The imx6q suspend/resume is broken on 3.16-rc due to PCIe

[Lucas Stach]

Hi Shawn,

Over the weekend I tried to reproduce your problem on a SabreSD board,
but wasn't able to trigger the issue. 3.16-rc3 with PCIe active works
just fine over a suspend and resume cycle for me.

One possibly relevant difference is that I've booted with NFSroot, while
it seems you are using a SATA connected device. Is this right? If so,
can you test if it works if you boot from SDcard or the like? This might
be relevant as PCIe and SATA share some clocks.

Regards,
Lucas

Am Dienstag, den 01.07.2014, 14:51 +0800 schrieb Shawn Guo:
> On Mon, Jun 30, 2014 at 03:44:24PM +0200, Lucas Stach wrote:
> > Hi Shawn,
> > 
> > can you please test the attached patch on top of 3.16-rc* to see if it
> > helps? If it works for you I would like to try and get this into 3.16 as
> > a bugfix.
> 
> Unfortunately, it doesn't work.  With your change, now it hangs in
> suspend procedure.
> 
> $ echo mem > /sys/power/state
> PM: Syncing filesystems ... done.
> PM: Preparing system for mem sleep
> Freezing user space processes ... (elapsed 0.005 seconds) done.
> Freezing remaining freezable tasks ... (elapsed 0.003 seconds) done.
> PM: Entering mem sleep
> sd 0:0:0:0: [sda] Synchronizing SCSI cache
> sd 0:0:0:0: [sda] Stopping disk
> PM: suspend of devices complete after 102.992 msecs
> PM: suspend devices took 0.110 seconds
> PM: late suspend of devices complete after 12.808 msecs
> 
> Shawn
> 
> > 
> > Regards,
> > Lucas
> > 
> > --------------------------->8-----------------------------
> > From f3bfdc9c19249188fa153b1568c3129cd31af4f5 Mon Sep 17 00:00:00 2001
> > From: Lucas Stach <l.stach at pengutronix.de>
> > Date: Mon, 30 Jun 2014 15:33:04 +0200
> > Subject: [PATCH] PCI: imx6: add workaround for errata ERR005723
> > 
> > Fixes system hang after resume from suspend to mem.
> > 
> > Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> > ---
> >  drivers/pci/host/pci-imx6.c | 33 +++++++++++++++++++++++++++++++++
> >  1 file changed, 33 insertions(+)
> > 
> > diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> > index a568efaa331c..5c58a3ee5dbf 100644
> > --- a/drivers/pci/host/pci-imx6.c
> > +++ b/drivers/pci/host/pci-imx6.c
> > @@ -589,6 +589,38 @@ static int __init imx6_pcie_probe(struct platform_device *pdev)
> >  	return 0;
> >  }
> >  
> > +#ifdef CONFIG_PM_SLEEP
> > +static int imx6_pcie_suspend(struct device *dev)
> > +{
> > +	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> > +
> > +	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
> > +			IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18);
> > +
> > +	return 0;
> > +}
> > +
> > +static int imx6_pcie_resume(struct device *dev)
> > +{
> > +	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
> > +
> > +	/*
> > +	 * This is a workaround for
> > +	 * ERR005723: PCIe does not support L2 power down
> > +	 * Toggling the PHY PD bit around system L2 state switching seems to be
> > +	 * enough to wake the PCIe logic after a power down.
> > +	 */
> > +	regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
> > +			IMX6Q_GPR1_PCIE_TEST_PD, 0 << 18);
> > +
> > +	return 0;
> > +}
> > +#endif
> > +
> > +static SIMPLE_DEV_PM_OPS(imx6_pcie_pm_ops,
> > +		imx6_pcie_suspend,
> > +		imx6_pcie_resume);
> > +
> >  static const struct of_device_id imx6_pcie_of_match[] = {
> >  	{ .compatible = "fsl,imx6q-pcie", },
> >  	{},
> > @@ -600,6 +632,7 @@ static struct platform_driver imx6_pcie_driver = {
> >  		.name	= "imx6q-pcie",
> >  		.owner	= THIS_MODULE,
> >  		.of_match_table = imx6_pcie_of_match,
> > +		.pm = &imx6_pcie_pm_ops,
> >  	},
> >  };
> >  
> > -- 
> > 2.0.0
> > 
> > 
> > -- 
> > Pengutronix e.K.             | Lucas Stach                 |
> > Industrial Linux Solutions   | http://www.pengutronix.de/  |
> > 
> 
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-- 
Pengutronix e.K.             | Lucas Stach                 |
Industrial Linux Solutions   | http://www.pengutronix.de/  |