On Mon, Dec 14, 2020 at 03:25:33PM +0100, Loic Poulain wrote:
> Add support for system wide suspend/resume. During suspend, MHI
> device controller must be put in M3 state and PCI bus in D3 state.
>
> Add a recovery procedure allowing to reinitialize the device in case
> of error during resume steps, which can happen if device loses power
> (and so its context) while system suspend.
>
> Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
> Reviewed-by Hemant Kumar <hemantk@xxxxxxxxxxxxxx>
> ---
> drivers/bus/mhi/pci_generic.c | 102 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 102 insertions(+)
>
> diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
> index 2521cd4..0936701 100644
> --- a/drivers/bus/mhi/pci_generic.c
> +++ b/drivers/bus/mhi/pci_generic.c
> @@ -13,6 +13,7 @@
> #include <linux/mhi.h>
> #include <linux/module.h>
> #include <linux/pci.h>
> +#include <linux/workqueue.h>
>
> #define MHI_PCI_DEFAULT_BAR_NUM 0
>
> @@ -186,6 +187,7 @@ enum mhi_pci_device_status {
> struct mhi_pci_device {
> struct mhi_controller mhi_cntrl;
> struct pci_saved_state *pci_state;
> + struct work_struct recovery_work;
> unsigned long status;
> };
>
> @@ -313,6 +315,48 @@ static void mhi_pci_runtime_put(struct mhi_controller *mhi_cntrl)
> /* no PM for now */
> }
>
> +static void mhi_pci_recovery_work(struct work_struct *work)
> +{
> + struct mhi_pci_device *mhi_pdev = container_of(work, struct mhi_pci_device,
> + recovery_work);
> + struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
> + struct pci_dev *pdev = to_pci_dev(mhi_cntrl->cntrl_dev);
> + int err;
> +
> + dev_warn(&pdev->dev, "device recovery started\n");
> +
> + /* Clean up MHI state */
> + 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);
> + }
> +
> + /* Check if we can recover without full reset */
> + pci_set_power_state(pdev, PCI_D0);
> + pci_load_saved_state(pdev, mhi_pdev->pci_state);
> + pci_restore_state(pdev);
These pci state settings seems redundant with resume().
In this function you should first check if MHI is alive, if yes then do
power up. Else you should just exit.
> +
> + if (!mhi_pci_is_alive(mhi_cntrl))
> + goto err_try_reset;
> +
> + err = mhi_prepare_for_power_up(mhi_cntrl);
> + if (err)
> + goto err_try_reset;
> +
> + err = mhi_sync_power_up(mhi_cntrl);
> + if (err)
> + goto err_unprepare;
Add a debug log for recovery success.
> +
> + set_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status);
> + return;
> +
> +err_unprepare:
> + mhi_unprepare_after_power_down(mhi_cntrl);
> +err_try_reset:
> + if (pci_reset_function(pdev))
So if the device recovers, who will make sure reinitializing the MHI
controller? That's why I think we should convey the recovery result to
PM core. I don't think using workqueue here is a good idea.
> + dev_err(&pdev->dev, "Recovery failed\n");
> +}
> +
> static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> {
> const struct mhi_pci_dev_info *info = (struct mhi_pci_dev_info *) id->driver_data;
> @@ -327,6 +371,8 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> if (!mhi_pdev)
> return -ENOMEM;
>
> + INIT_WORK(&mhi_pdev->recovery_work, mhi_pci_recovery_work);
> +
> mhi_cntrl_config = info->config;
> mhi_cntrl = &mhi_pdev->mhi_cntrl;
>
> @@ -391,6 +437,8 @@ static void mhi_pci_remove(struct pci_dev *pdev)
> struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
> struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
>
> + cancel_work_sync(&mhi_pdev->recovery_work);
> +
> if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
> mhi_power_down(mhi_cntrl, true);
> mhi_unprepare_after_power_down(mhi_cntrl);
> @@ -456,12 +504,66 @@ static const struct pci_error_handlers mhi_pci_err_handler = {
> .reset_done = mhi_pci_reset_done,
> };
>
> +static int __maybe_unused mhi_pci_suspend(struct device *dev)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> + struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
> + struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
> +
> + cancel_work_sync(&mhi_pdev->recovery_work);
> +
> + /* Transition to M3 state */
> + mhi_pm_suspend(mhi_cntrl);
> +
> + pci_save_state(pdev);
> + pci_disable_device(pdev);
> + pci_wake_from_d3(pdev, true);
> + pci_set_power_state(pdev, PCI_D3hot);
> +
> + return 0;
> +}
> +
> +static int __maybe_unused mhi_pci_resume(struct device *dev)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> + struct mhi_pci_device *mhi_pdev = dev_get_drvdata(dev);
> + struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
> + int err;
> +
> + pci_set_power_state(pdev, PCI_D0);
> + pci_restore_state(pdev);
> + pci_set_master(pdev);
> +
> + err = pci_enable_device(pdev);
> + if (err)
> + goto err_recovery;
> +
> + /* Exit M3, transition to M0 state */
> + err = mhi_pm_resume(mhi_cntrl);
> + if (err) {
> + dev_err(&pdev->dev, "failed to resume device: %d\n", err);
> + goto err_recovery;
> + }
> +
> + return 0;
> +
> +err_recovery:
> + /* The device may have loose power or crashed, try recovering it */
Did you actually hit this scenario? In the case of power loss or crash, can we
access the MHI register space?
Thanks,
Mani
> + queue_work(system_long_wq, &mhi_pdev->recovery_work);
> + return 0;
> +}
> +
> +static const struct dev_pm_ops mhi_pci_pm_ops = {
> + SET_SYSTEM_SLEEP_PM_OPS(mhi_pci_suspend, mhi_pci_resume)
> +};
> +
> static struct pci_driver mhi_pci_driver = {
> .name = "mhi-pci-generic",
> .id_table = mhi_pci_id_table,
> .probe = mhi_pci_probe,
> .remove = mhi_pci_remove,
> .err_handler = &mhi_pci_err_handler,
> + .driver.pm = &mhi_pci_pm_ops
> };
> module_pci_driver(mhi_pci_driver);
>
> --
> 2.7.4
>
