linux-kernel - Re: [BUGFIX 0/9] Fix bug 59501 and code improvement for dock driver

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Date:	Fri, 14 Jun 2013 12:14:55 +0800
From:	"Jiang Liu (Gerry)" <jiang.liu@...wei.com>
To:	"Alexander E. Patrakov" <patrakov@...il.com>
CC:	Yinghai Lu <yinghai@...nel.org>,
	"Rafael J . Wysocki" <rjw@...k.pl>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Yijing Wang <wangyijing@...wei.com>,
	Jiang Liu <liuj97@...il.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUGFIX 0/9] Fix bug 59501 and code improvement for dock driver

On 2013/6/14 12:07, Alexander E. Patrakov wrote:
> 2013/6/14 Jiang Liu (Gerry) <jiang.liu@...wei.com>:
>> On 2013/6/14 10:30, Yinghai Lu wrote:
>>>
>>> On Thu, Jun 13, 2013 at 7:09 PM, Jiang Liu (Gerry) <jiang.liu@...wei.com>
>>> wrote:
>>>>
>>>> On 2013/6/14 2:42, Yinghai Lu wrote:
>>>>>
>>>>>
>>>>> On Thu, Jun 13, 2013 at 9:32 AM, Jiang Liu <jiang.liu@...wei.com> wrote:
>>>>>>
>>>>>>
>>>>>> Alexander E. Patrakov <patrakov@...il.com> reports two bugs related to
>>>>>> dock station support on Sony VAIO VPCZ23A4R. Actually there are at
>>>>>> least
>>>>>> four bugs related to Sony VAIO VPCZ23A4R dock support.
>>>>>> 1) can't correctly detect hotplug slot for dock state
>>>>>> 2) resource leak on undocking
>>>>>> 3) resource allocation failure for dock devices
>>>>>> 4) one bug in intel_snd_hda driver
>>>>>>
>>>>>> The first patch fixes issue 1, and the second patch fixes issue 2.
>>>>>> These two patches, if accepted, should be material for stable branches
>>>>>> too.
>>>>>> Patch 3-9 are code improvement for ACPI and dock driver.
>>>>>>
>>>>>> I have found the root cause for issue three, but still working on
>>>>>> solutions, and seems can't be solve in short time. So please help
>>>>>> to review and test patches for issue 1) and 2) first.
>>>>>
>>>>>
>>>>>
>>>>> the 3) is about pci resource allocation?
>>>>> because pcibios_add_bus is called too early?
>>>>>
>>>>> If that is case, we should have something like attached patch for it.
>>>>>
>>>>> With that, we will not need to worry about _OSC set for 3.10 etc.
>>>>>
>>>> Hi Yinghai,
>>>>      Seems not related to pcibios_add_bus(). According to my
>>>> investigation, the issue is caused by difference in PCI resource
>>>> assignment between boot time and runtime hotplug. On x86 platforms,
>>>> it respects PCI resource assignment from BIOS and only reassign
>>>> resources for unassigned BARs. But with acpiphp, it ignores BIOS
>>>> resource assignment and reassign all resources by OS.
>>>>      If we have enough resources, reassigning all PCI resources should
>>>> work too, but may fail if we are under resource constraints. On the
>>>> other handle, current PCI IOMM align algorithm may waste huge MMIO
>>>> address space if we have some PCI devices with huge IOMM BAR.
>>>>      On this Sony laptop, BIOS allocates limited IOMM resources for
>>>> the dock station and the dock station has a gfx which has a 256MB
>>>> IOMM BAR. So current acpiphp driver fails to allocate resources
>>>> for most devices on the dock station.
>>>
>>>
>>> Is it a regression?
>>
>> Not sure. But a little concern about check_hotplug_bridge(), it treats
>> dock station and devices on dock station with _EJD as hot-plug-gable
>> PCI bus and reserve extra resources for possible hot-adding. But I
>> think we should only reserve extra resource for dock station, and should
>> not reserve resource for devices on station with _EJD method.
>>
>>
>>>
>>>>       Currently I'm trying to change acpiphp to respect BIOS resource
>>>> assignment by calling pcibios_survey_resource_bus(), as in pci_root.c.
>>>> The other way is to change the IOMM resource allocation algorithm,
>>>> but obviously it's much more risky of regressions if changing the
>>>> algorithm.
>>>
>>>
>>> that is not going to help, need to increase bridge resource.
>>>
>>> please check if BIOS have setup option about hotplug MMIO pad size.
>>
>> For the first step, I'm trying to make hotplug case work in the same way as
>> boot time. Do you think this patch help?
>>
>> diff --git a/drivers/pci/hotplug/acpiphp_glue.c
>> b/drivers/pci/hotplug/acpiphp_gl
>> index 270fdba..12e3f6e 100644
>> --- a/drivers/pci/hotplug/acpiphp_glue.c
>> +++ b/drivers/pci/hotplug/acpiphp_glue.c
>> @@ -837,13 +837,13 @@ static int __ref enable_device(struct acpiphp_slot
>> *slot)
>>                                  max = pci_scan_bridge(bus, dev, max, pass);
>>                                  if (pass && dev->subordinate) {
>>                                          check_hotplug_bridge(slot, dev);
>> - pci_bus_size_bridges(dev->subordinate);
>> + pcibios_resource_survey_bus(dev->subordi
>>                                  }
>>                          }
>>                  }
>>          }
>>
>> -       pci_bus_assign_resources(bus);
>> +       pci_assign_unassigned_bus_resources(bus);
>>          acpiphp_sanitize_bus(bus);
>>          acpiphp_set_hpp_values(bus);
>>          acpiphp_set_acpi_region(slot);
>> ---
>
>
> The patch helped, thanks. Note: I have tested it together with
> pci_move_pcibios_add_bus_down.patch, I don't know yet if
> pci_move_pcibios_add_bus_down.patch is needed.
What's the situation now? Could you please send out dmesgs\ioports\iomem?
Thanks!

>
> --
> Alexander E. Patrakov
>
> .
>


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