Fwd: Rational for having CONFIG_FB_RADEON=m

[Mathieu Malaterre]

Hi Ben,

On Tue, Jun 14, 2016 at 1:15 PM, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
> On Tue, 2016-06-14 at 13:26 +1000, Michael Ellerman wrote:
>> On Mon, 2016-06-13 at 17:46 +0200, Mathieu Malaterre wrote:
>>
>> > 2. Try to fix `radeonfb` so that it is able to kick offb out of the
>> > way. Eg: https://lists.freedesktop.org/archives/dri-devel/2010-Augu
>> > st/002907.html
>> >
>> > From my understanding it would make sense to go for (2), since it
>> > would allow for proper support for CONFIG_FB_RADEON=m on PowerMac.
>> > In
>> > this case, would such patch be accepted ?
>>
>> Sounds like the right fix to me. Ben's patch above was merged, so
>> it's supposed
>> to kick out offb AFAICS, the fact that it can't seems like a
>
> Make sure you have CONFIG_VT_HW_CONSOLE_BINDING=y

Thanks I do have it.

What I was trying to say in my broken fr-english is that I would like
to patch `drivers/video/fbdev/aty/radeon_base.c` the same way you did
`drivers/gpu/drm/radeon/radeon_drv.c` a long time ago.

So that there is no possible confusion, I am attaching my WIP. I know
you must be very busy, but I would really appreciate if you could
review this patch and give me some clue(s) as to why
`pci_request_region` still fails even if the call to
`radeon_kick_out_firmware_fb` succeeds in kicking out `offb` (I am
left with an empty /proc/fb).

In this case dmesg properly reveals that OFfb was kicked out but still
the `radeonfb` could not succeed:

[...]
 bus: 'pci': add driver radeonfb
 bus: 'pci': driver_probe_device: matched device 0000:00:10.0 with
driver radeonfb
 bus: 'pci': really_probe: probing driver radeonfb with device 0000:00:10.0
 devices_kset: Moving 0000:00:10.0 to end of list
 radeonfb_pci_register BEGIN
 checking generic (9c008000 96000) vs hw (98000000 8000000)
 fb: switching to radeonfb from OFfb ATY,RockHo
 Console: switching to colour dummy device 80x25
 device: 'fb0': device_unregister
 PM: Removing info for No Bus:fb0
 device: 'fb0': device_create_release
 radeonfb 0000:00:10.0: enabling device (0006 -> 0007)
 device: 'vtcon1': device_unregister
 PM: Removing info for No Bus:vtcon1
 device: 'vtcon1': device_create_release
 radeonfb 0000:00:10.0: BAR 0: can't reserve [mem 0x98000000-0x9fffffff pref]
 radeonfb (0000:00:10.0): cannot request region 0.
 radeonfb: probe of 0000:00:10.0 failed with error -16
[...]

The only way I found to load `radeonfb` is to use offb:off in yaboot.

Regards and thanks for your time,
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