Date:   Mon, 29 Aug 2016 21:55:56 +0200
From:   Roland Singer <roland.singer@...ertbit.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: Kernel Freeze with American Megatrends BIOS

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?


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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