linux-kernel - Re: [PATCH] PCI: Do not enable async suspend for JMicron chips

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Date:	Wed, 5 Nov 2014 12:03:43 -0700
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Barto <mister.freeman@...oste.net>
Cc:	Chuansheng Liu <chuansheng.liu@...el.com>,
	Aaron Lu <aaron.lu@...el.com>, Tejun Heo <tj@...nel.org>,
	Rafael Wysocki <rjw@...ysocki.net>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: Do not enable async suspend for JMicron chips

On Wed, Nov 5, 2014 at 11:46 AM, Barto <mister.freeman@...oste.net> wrote:
> this patch solves these 2 bug reports :
>
> https://bugzilla.kernel.org/show_bug.cgi?id=84861
>
> https://bugzilla.kernel.org/show_bug.cgi?id=81551

Those bugs were already mentioned.  But e6b7e41cdd8c claims to solve
https://bugzilla.kernel.org/show_bug.cgi?id=81551, and 84861 is a
duplicate of 81551, so it should also be fixed by e6b7e41cdd8c.

So the question is, why was e6b7e41cdd8c insufficient?  Presumably it
was tested and somebody thought it did fix the problem.

> in simple words : JMicron IDE/Sata controlers family ( JMBxxx ) are not
> fully compatible with async_suspend feature, when a user tries to put
> his PC on standby mode then at wake-up JMicron IDE/Sata controlers will
> not work, because of a brother-relation between the SATA and IDE part on
> this JMicron PCI card
>
>
>
>
> Le 05/11/2014 19:01, Bjorn Helgaas a écrit :
>> On Tue, Nov 4, 2014 at 6:31 PM, Chuansheng Liu <chuansheng.liu@...el.com> wrote:
>>> The JMicron chip 361/363/368 contains one SATA controller and
>>> one PATA controller, they are brother-relation ship in PCI tree,
>>> but for powering on these both controller, we must follow the
>>> sequence one by one, otherwise one of them can not be powered on
>>> successfully.
>>
>> This should mention what's broken and what problem a user would see.
>> This changelog sounds a lot like the one for e6b7e41cdd8c, so I don't
>> know if this is for a new, related problem, or what.
>>
>>> So here we disable the async suspend method for Jmicron chip.
>>>
>>> Bug link:
>>> https://bugzilla.kernel.org/show_bug.cgi?id=81551
>>> https://bugzilla.kernel.org/show_bug.cgi?id=84861
>>>
>>> And we can revert the below commit after this patch is applied:
>>> e6b7e41(ata: Disabling the async PM for JMicron chip 363/361)
>>>
>>> Cc: stable@...r.kernel.org # 3.15+
>>> Acked-by: Aaron Lu <aaron.lu@...el.com>
>>> Signed-off-by: Chuansheng Liu <chuansheng.liu@...el.com>
>>> ---
>>>  drivers/pci/pci.c |   12 +++++++++++-
>>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>>> index 625a4ac..53128f0 100644
>>> --- a/drivers/pci/pci.c
>>> +++ b/drivers/pci/pci.c
>>> @@ -2046,7 +2046,17 @@ void pci_pm_init(struct pci_dev *dev)
>>>         pm_runtime_forbid(&dev->dev);
>>>         pm_runtime_set_active(&dev->dev);
>>>         pm_runtime_enable(&dev->dev);
>>> -       device_enable_async_suspend(&dev->dev);
>>> +
>>> +       /*
>>> +        * The JMicron chip 361/363/368 contains one SATA controller and
>>> +        * one PATA controller, they are brother-relation ship in PCI tree,
>>> +        * but for powering on these both controller, we must follow the
>>> +        * sequence one by one, otherwise one of them can not be powered on
>>> +        * successfully, so here we disable the async suspend method for
>>> +        * Jmicron chip.
>>> +        */
>>> +       if (dev->vendor != PCI_VENDOR_ID_JMICRON)
>>> +               device_enable_async_suspend(&dev->dev);
>>
>> I don't like littering the core PCI code with vendor tests like this.
>> This would be the only one, except for an ancient DECchip 21050 bridge
>> erratum.
>>
>> And why would we want a test for *all* JMicron devices here, when you
>> claim the problem only affects a few specific ones?
>>
>> And what's the story with the e6b7e41cdd8c ("ata: Disabling the async
>> PM for JMicron chip 363/361") connection?  Is something broken even
>> with e6b7e41cdd8c, and this is a better fix?  Or is this simply a
>> different way of fixing the same problem?
>>
>>>         dev->wakeup_prepared = false;
>>>
>>>         dev->pm_cap = 0;
>>> --
>>> 1.7.9.5
>>>
>>
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