Tomi,

On Tue, Nov 15, 2016 at 12:46 PM, Tomi Valkeinen [off-list ref] wrote:

Hi,

On 14/11/16 21:59, Mathieu Malaterre wrote:

quoted

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 <redacted>
Link: https://bugs.debian.org/826629#57
Link: https://bugzilla.kernel.org/show_bug.cgi?id=119741
Suggested-by: Lennart Sorensen <redacted>
---

Please always have a changelog in patch new revisions. For individual
patches, you can insert the changes here.

quoted

 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.

quoted

      }

      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.

quoted

      }

      /* 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