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

Hi Bj?rn,

On Tue, Sep 30, 2014 at 7:12 AM, Bj?rn Erik Nilsen [off-list ref] wrote:

Hi Fabio,

On Wed, 2014-08-06 at 21:39 -0300, an unknown sender wrote:

quoted

From: Fabio Estevam <redacted>

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 <redacted>
Signed-off-by: Fabio Estevam <redacted>

Tested-by: Bj?rn Erik Nilsen <redacted>

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.