[Intel-gfx] i915.fastboot bug report - not working on coreboot

[Charles Devereaux]

Hello

(IIRC, there is no VBT  or INT 10H support yet in coreboot native video
init)

Regarding EDID, it's handled from intel_gma_init in
coreboot/src/northbridge/intel/i945/gma.c.
The only thing I see that could be linked to a preferred mode is in
decode_edid from coreboot/src/lib/edid.c :
                if (edid[0x18] & 0x02) {
                        printk(BIOS_SPEW, "First detailed timing is
preferred timing\n");
                        has_preferred_timing = 1;
                }
(...)
                /* detailed timings */
                printk(BIOS_SPEW, "Detailed timings\n");
                has_valid_detailed_blocks = detailed_block(out, edid +
0x36, 0);
                if (has_preferred_timing && !did_detailed_timing)
                        has_preferred_timing = 0; /* not really accurate...
*/

Maybe disabling has_preferred_timing  if there are no did_detailed_timing
is wrong?


I'm sorry but my understanding of coreboot video initialization is too
limited.  Gluglug, could you suggest someone that could help on that issue?
Addressing it will enable i915.fastboot support.

Jesse, if meanwhile you can send me fastboot patch to handle that, I will
be happy to test it and report the result.

(At the moment, even if i915.fastboot fails as reported above, I get some
blinking in Xorg, which is resolved after going back and forth to a text
console)

Thanks
Charles

On Thu, Oct 30, 2014 at 5:34 PM, Jesse Barnes <jbarnes at virtuousgeek.org>
wrote:

> On Thu, 23 Oct 2014 16:44:26 -0400
> Charles Devereaux <intelgfx at guylhem.net> wrote:
>
> > [    0.529733] [drm:intel_set_config_compute_mode_changes], modes are
> > different, full mode set
> > [    0.529736] [drm:drm_mode_debug_printmodeline], Modeline 0:"" 0 54167
> > 1024 1048 1184 1344 768 771 777 806 0x0 0xa
> > [    0.529740] [drm:drm_mode_debug_printmodeline], Modeline 11:"1024x768"
> > 60 65000 1024 1048 1184 1344 768 771 777 806 0x48 0xa
>
> This looks like the issue.  The BIOS programs a slightly different
> 1024x768 mode than what the kernel tries to apply.  Looks like reduced
> vs non-reduced blanking approximately.
>
> We could adjust the fastboot code to handle that, or change coreboot to
> use the preferred mode from the EDID of the display or make the VBT
> match, which is presumably what the kernel is using.
>
> --
> Jesse Barnes, Intel Open Source Technology Center
>
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