Re: eMac video modes

[Ed Robbins <edd.robbins@googlemail.com>]

On Fri, 3 Apr 2020 at 22:08, John Paul Adrian Glaubitz
<glaubitz@physik.fu-berlin.de> wrote:
>
> On 4/3/20 10:58 PM, Ed Robbins wrote:
> >> 2. I used switchresx on mac OS X to export all the video modes of the eMac
> >> monitor, rewrote them into modelines, and then used [3] to generate an EDID
> >> bin file (1280x960.bin). It only contains the video mode for the highest
> >> resolution, 1280x960@72Hz. The modeline is "1280x960" 122.24 1280 1328
> >> 1424 1696 960 961 964 1002 +hsync +vsync.
> >> 3. Copy the EDID bin file to /lib/firmware/edid/1280x960.bin
> >> 4. Create /usr/share/initramfs-tools/hooks/edid with contents as below
> >> (looking at it now, I guess this could actually be done with a one line
> >> "install -D" but anyway...)
> >>
> >> #!/bin/sh
> >> mkdir -p ${DESTDIR}/lib/firmware/edid
> >> cp -pnL /lib/firmware/edid/1280x960.bin
> >> ${DESTDIR}/lib/firmware/edid/1280x960.bin
> >> chmod 644 ${DESTDIR}/lib/firmware/edid/1280x960.bin
> >>
> >> 5. Run "update-initramfs -u" to create the new initramfs
>
> This sounds like a reasonable approach. We would just need to find a
> firmware package where the EDID file fits in, see:
>
> > https://packages.debian.org/search?suite=buster&section=all&arch=any&searchon=names&keywords=firmware

The only place I can see it fitting is firmware-linux-free, but it is
not that similar to other firmwares in that package, which look to all
be firmware in the sense of executable code. However, I don't know if
that distinction is important: it is free firmware for the Linux
kernel.

>
> > Alternatively, I think the attached kernel patch will do the same thing.
> > You would then boot with the parameter:
> > drm.edid_firmware=edid/emac_1280x960.bin
> >
> > The disadvantage is that it wont work for any kernel, and I guess it is
> > unlikely to be accepted upstream by the kernel devs. However most emac
> > users will not be building mainline kernels, and I guess you are already
> > patching the kernel for powerpc? So this might be the best way, even if
> > users have to manually add the boot parameter.
>
> No, we're not rolling a custon kernel. Debian for PowerPC uses the Debian
> stock kernel, with all the patches Debian needs.
>
> It could be added as a patch to the kernel package, but it would have be
> carried around forever which I don't think is acceptable.

I agree that the other solution is neater, just wanted to check a
kernel patch wasn't easier for you.

Best,
Ed

>
> Adrian
>
> --
>  .''`.  John Paul Adrian Glaubitz
> : :' :  Debian Developer - glaubitz@debian.org
> `. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
>   `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913