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

[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/  |
>