[PATCH] ARM: mx6: Fix suspend/resume with PCI

[Fabio Estevam]

Hi Bjørn,

On Tue, Sep 30, 2014 at 7:12 AM, Bjørn Erik Nilsen <ben at datarespons.no> wrote:
> Hi Fabio,
>
> On Wed, 2014-08-06 at 21:39 -0300, an unknown sender wrote:
>> From: Fabio Estevam <fabio.estevam at freescale.com>
>>
>> When PCI is used and a suspend/resume sequence is done we see the following
>> kernel hang:
>>
>> root at freescale /$ echo mem > /sys/power/state
>> [   16.099018] PM: Syncing filesystems ... done.
>> [   16.141010] Freezing user space processes ... (elapsed 0.002 seconds) done.
>> [   16.150840] Freezing remaining freezable tasks ... (elapsed 0.003 seconds) done.
>> [   16.199438] random: nonblocking pool is initialized
>> [   16.229639] PM: suspend of devices complete after 64.793 msecs
>> [   16.235488] PM: suspend devices took 0.070 seconds
>> [   16.245301] PM: late suspend of devices complete after 4.968 msecs
>> [   16.257063] PM: noirq suspend of devices complete after 5.538 msecs
>> [   16.263425] Disabling non-boot CPUs ...
>> [   16.274666] CPU1: shutdown
>> [   16.286351] CPU2: shutdown
>> [   16.294169] CPU3: shutdown
>> [   16.299551] Enabling non-boot CPUs ...
>> [   16.304155] CPU1: Booted secondary processor
>> [   16.305717] CPU1 is up
>> [   16.313078] CPU2: Booted secondary processor
>> [   16.313456] CPU2 is up
>> [   16.320778] CPU3: Booted secondary processor
>> [   16.321174] CPU3 is up
>>       (hangs here)
>>
>> Implement a workaround for the erratum ERR005723: "PCIe does not support L2
>> Power Down", which consists in toggling bit 18 (TEST_POWERDOWN) of GPR1 register.
>>
>> Tested on a mx6qsabresd TO1.2 revC2.
>>
>> Reported-by: Shawn Guo <shawn.guo at freescale.com>
>> Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
>
> Tested-by: Bjørn Erik Nilsen <ben at datarespons.no>
>
> I encountered exactly the same problem and can confirm your patch works.
>
> Thank you!
>
> I hope this patch (or one that is considered a proper solution) will
> make it to the mainline kernel any time soon.

Thanks for testing.

This is a workaround found on FSL kernel. We still need to come up
with a proper fix for this PCI suspend/resume issue.