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SubjectRe: [PATCH v4 5/5] scsi: ufs: fix clkgating on/off correctly
On 2020-10-27 03:51, Jaegeuk Kim wrote:
> 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;

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