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SubjectRE: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed
Date
Hi,
Can you elaborate how this can even happen?
Isn't the interrupt aggregation capability should attend for those cases?

Thanks,
Avri

> -----Original Message-----
> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> owner@vger.kernel.org] On Behalf Of Asutosh Das
> Sent: Tuesday, January 30, 2018 6:54 AM
> To: subhashj@codeaurora.org; cang@codeaurora.org;
> vivek.gautam@codeaurora.org; rnayak@codeaurora.org;
> vinholikatti@gmail.com; jejb@linux.vnet.ibm.com;
> martin.petersen@oracle.com
> Cc: linux-scsi@vger.kernel.org; Venkat Gopalakrishnan
> <venkatg@codeaurora.org>; Asutosh Das <asutoshd@codeaurora.org>; open
> list <linux-kernel@vger.kernel.org>
> Subject: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed
>
> From: Venkat Gopalakrishnan <venkatg@codeaurora.org>
>
> As multiple requests are submitted to the ufs host controller in parallel there
> could be instances where the command completion interrupt arrives later for a
> request that is already processed earlier as the corresponding doorbell was
> cleared when handling the previous interrupt. Read the interrupt status in a
> loop after processing the received interrupt to catch such interrupts and handle
> it.
>
> Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
> ---
> drivers/scsi/ufs/ufshcd.c | 27 +++++++++++++++++++--------
> 1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index
> 8af2af3..58d81de 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -5357,19 +5357,30 @@ static irqreturn_t ufshcd_intr(int irq, void *__hba)
> u32 intr_status, enabled_intr_status;
> irqreturn_t retval = IRQ_NONE;
> struct ufs_hba *hba = __hba;
> + int retries = hba->nutrs;
>
> spin_lock(hba->host->host_lock);
> intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
> - enabled_intr_status =
> - intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
>
> - if (intr_status)
> - ufshcd_writel(hba, intr_status, REG_INTERRUPT_STATUS);
> + /*
> + * There could be max of hba->nutrs reqs in flight and in worst case
> + * if the reqs get finished 1 by 1 after the interrupt status is
> + * read, make sure we handle them by checking the interrupt status
> + * again in a loop until we process all of the reqs before returning.
> + */
> + do {
> + enabled_intr_status =
> + intr_status & ufshcd_readl(hba,
> REG_INTERRUPT_ENABLE);
> + if (intr_status)
> + ufshcd_writel(hba, intr_status,
> REG_INTERRUPT_STATUS);
> + if (enabled_intr_status) {
> + ufshcd_sl_intr(hba, enabled_intr_status);
> + retval = IRQ_HANDLED;
> + }
> +
> + intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
> + } while (intr_status && --retries);
>
> - if (enabled_intr_status) {
> - ufshcd_sl_intr(hba, enabled_intr_status);
> - retval = IRQ_HANDLED;
> - }
> spin_unlock(hba->host->host_lock);
> return retval;
> }
> --
> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
> Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> Foundation Collaborative Project.

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