Re: [PATCH v6 07/10] mhi: pci_generic: Add PCI error handlers

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Tue, Dec 29, 2020 at 09:43:48AM +0100, Loic Poulain wrote:
> In AER capable root complex, errors are reported to the host which
> can then act accordingly and perform PCI recovering procedure.
> 
> This patch enables error reporting and implements error_detected,
> slot_reset and resume callbacks.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> Reviewed-by Hemant Kumar <hemantk@codeaurora.org>
> ---
>  drivers/bus/mhi/pci_generic.c | 50 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
> index 3297d95..9fe1e30 100644
> --- a/drivers/bus/mhi/pci_generic.c
> +++ b/drivers/bus/mhi/pci_generic.c
> @@ -8,6 +8,7 @@
>   * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
>   */
>  
> +#include <linux/aer.h>
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/mhi.h>
> @@ -405,6 +406,8 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	pci_save_state(pdev);
>  	mhi_pdev->pci_state = pci_store_saved_state(pdev);
>  
> +	pci_enable_pcie_error_reporting(pdev);
> +
>  	err = mhi_register_controller(mhi_cntrl, mhi_cntrl_config);
>  	if (err)
>  		return err;
> @@ -501,7 +504,54 @@ static void mhi_pci_reset_done(struct pci_dev *pdev)
>  	set_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status);
>  }
>  
> +static pci_ers_result_t mhi_pci_error_detected(struct pci_dev *pdev,
> +					       pci_channel_state_t state)
> +{
> +	struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
> +	struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
> +
> +	dev_err(&pdev->dev, "PCI error detected, state = %u\n", state);
> +
> +	if (state == pci_channel_io_perm_failure)
> +		return PCI_ERS_RESULT_DISCONNECT;
> +
> +	/* 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);
> +	} else {
> +		/* Nothing to do */
> +		return PCI_ERS_RESULT_RECOVERED;
> +	}
> +
> +	pci_disable_device(pdev);
> +
> +	return PCI_ERS_RESULT_NEED_RESET;
> +}
> +
> +static pci_ers_result_t mhi_pci_slot_reset(struct pci_dev *pdev)
> +{
> +	if (pci_enable_device(pdev)) {
> +		dev_err(&pdev->dev, "Cannot re-enable PCI device after reset.\n");
> +		return PCI_ERS_RESULT_DISCONNECT;
> +	}
> +

This callback will be called after PCI slot reset, so we should also be resetting
the device after enabling it.

Thanks,
Mani

> +	return PCI_ERS_RESULT_RECOVERED;
> +}
> +
> +static void mhi_pci_io_resume(struct pci_dev *pdev)
> +{
> +	struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
> +
> +	dev_err(&pdev->dev, "PCI slot reset done\n");
> +
> +	queue_work(system_long_wq, &mhi_pdev->recovery_work);
> +}
> +
>  static const struct pci_error_handlers mhi_pci_err_handler = {
> +	.error_detected = mhi_pci_error_detected,
> +	.slot_reset = mhi_pci_slot_reset,
> +	.resume = mhi_pci_io_resume,
>  	.reset_prepare = mhi_pci_reset_prepare,
>  	.reset_done = mhi_pci_reset_done,
>  };
> -- 
> 2.7.4
>