| From f2a785ac23125fa0774327d39e837e45cf28fe92 Mon Sep 17 00:00:00 2001 |
| From: Venkat Gopalakrishnan <venkatg@codeaurora.org> |
| Date: Mon, 17 Oct 2016 17:10:53 -0700 |
| Subject: scsi: ufshcd: Fix race between clk scaling and ungate work |
| |
| From: Venkat Gopalakrishnan <venkatg@codeaurora.org> |
| |
| commit f2a785ac23125fa0774327d39e837e45cf28fe92 upstream. |
| |
| The ungate work turns on the clock before it exits hibern8, if the link |
| was put in hibern8 during clock gating work. There occurs a race |
| condition when clock scaling work calls ufshcd_hold() to make sure low |
| power states cannot be entered, but that returns by checking only |
| whether the clocks are on. This causes the clock scaling work to issue |
| UIC commands when the link is in hibern8 causing failures. Make sure we |
| exit hibern8 state before returning from ufshcd_hold(). |
| |
| Callstacks for race condition: |
| |
| ufshcd_scale_gear |
| ufshcd_devfreq_scale |
| ufshcd_devfreq_target |
| update_devfreq |
| devfreq_monitor |
| process_one_work |
| worker_thread |
| kthread |
| ret_from_fork |
| |
| ufshcd_uic_hibern8_exit |
| ufshcd_ungate_work |
| process_one_work |
| worker_thread |
| kthread |
| ret_from_fork |
| |
| Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org> |
| Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org> |
| Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> |
| Signed-off-by: Amit Pundir <amit.pundir@linaro.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/scsi/ufs/ufshcd.c | 15 +++++++++++++++ |
| 1 file changed, 15 insertions(+) |
| |
| --- a/drivers/scsi/ufs/ufshcd.c |
| +++ b/drivers/scsi/ufs/ufshcd.c |
| @@ -585,6 +585,21 @@ int ufshcd_hold(struct ufs_hba *hba, boo |
| start: |
| switch (hba->clk_gating.state) { |
| case CLKS_ON: |
| + /* |
| + * Wait for the ungate work to complete if in progress. |
| + * Though the clocks may be in ON state, the link could |
| + * still be in hibner8 state if hibern8 is allowed |
| + * during clock gating. |
| + * Make sure we exit hibern8 state also in addition to |
| + * clocks being ON. |
| + */ |
| + if (ufshcd_can_hibern8_during_gating(hba) && |
| + ufshcd_is_link_hibern8(hba)) { |
| + spin_unlock_irqrestore(hba->host->host_lock, flags); |
| + flush_work(&hba->clk_gating.ungate_work); |
| + spin_lock_irqsave(hba->host->host_lock, flags); |
| + goto start; |
| + } |
| break; |
| case REQ_CLKS_OFF: |
| if (cancel_delayed_work(&hba->clk_gating.gate_work)) { |
