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From: Jaegeuk Kim <jaegeuk@kernel.org>
To: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
	kernel-team@android.com
Cc: cang@codeaurora.org, alim.akhtar@samsung.com,
	avri.altman@wdc.com, bvanassche@acm.org,
	martin.petersen@oracle.com, stanley.chu@mediatek.com,
	Jaegeuk Kim <jaegeuk@kernel.org>,
	Asutosh Das <asutoshd@codeaurora.org>
Subject: [PATCH v5 6/7] scsi: ufs: fix clkgating on/off correctly
Date: Tue, 17 Nov 2020 08:58:38 -0800
Message-ID: <20201117165839.1643377-7-jaegeuk@kernel.org> (raw)
In-Reply-To: <20201117165839.1643377-1-jaegeuk@kernel.org>

The below call stack prevents clk_gating at every IO completion.
We can remove the condition, ufshcd_any_tag_in_use(), since clkgating_work
will check it again.

ufshcd_complete_requests(struct ufs_hba *hba)
  ufshcd_transfer_req_compl()
    __ufshcd_transfer_req_compl()
      __ufshcd_release(hba)
        if (ufshcd_any_tag_in_use() == 1)
           return;
  ufshcd_tmc_handler(hba);
    blk_mq_tagset_busy_iter();

Note that, this still requires a work to deal with a potential racy condition
when user sets clkgating.delay_ms to very small value. That can cause preventing
clkgating by the check of ufshcd_any_tag_in_use() in gate_work.

Fixes: 7252a3603015 ("scsi: ufs: Avoid busy-waiting by eliminating tag conflicts")
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index b8a54d09e750..86c8dee01ca9 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1746,7 +1746,7 @@ static void __ufshcd_release(struct ufs_hba *hba)
 
 	if (hba->clk_gating.active_reqs || hba->clk_gating.is_suspended ||
 	    hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL ||
-	    ufshcd_any_tag_in_use(hba) || hba->outstanding_tasks ||
+	    hba->outstanding_tasks ||
 	    hba->active_uic_cmd || hba->uic_async_done ||
 	    hba->clk_gating.state == CLKS_OFF)
 		return;
-- 
2.29.2.299.gdc1121823c-goog


  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-17 16:58 [PATCH v5 0/5] scsi: ufs: add some fixes Jaegeuk Kim
2020-11-17 16:58 ` [PATCH v5 1/7] scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF Jaegeuk Kim
2020-11-18  3:54   ` Can Guo
2020-11-17 16:58 ` [PATCH v5 2/7] scsi: ufs: atomic update for clkgating_enable Jaegeuk Kim
2020-11-18  3:54   ` Can Guo
2020-11-17 16:58 ` [PATCH v5 3/7] scsi: ufs: clear UAC for FFU and RPMB LUNs Jaegeuk Kim
2020-11-17 16:58 ` [PATCH v5 4/7] scsi: ufs: use WQ_HIGHPRI for gating work Jaegeuk Kim
2020-11-17 16:58 ` [PATCH v5 5/7] scsi: add more contexts in the ufs tracepoints Jaegeuk Kim
2020-11-17 16:58 ` Jaegeuk Kim [this message]
2020-11-17 16:58 ` [PATCH v5 7/7] scsi: ufs: show lba and length for unmap commands Jaegeuk Kim
2020-11-18  1:11   ` Can Guo
2020-11-20  3:01 ` [PATCH v5 0/5] scsi: ufs: add some fixes Martin K. Petersen
2020-11-24  3:58 ` Martin K. Petersen

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