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Commit 48eafd42 authored by Stanley Chu's avatar Stanley Chu Committed by Todd Kjos
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UPSTREAM: scsi: ufs: Fix possible infinite loop in ufshcd_hold 

In ufshcd_suspend(), after clk-gating is suspended and link is set
as Hibern8 state, ufshcd_hold() is still possibly invoked before
ufshcd_suspend() returns. For example, MediaTek's suspend vops may
issue UIC commands which would call ufshcd_hold() during the command
issuing flow.

Now if UFSHCD_CAP_HIBERN8_WITH_CLK_GATING capability is enabled,
then ufshcd_hold() may enter infinite loops because there is no
clk-ungating work scheduled or pending. In this case, ufshcd_hold()
shall just bypass, and keep the link as Hibern8 state.

Link: https://lore.kernel.org/r/20200809050734.18740-1-stanley.chu@mediatek.com


Reviewed-by: default avatarAvri Altman <avri.altman@wdc.com>
Co-developed-by: default avatarAndy Teng <andy.teng@mediatek.com>
Signed-off-by: default avatarAndy Teng <andy.teng@mediatek.com>
Signed-off-by: default avatarStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>

Bug: 166747994
(cherry picked from commit 93b6c5db06028a3b55122bbb74d0715dd8ca4ae0)
Change-Id: I595ee3f0da3b89e11cbe5d6d31ba7ce58b1757bc
Signed-off-by: default avatarStanley Chu <stanley.chu@mediatek.com>
parent 45f61ca7

drivers/scsi/ufs/ufshcd.c

+4 −1
Original line number Diff line number Diff line
@@ -1628,6 +1628,7 @@ static void ufshcd_ungate_work(struct work_struct *work) 
int ufshcd_hold(struct ufs_hba *hba, bool async)

{

	int rc = 0;

	bool flush_result;

	unsigned long flags;



	if (!ufshcd_is_clkgating_allowed(hba))
@@ -1654,7 +1655,9 @@ int ufshcd_hold(struct ufs_hba *hba, bool async) 
				break;

			}

			spin_unlock_irqrestore(hba->host->host_lock, flags);

			flush_work(&hba->clk_gating.ungate_work);

			flush_result = flush_work(&hba->clk_gating.ungate_work);

			if (hba->clk_gating.is_suspended && !flush_result)

				goto out;

			spin_lock_irqsave(hba->host->host_lock, flags);

			goto start;

		}