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SubjectRe: [PATCH v4 7/7] scsi: ufs: Fix error handing during hibern8 enter
On 2019-11-14 19:06, Avri Altman wrote:
>>
>>
>> From: Subhash Jadavani <subhashj@codeaurora.org>
>>
>> During clock gating (ufshcd_gate_work()), we first put the link
>> hibern8 by
>> calling ufshcd_uic_hibern8_enter() and if ufshcd_uic_hibern8_enter()
>> returns
>> success (0) then we gate all the clocks.
>> Now let’s zoom in to what ufshcd_uic_hibern8_enter() does internally:
>> It calls __ufshcd_uic_hibern8_enter() which on detecting the
>> LINERESET,
>> initiates the full recovery and puts the link back to highest HS gear
>> and returns
>> success (0) to ufshcd_uic_hibern8_enter() which is the issue as link
>> is still in
>> active state due to recovery!
>> Now ufshcd_uic_hibern8_enter() returns success to ufshcd_gate_work()
>> and
>> hence it goes ahead with gating the UFS clock while link is still in
>> active state
>> hence I believe controller would raise UIC error interrupts. But when
>> we service
>> the interrupt, clocks might have already been disabled!
>>
>> This change fixes for this by returning failure from
>> __ufshcd_uic_hibern8_enter() if recovery succeeds as link is still not
>> in hibern8,
>> upon receiving the error ufshcd_hibern8_enter() would initiate retry
>> to put the
>> link state back into hibern8.
>>
>> Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> ---
>> drivers/scsi/ufs/ufshcd.c | 19 ++++++++++++++-----
>> 1 file changed, 14 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index
>> 7a5a904..934c27a 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -3891,15 +3891,24 @@ static int __ufshcd_uic_hibern8_enter(struct
>> ufs_hba *hba)
>> ktime_to_us(ktime_sub(ktime_get(),
>> start)), ret);
>>
>> if (ret) {
>> + int err;
>> +
>> dev_err(hba->dev, "%s: hibern8 enter failed. ret =
>> %d\n",
>> __func__, ret);
>>
>> /*
>> - * If link recovery fails then return error so that
>> caller
>> - * don't retry the hibern8 enter again.
>> + * If link recovery fails then return error code
>> (-ENOLINK)
>> + * returned ufshcd_link_recovery().
>> + * If link recovery succeeds then return -EAGAIN to
>> attempt
>> + * hibern8 enter retry again.
> You no longer returning -ENOLINK, and either way retrying, regardless
> of the error code.
> Better check that the commit log is still telling the correct story,
> taking into consideration all those recent fixes and all.
>

Thanks for pointing this.

Best Regards,
Can Guo.

>> */
>> - if (ufshcd_link_recovery(hba))
>> - ret = -ENOLINK;
>> + err = ufshcd_link_recovery(hba);
>> + if (err) {
>> + dev_err(hba->dev, "%s: link recovery failed",
>> __func__);
>> + ret = err;
>> + } else {
>> + ret = -EAGAIN;
>> + }
>> } else
>> ufshcd_vops_hibern8_notify(hba,
>> UIC_CMD_DME_HIBER_ENTER,
>>
>> POST_CHANGE); @@ -3913,7 +3922,7 @@
>> static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
>>
>> for (retries = UIC_HIBERN8_ENTER_RETRIES; retries > 0;
>> retries--) {
>> ret = __ufshcd_uic_hibern8_enter(hba);
>> - if (!ret || ret == -ENOLINK)
>> + if (!ret)
>> goto out;
>> }
>> out:
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>> Forum,
>> a Linux Foundation Collaborative Project

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