Thanks for pointing it out.
Yeah that's right. The system will hang randomly a few minutes later,
because some certain actions in the graphical user session will trigger
the freeze.
I had a look at the function body of pci_read_config_dword:
#define PCI_OP_READ(size, type, len) \
int pci_bus_read_config_##size \
(struct pci_bus *bus, unsigned int devfn, int pos, type *value) \
{ \
int res; \
unsigned long flags; \
u32 data = 0; \
if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER; \
raw_spin_lock_irqsave(&pci_lock, flags); \
res = bus->ops->read(bus, devfn, pos, len, &data); \
*value = (type)data; \
raw_spin_unlock_irqrestore(&pci_lock, flags); \
return res; \
}
I guess, that bus->ops->read(...) might be the trigger.
Any hints how to continue debugging?
Cheers,
Roland
Am 30.08.2016 um 01:54 schrieb Bjorn Helgaas:
> On Mon, Aug 29, 2016 at 09:55:56PM +0200, Roland Singer wrote:
>> Just tried it and the system didn't freeze. However it will freeze
>> after some time (few minutes while working).
>>
>> Seams to be pci_read_config_dword. Where is this exactly defined?
>
> pci_read_config_dword() is defined in include/linux/pci.h. It calls
> pci_bus_read_config_dword() which is defined by the PCI_OP_READ() macro
> in drivers/pci/access.c.
>
> If I understand correctly, this:
>
> dis_dev_get();
> pci_read_config_dword(dis_dev, 0, &cfg_word);
> dis_dev_put();
>
> causes an immediate system hang, but if you only do this:
>
> dis_dev_get();
> dis_dev_put();
>
> the system hangs a few minutes later. Right?
>
>> Am 29.08.2016 um 21:07 schrieb Bjorn Helgaas:
>>> On Mon, Aug 29, 2016 at 08:46:17PM +0200, Roland Singer wrote:
>>>> Hi Bjorn,
>>>>
>>>> I am using the bbswitch kernel module to switch off/on the GPU and
>>>> to obtain the GPU power state.
>>>> Obtaining the GPU state immediately after starting the graphical user
>>>> session freezes the system.
>>>>
>>>> This code triggers something, which is responsible for the freeze.
>>>>
>>>> ---
>>>> // Returns 1 if the card is disabled, 0 if enabled
>>>> static int is_card_disabled(void) {
>>>> u32 cfg_word;
>>>> // read first config word which contains Vendor and Device ID. If all bits
>>>> // are enabled, the device is assumed to be off
>>>> pci_read_config_dword(dis_dev, 0, &cfg_word);
>>>> // if one of the bits is not enabled (the card is enabled), the inverted
>>>> // result will be non-zero and hence logical not will make it 0 ("false")
>>>> return !~cfg_word;
>>>> }
>>>>
>>>> static int bbswitch_proc_show(struct seq_file *seqfp, void *p) {
>>>> // show the card state. Example output: 0000:01:00:00 ON
>>>> dis_dev_get();
>>>> seq_printf(seqfp, "%s %s\n", dev_name(&dis_dev->dev),
>>>> is_card_disabled() ? "OFF" : "ON");
>>>> dis_dev_put();
>>>> return 0;
>>>> }
>>>> ---
>>>>
>>>> Either dis_dev_get or pci_read_config_dword is the trigger.
>>>
>>> What happens if you remove the call to is_card_disabled()? Does the
>>> system still freeze if you only do the dis_dev_get()/dis_dev_put()?
>>>
>>>> Link to the bbswitch module source code:
>>>> https://github.com/Bumblebee-Project/bbswitch/blob/master/bbswitch.c#L333
>>>>
>>>>
>>>> Am 29.08.2016 um 18:02 schrieb Bjorn Helgaas:
>>>>> [+cc linux-acpi, linux-kernel, dri-devel]
>>>>>
>>>>> Hi Roland,
>>>>>
>>>>> I have no idea how to debug this problem. Are you seeing something
>>>>> that suggests it may be a PCI problem?
>>>>>
>>>>> On Tue, Aug 23, 2016 at 11:23:45AM +0200, Roland Singer wrote:
>>>>>> Hi,
>>>>>>
>>>>>> hope somebody can help me fix this kernel problem which affects the following machines:
>>>>>>
>>>>>> - Clevo P651RA (i7-6700HQ/GTX 965M, part of the P6xxRx family which are also affected)
>>>>>> - MSI GE62 Apache Pro (i7-6700HQ/GTX 960M)
>>>>>> - Gigabyte P35V5 (i7-6700HQ/GTX 970M)
>>>>>> - Razer Blade 14" (2016) (i7-6700HQ/GTX 970M) (BIOS 5.11, 04/07/2016)
>>>>>>
>>>>>>
>>>>>> The kernel freezes if the graphical user session (Xorg & Wayland) is
>>>>>> started with a switched off discrete GPU card (NVIDIA).
>>>>>> If the discrete GPU is switched off after the graphical session start,
>>>>>> then everything works as expected, until the graphical session is restarted.
>>>>>>
>>>>>> This problem seams to be linked to specific BIOS settings. If the computer
>>>>>> is started with the following command line:
>>>>>>
>>>>>> acpi_osi=! acpi_osi="Windows 2009"
>>>>>>
>>>>>> then the kernel freeze does not occur anymore. However this required a special
>>>>>> ACPI DSDT firmware patch for the Razer Blade 2016 laptop:
>>>>>>
>>>>>> https://github.com/m4ng0squ4sh/razer_blade_14_2016_acpi_dsdt
>>>>>>
>>>>>> I strongly recommend to fix this in the kernel and I am ready to help and solve
>>>>>> this problem with some help.
>>>>>>
>>>>>> Here is a link to the GitHub issue with further information:
>>>>>>
>>>>>> https://github.com/Bumblebee-Project/Bumblebee/issues/764#issuecomment-241212595
>>>>>>
>>>>>> Here are some more detailed information:
>>>>>>
>>>>>> https://github.com/Lekensteyn/acpi-stuff/blob/master/Clevo-P651RA/notes.txt
>>>>>>
>>>>>> Hope somebody can help.
>>>>
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