On Tuesday, January 30, 2018 02:14:10 PM Mathieu Malaterre wrote:
Bartlomiej,
On Wed, Jan 3, 2018 at 3:47 PM, Bartlomiej Zolnierkiewicz
[off-list ref] wrote:
quoted
On Thursday, December 21, 2017 11:07:56 PM 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.
This still needs to be explained more, from my last mail:
"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."
I am not familiar with the fb stuff internals but here is what I see:
# modprobe radeonfb
leads to:
[ 52.058546] bus: 'pci': add driver radeonfb
[ 52.058588] bus: 'pci': driver_probe_device: matched device
0000:00:10.0 with driver radeonfb
[ 52.058595] bus: 'pci': really_probe: probing driver radeonfb with
device 0000:00:10.0
[ 52.058608] devices_kset: Moving 0000:00:10.0 to end of list
[ 52.058613] radeonfb_pci_register BEGIN
[ 52.058634] radeonfb 0000:00:10.0: enabling device (0006 -> 0007)
<at this point radeon_kick_out_firmware_fb is called>
[ 52.058666] checking generic (9c008000 96000) vs hw (98000000 8000000)
[ 52.058667] fb: switching to radeonfb from OFfb ATY,RockHo
[ 52.058844] Console: switching to colour dummy device 80x25
[ 52.058860] device: 'fb0': device_unregister
[ 52.058956] PM: Removing info for No Bus:fb0
[ 52.059014] device: 'fb0': device_create_release
<a call to do_unregister_framebuffer is done>
<put_fb_info is done with a count=2 and dev=NULL>
[ 52.059048] device: 'vtcon1': device_unregister
[ 52.059076] PM: Removing info for No Bus:vtcon1
[ 52.059091] device: 'vtcon1': device_create_release
[ 52.059107] radeonfb 0000:00:10.0: BAR 0: can't reserve [mem
0x98000000-0x9fffffff pref]
[ 52.256151] aper_base: 98000000 MC_FB_LOC to: 9bff9800, MC_AGP_LOC
to: ffffa000
[ 52.256157] radeonfb (0000:00:10.0): Found 32768k of DDR 64 bits
wide videoram
I can confirm that offb_destroy is never called (not sure exactly
why), but in any case the call to radeon_kick_out_firmware_fb happen
much earlier, at least before the put_fb_info.
It is okay, put_fb_info() is called indirectly by radeon_kick_out_firmware_fb()
radeon_kick_out_firmware_fb()
remove_conflicting_framebuffers()
do_remove_conflicting_framebuffers()
do_unregister_framebuffer()
put_fb_info()
offb_destroy() is not called because there is an extra reference on old
fb_info (->count = 2):
static void put_fb_info(struct fb_info *fb_info)
{
if (!atomic_dec_and_test(&fb_info->count))
return;
if (fb_info->fbops->fb_destroy)
fb_info->fbops->fb_destroy(fb_info);
}
The question is why there is an extra reference, probably user-space
is still holding the fb_info reference obtained in fb_open() call and
fb_release() is never called. Besides not calling fbops->fb_destroy()
this also causes missing call of fbops->fb_release() (in fb_release())
which some fb drivers are implementing (but not offb.c).
Could you describe a bit more the chain of calls you were thinking of ?
Please add WARN_ON(1) to get_fb_info() and put_fb_info() so we can check
from the stacktrace if it is actually fb_open() that holds the extra
old fb_info reference.
drivers/video/fbdev/core/fbmem.c:
static struct fb_info *get_fb_info(unsigned int idx)
{
struct fb_info *fb_info;
if (idx >= FB_MAX)
return ERR_PTR(-ENODEV);
mutex_lock(®istration_lock);
fb_info = registered_fb[idx];
if (fb_info)
atomic_inc(&fb_info->count);
if (fb_info)
WARN_ON(1);
mutex_unlock(®istration_lock);
return fb_info;
}
static void put_fb_info(struct fb_info *fb_info)
{
WARN_ON(1);
if (!atomic_dec_and_test(&fb_info->count))
return;
if (fb_info->fbops->fb_destroy)
fb_info->fbops->fb_destroy(fb_info);
}
quoted
quoted
Signed-off-by: Mathieu Malaterre <redacted>
Link: https://bugs.debian.org/826629#57
Link: https://bugzilla.kernel.org/show_bug.cgi?id9741
Suggested-by: Lennart Sorensen <redacted>
---
v2: Only fails when CONFIG_PCC is not set
v3: Only fails when CONFIG_FB_OF is not set, CONFIG_PCC was too broad. Since the conflicts in region is due to OFfb explicitly refers to it.
It seems that there may still be configurations when this is
incorrect -> when offb drives primary (non-radeon) card and radeonfb
drives secondary (radeon) card..
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 4d77daeecf99..221879196531 100644
--- a/drivers/video/fbdev/aty/radeon_base.c
+++ b/drivers/video/fbdev/aty/radeon_base.c
@@ -2259,6 +2259,22 @@ static const 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)@@ -2312,19 +2328,27 @@ 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) {
+#ifndef CONFIG_FB_OF
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");
if (ret < 0) {
+#ifndef CONFIG_FB_OF
printk( KERN_ERR "radeonfb (%s): cannot request region 2.\n",
pci_name(rinfo->pdev));
goto err_release_pci0;
+#endif
}
/* map the regions */@@ -2509,10 +2533,12 @@ static int radeonfb_pci_register(struct pci_dev *pdev,
iounmap(rinfo->mmio_base);
err_release_pci2:
pci_release_region(pdev, 2);
+#ifndef CONFIG_FB_OF
err_release_pci0:
pci_release_region(pdev, 0);
err_release_fb:
framebuffer_release(info);
+#endif
err_disable:
err_out:
return ret;
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
Thanks,
-M
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics