[PATCH v3] Fix loading of module radeonfb on PowerMac

[Mathieu Malaterre <malat@debian.org>]

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
 	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