Re: [PATCH] bus: mhi: pci-generic: Fix hibernation

[Manivannan Sadhasivam <mani@kernel.org>]

On Tue, Jun 01, 2021 at 08:17:25PM +0200, Loic Poulain wrote:
> This patch fixes crash after resuming from hibernation. The issue
> occurs when mhi stack is builtin and so part of the 'restore-kernel',
> causing the device to be resumed from 'restored kernel' with a no
> more valid context (memory mappings etc...) and leading to spurious
> crashes.
> 
> This patch fixes the issue by implementing proper freeze/restore
> callbacks.
> 
> Reported-by: Shujun Wang <wsj20369@163.com>
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

Applied to mhi-fixes!

Thanks,
Mani

> ---
>  drivers/bus/mhi/pci_generic.c | 36 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
> index aa8f8d5..afa8763 100644
> --- a/drivers/bus/mhi/pci_generic.c
> +++ b/drivers/bus/mhi/pci_generic.c
> @@ -888,9 +888,43 @@ static int __maybe_unused mhi_pci_resume(struct device *dev)
>  	return ret;
>  }
>  
> +static int __maybe_unused mhi_pci_freeze(struct device *dev)
> +{
> +	struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
> +	struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
> +
> +	/* We want to stop all operations, hibernation does not guarantee that
> +	 * device will be in the same state as before freezing, especially if
> +	 * the intermediate restore kernel reinitializes MHI device with new
> +	 * context.
> +	 */
> +	if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
> +		mhi_power_down(mhi_cntrl, false);
> +		mhi_unprepare_after_power_down(mhi_cntrl);
> +	}
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused mhi_pci_restore(struct device *dev)
> +{
> +	struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
> +
> +	/* Reinitialize the device */
> +	queue_work(system_long_wq, &mhi_pdev->recovery_work);
> +
> +	return 0;
> +}
> +
>  static const struct dev_pm_ops mhi_pci_pm_ops = {
>  	SET_RUNTIME_PM_OPS(mhi_pci_runtime_suspend, mhi_pci_runtime_resume, NULL)
> -	SET_SYSTEM_SLEEP_PM_OPS(mhi_pci_suspend, mhi_pci_resume)
> +#ifdef CONFIG_PM_SLEEP
> +	.suspend = mhi_pci_suspend,
> +	.resume = mhi_pci_resume,
> +	.freeze = mhi_pci_freeze,
> +	.thaw = mhi_pci_restore,
> +	.restore = mhi_pci_restore,
> +#endif
>  };
>  
>  static struct pci_driver mhi_pci_driver = {
> -- 
> 2.7.4
>