[+cc Alex, Christian, dri-devel]
On Sat, Oct 11, 2014 at 1:37 PM, Shawn Starr shawn.starr@rogers.com wrote:
On September 11, 2014 04:26:21 PM Bjorn Helgaas wrote:
[+cc linux-pci]
On Sat, Aug 2, 2014 at 10:02 AM, Shawn Starr shawn.starr@rogers.com wrote:
Hello devs,
There are two issues I am encountering with the PCIe Hotplug driver on my Lenovo Laptop (W500). I note this goes back further than 3.15.
It is noted here: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id= f244d8b623dae7a7bc695b0336f67729b95a9736 https://bugzilla.kernel.org/show_bug.cgi?id=79701
And my open bug here: https://bugzilla.kernel.org/show_bug.cgi?id=77261
- If I enable the device to use both the integrated and discrete GPU,
pciehp will decide to force unload radeon because it puts itself into a power saving state, fails back to the Intel integrated GPU in this case unless I tell radeon.ko to runpm=0 (no power management, then pciehp wont touch it).
- If the Radeon GPU resets and you use pci_reset=1 for kernel module
option, pciehp decides to force unload radeon even though the GPU is trying to setup after failing.
Kernel I am using right now: 3.16.0-0.rc7.git3.1.fc21.x86_64 (about to boot into snapshot kernel-core-3.16.0-0.rc7.git4.1.fc21.x86_64)
Hi Shawn,
Thanks for the report and sorry that it got dropped. But I see you're cc'd on https://bugzilla.kernel.org/show_bug.cgi?id=79701, so you've probably seen the work there. If you can try out the patches I just posted, that would be great.
Bjorn
Hi Bjorn,
For #1) This is fixed in linux-next (tracking 3.18.0-0.rc0.git1.2.fc22.1.x86_64 nondebug kernel for Fedora). PCIe HotPlug no longer unloads radeon. For this bugzilla report we can close it.
#2) This still has weird results however, radeon.hard_reset=1 is experimental and while it attempts to reset GPU, PCIe HotPlug seems to interact in this.
This can be tested by adding to grub command line radeon.hard_reset=1. When X has started up, trigger a reset by cat /sys/kernel/debug/dri/#/radeon_gpu_reset. It will output 0, cat it again will show 1.
Attempt to drag a window. The this will trigger a GPU reset, but fail to recover, its unknown if PCIe HotPlug is preventing a proper reset or not but there is pciehp calls in the stack trace.
A PCIe device reset usually looks like a hotplug event because the PCIe link goes down and comes back up. As far as the PCI core is concerned, it can't tell the difference between (1) a simple reset where the link bounces and (2) removal of one device followed by addition of another.
b440bde74f04 ("PCI: Add pci_ignore_hotplug() to ignore hotplug events for a device") addressed this for some similar cases, but it looks like we probably need some more calls to pci_ignore_hotplug() in the radeon driver reset methods.
Can you please open a bugzilla and attach the complete dmesg log, including the GPU reset and recovery failure?
Bjorn