linux-kernel - Re: [PATCH v2] scsi: ufs: fix clkgating on/off correctly

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Message-ID: <20201016211826.GA3441410@google.com>
Date:   Fri, 16 Oct 2020 14:18:26 -0700
From:   jaegeuk@...nel.org
To:     linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Can Guo <cang@...eaurora.org>
Subject: Re: [PATCH v2] scsi: ufs: fix clkgating on/off correctly

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();

In addition, we have to avoid gate_work, if it was disabled.

Cc: Alim Akhtar <alim.akhtar@...sung.com>
Cc: Avri Altman <avri.altman@....com>
Cc: Can Guo <cang@...eaurora.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---

Change log from v1:
 - change the patch subject
 - fix clkgate.is_enable to work

 drivers/scsi/ufs/ufshcd.c | 5 +++--
 drivers/scsi/ufs/ufshcd.h | 5 +++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index a2db8182663d..75e8a76f20c7 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1729,9 +1729,10 @@ 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
-		|| ufshcd_eh_in_progress(hba))
+		|| ufshcd_eh_in_progress(hba)
+		|| ufshcd_is_clkgating_enabled(hba))
 		return;
 
 	hba->clk_gating.state = REQ_CLKS_OFF;
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 8344d8cb3678..09e59cb86e69 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -814,6 +814,11 @@ static inline bool ufshcd_is_auto_hibern8_supported(struct ufs_hba *hba)
 		!(hba->quirks & UFSHCD_QUIRK_BROKEN_AUTO_HIBERN8);
 }
 
+static inline bool ufshcd_is_clkgating_enabled(struct ufs_hba *hba)
+{
+	return hba->clk_gating.is_enabled;
+}
+
 static inline bool ufshcd_is_auto_hibern8_enabled(struct ufs_hba *hba)
 {
 	return FIELD_GET(UFSHCI_AHIBERN8_TIMER_MASK, hba->ahit) ? true : false;
-- 
2.29.0.rc1.297.gfa9743e501-goog