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Date: Tue, 27 Aug 2013 13:50:37 +0530
From: Subhash Jadavani <subhashj@...eaurora.org>
To: Dolev Raviv <draviv@...eaurora.org>
CC: linux-scsi@...r.kernel.org, linux-arm-msm@...r.kernel.org,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] scsi: ufs: read door bell register after clearing interrupt
aggregation
Looks good to me.
Reviewed-by: Subhash Jadavani <subhashj@...eaurora.org>
On 8/25/2013 4:06 PM, Dolev Raviv wrote:
> In interrupt context, after reading and comparing the UTRLDBR to
> hba->outstanding_request and before resetting the interrupt aggregation,
> there might be completion of another transfer request (TR). Such TRs might
> get stuck, pending, until the next interrupt is generated.
>
> The fix reads the UTRLDBR after resetting the interrupt aggregation and
> handles completed TRs.
>
> Signed-off-by: Dolev Raviv <draviv@...eaurora.org>
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 4dca9b4..30c84d8 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1915,6 +1915,13 @@ static void ufshcd_uic_cmd_compl(struct ufs_hba *hba)
> /**
> * ufshcd_transfer_req_compl - handle SCSI and query command completion
> * @hba: per adapter instance
> + *
> + * Resetting interrupt aggregation counters first and reading the DOOR_BELL
> + * afterward , allows us to handle all the completed requests.
> + * In order to prevent other interrupts starvation the DB is read once
> + * after reset. The down side of this solution is the possibility of false
> + * interrupt if device completes another request after resetting aggregation
> + * and before reading the DB.
> */
> static void ufshcd_transfer_req_compl(struct ufs_hba *hba)
> {
> @@ -1924,47 +1931,36 @@ static void ufshcd_transfer_req_compl(struct ufs_hba *hba)
> u32 tr_doorbell;
> int result;
> int index;
> - bool int_aggr_reset = false;
> +
> + /* Reset interrupt aggregation counters */
> + ufshcd_config_int_aggr(hba, INT_AGGR_RESET);
>
> tr_doorbell = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
> completed_reqs = tr_doorbell ^ hba->outstanding_reqs;
>
> - for (index = 0; index < hba->nutrs; index++) {
> - if (test_bit(index, &completed_reqs)) {
> - lrbp = &hba->lrb[index];
> - cmd = lrbp->cmd;
> - /*
> - * Don't skip resetting interrupt aggregation counters
> - * if a regular command is present.
> - */
> - int_aggr_reset |= !lrbp->intr_cmd;
> -
> - if (cmd) {
> - result = ufshcd_transfer_rsp_status(hba, lrbp);
> - scsi_dma_unmap(cmd);
> - cmd->result = result;
> - /* Mark completed command as NULL in LRB */
> - lrbp->cmd = NULL;
> - clear_bit_unlock(index, &hba->lrb_in_use);
> - /* Do not touch lrbp after scsi done */
> - cmd->scsi_done(cmd);
> - } else if (lrbp->command_type ==
> - UTP_CMD_TYPE_DEV_MANAGE) {
> - if (hba->dev_cmd.complete)
> - complete(hba->dev_cmd.complete);
> - }
> - } /* end of if */
> - } /* end of for */
> + for_each_set_bit(index, &completed_reqs, hba->nutrs) {
> + lrbp = &hba->lrb[index];
> + cmd = lrbp->cmd;
> + if (cmd) {
> + result = ufshcd_transfer_rsp_status(hba, lrbp);
> + scsi_dma_unmap(cmd);
> + cmd->result = result;
> + /* Mark completed command as NULL in LRB */
> + lrbp->cmd = NULL;
> + clear_bit_unlock(index, &hba->lrb_in_use);
> + /* Do not touch lrbp after scsi done */
> + cmd->scsi_done(cmd);
> + } else if (lrbp->command_type == UTP_CMD_TYPE_DEV_MANAGE) {
> + if (hba->dev_cmd.complete)
> + complete(hba->dev_cmd.complete);
> + }
> + } /* end of for_each_set_bit */
>
> /* clear corresponding bits of completed commands */
> hba->outstanding_reqs ^= completed_reqs;
>
> /* we might have free'd some tags above */
> wake_up(&hba->dev_cmd.tag_wq);
> -
> - /* Reset interrupt aggregation counters */
> - if (int_aggr_reset)
> - ufshcd_config_int_aggr(hba, INT_AGGR_RESET);
> }
>
> /**
> @@ -2569,6 +2565,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
> int poll_cnt;
> u8 resp = 0xF;
> struct ufshcd_lrb *lrbp;
> + u32 reg;
>
> host = cmd->device->host;
> hba = shost_priv(host);
> @@ -2578,6 +2575,13 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
> if (!(test_bit(tag, &hba->outstanding_reqs)))
> goto out;
>
> + reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
> + if (!(reg & (1 << tag))) {
> + dev_err(hba->dev,
> + "%s: cmd was completed, but without a notifying intr, tag = %d",
> + __func__, tag);
> + }
> +
> lrbp = &hba->lrb[tag];
> for (poll_cnt = 100; poll_cnt; poll_cnt--) {
> err = ufshcd_issue_tm_cmd(hba, lrbp->lun, lrbp->task_tag,
> @@ -2586,8 +2590,6 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
> /* cmd pending in the device */
> break;
> } else if (!err && resp == UPIU_TASK_MANAGEMENT_FUNC_COMPL) {
> - u32 reg;
> -
> /*
> * cmd not pending in the device, check if it is
> * in transition.
--
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