[PATCH 5.10 166/717] scsi: ufs: Fix clkgating on/off

Greg Kroah-Hartman
2020-12-28T15:12:35Z

From: Jaegeuk Kim <jaegeuk@kernel.org>

[ Upstream commit 8eb456be75af7e5a7ac0cd223eaa198cf7ee2ac1 ]

The following call stack prevents clk_gating at every I/O 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 work to deal with a potential race 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.

Link: https://lore.kernel.org/r/20201117165839.1643377-7-jaegeuk@kernel.org
Fixes: 7252a3603015 ("scsi: ufs: Avoid busy-waiting by eliminating tag conflicts")
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.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 1ad7d6c130f5b..911aba3e7675c 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1751,7 +1751,7 @@ 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;
--
2.27.0