Re: [PATCH v3] Fix loading of module radeonfb on PowerMac

[Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>]

Hi,

On Wednesday, February 01, 2017 07:55:25 AM Mathieu Malaterre wrote:
> Any chance this patch could be considered for inclusion this time ?
> 
> Thanks
> 
> On Wed, Nov 23, 2016 at 8:26 AM, Mathieu Malaterre <malat@debian.org> 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.
> >
> > The problem is that offb call pci_request_region first, and then radeonfb
> > tries to do it, and since one is trying to take over from the other, it can't
> > do that because the area is already reserved.
> >
> > It should be noticed that `offb_destroy` is never called which explain the
> > need to skip error detection on the radeonfb side.
> >
> > Signed-off-by: Mathieu Malaterre <malat@debian.org>
> > Link: https://bugs.debian.org/826629#57
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id\x119741
> > Suggested-by: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
> > ---
> >
> > v2: Remove compilation warning
> >
> > v3: Hide error messages on PPC
> >
> >  drivers/video/fbdev/aty/radeon_base.c | 27 +++++++++++++++++++++++++++
> >  1 file changed, 27 insertions(+)
> >
> > diff --git a/drivers/video/fbdev/aty/radeon_base.c b/drivers/video/fbdev/aty/radeon_base.c
> > index 218339a..837c86a 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)
> > @@ -2314,20 +2330,29 @@ 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");
> > +  /* this is not an error on PowerMac where offb already requested mem regions */
> > +#ifndef CONFIG_PPC

This doesn't look correct:

- PPC is not only PowerMac and offb supports more cards
  than radeon (while radeonfb can be used for secondary
  graphics card)

- offb can be disabled

  (i.e. in CONFIG_FB_OF=n && CONFIG_FB_RADEON=y case error
  checking will be missing now)

The last put_fb_info() on fb_info should call ->fb_destroy
(offb_destroy in our case) and remove_conflicting_framebuffers()
is calling put_fb_info() so there is some extra reference on
fb_info somewhere preventing it from going away.

Please look into fixing this.

> >         if (ret < 0) {
> >                 printk( KERN_ERR "radeonfb (%s): cannot request region 0.\n",
> >                         pci_name(rinfo->pdev));
> >                 goto err_release_fb;
> >         }
> > +#endif
> >
> >         ret = pci_request_region(pdev, 2, "radeonfb mmio");
> > +#ifndef CONFIG_PPC
> >         if (ret < 0) {
> >                 printk( KERN_ERR "radeonfb (%s): cannot request region 2.\n",
> >                         pci_name(rinfo->pdev));
> >                 goto err_release_pci0;
> >         }
> > +#endif
> >
> >         /* map the regions */
> >         rinfo->mmio_base = ioremap(rinfo->mmio_base_phys, RADEON_REGSIZE);
> > @@ -2511,10 +2536,12 @@ 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;
> > --
> > 2.1.4

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics