.pixel_format = EFI_GOT_BITMASK;
> >>> +		gopobj->info.pixel_bitmask[0] = 0x3ff00000; /* red */
> >>> +		gopobj->info.pixel_bitmask[1] = 0x000ffc00; /* green */
> >>> +		gopobj->info.pixel_bitmask[2] = 0x000003ff; /* blue */
> >>> +		gopobj->info.pixel_bitmask[3] = 0xc0000000; /* reserved */
> >>> +#endif
> >>>    	} else {
> >>>    		gopobj->info.pixel_format = EFI_GOT_BITMASK;
> >>>    		gopobj->info.pixel_bitmask[0] = 0xf800; /* red */
> >>>
> >>
> >>
>