[PATCH v2] Fix loading of module radeonfb on PowerMac

[Mathieu Malaterre]

Tomi,

On Tue, Nov 15, 2016 at 12:46 PM, Tomi Valkeinen <tomi.valkeinen at ti.com> wrote:
> Hi,
>
> On 14/11/16 21:59, Mathieu Malaterre wrote:
>> When the linux kernel is build with (typical kernel ship with Debian
>> installer):
>>
>> CONFIG_FB_OF=y
>> CONFIG_VT_HW_CONSOLE_BINDING=y
>> CONFIG_FB_RADEON=m
>>
>> The offb driver takes precedence over module radeonfb. It is then
>> impossible to load the module, error reported is:
>>
>> [   96.551486] radeonfb 0000:00:10.0: enabling device (0006 -> 0007)
>> [   96.551526] radeonfb 0000:00:10.0: BAR 0: can't reserve [mem 0x98000000-0x9fffffff pref]
>> [   96.551531] radeonfb (0000:00:10.0): cannot request region 0.
>> [   96.551545] radeonfb: probe of 0000:00:10.0 failed with error -16
>>
>> This patch reproduce the behavior of the module radeon, so as to make it
>> possible to load radeonfb when offb is first loaded.
>>
>> It should be noticed that `offb_destroy` is never called which explain the
>> need to skip error detection on the radeon side.
>>
>> Signed-off-by: Mathieu Malaterre <malat at debian.org>
>> Link: https://bugs.debian.org/826629#57
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=119741
>> Suggested-by: Lennart Sorensen <lsorense at csclub.uwaterloo.ca>
>> ---
>
> Please always have a changelog in patch new revisions. For individual
> patches, you can insert the changes here.
>
>>  drivers/video/fbdev/aty/radeon_base.c | 26 ++++++++++++++++++++++++++
>>  1 file changed, 26 insertions(+)
>>
>> diff --git a/drivers/video/fbdev/aty/radeon_base.c b/drivers/video/fbdev/aty/radeon_base.c
>> index 218339a..84d634b 100644
>> --- a/drivers/video/fbdev/aty/radeon_base.c
>> +++ b/drivers/video/fbdev/aty/radeon_base.c
>> @@ -2259,6 +2259,22 @@ static struct bin_attribute edid2_attr = {
>>       .read   = radeon_show_edid2,
>>  };
>>
>> +static int radeon_kick_out_firmware_fb(struct pci_dev *pdev)
>> +{
>> +     struct apertures_struct *ap;
>> +
>> +     ap = alloc_apertures(1);
>> +     if (!ap)
>> +             return -ENOMEM;
>> +
>> +     ap->ranges[0].base = pci_resource_start(pdev, 0);
>> +     ap->ranges[0].size = pci_resource_len(pdev, 0);
>> +
>> +     remove_conflicting_framebuffers(ap, KBUILD_MODNAME, false);
>> +     kfree(ap);
>> +
>> +     return 0;
>> +}
>>
>>  static int radeonfb_pci_register(struct pci_dev *pdev,
>>                                const struct pci_device_id *ent)
>> @@ -2314,19 +2330,27 @@ static int radeonfb_pci_register(struct pci_dev *pdev,
>>       rinfo->fb_base_phys = pci_resource_start (pdev, 0);
>>       rinfo->mmio_base_phys = pci_resource_start (pdev, 2);
>>
>> +     ret = radeon_kick_out_firmware_fb(pdev);
>> +     if (ret)
>> +             return ret;
>> +
>>       /* request the mem regions */
>>       ret = pci_request_region(pdev, 0, "radeonfb framebuffer");
>>       if (ret < 0) {
>>               printk( KERN_ERR "radeonfb (%s): cannot request region 0.\n",
>>                       pci_name(rinfo->pdev));
>> +#ifndef CONFIG_PPC
>>               goto err_release_fb;
>> +#endif
>
> If this is not a problem on PPC, the kernel shouldn't print an error either.
>
>>       }
>>
>>       ret = pci_request_region(pdev, 2, "radeonfb mmio");
>>       if (ret < 0) {
>>               printk( KERN_ERR "radeonfb (%s): cannot request region 2.\n",
>>                       pci_name(rinfo->pdev));
>> +#ifndef CONFIG_PPC
>>               goto err_release_pci0;
>> +#endif
>
> Same here.
>
>>       }
>>
>>       /* map the regions */
>> @@ -2511,10 +2535,12 @@ static int radeonfb_pci_register(struct pci_dev *pdev,
>>       iounmap(rinfo->mmio_base);
>>  err_release_pci2:
>>       pci_release_region(pdev, 2);
>> +#ifndef CONFIG_PPC
>>  err_release_pci0:
>>       pci_release_region(pdev, 0);
>>  err_release_fb:
>>          framebuffer_release(info);
>> +#endif
>>  err_disable:
>>  err_out:
>>       return ret;
>>
>
> So I don't quite follow what's going on here. Why the CONFIG_PPC
> conditionals? Is this problem only with OFFB and only with PPC?

The radeonfb fails to load only (conflict with offb):
- when on PPC (PMAC actually)
- when compiled as module (CONFIG_FB_RADEON=y is OK)

> And I think the code itself should have comments on this rather strange
> behavior: the driver fails to get HW resources, but decides to ignore
> the failure on PPC.

Actually you are right, I missed configuration such as Pegasos[0]
machine (no openfirmware-framebuffer implemented in their firmware at
all). So I cannot simply assume that offb already allocated stuff on
all PPC out there.

Will resent a v3 with proper changelog ASAP.

[0] https://en.wikipedia.org/wiki/Pegasos