linux-kernel - Re: [PATCH v1 5/5] scsi: ufs: Complete pending requests in host reset and restore path

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Date:   Wed, 13 Nov 2019 11:01:44 +0800
From:   cang@...eaurora.org
To:     Alim Akhtar <alim.akhtar@...il.com>
Cc:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        rnayak@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Pedro Sousa <pedrom.sousa@...opsys.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Subhash Jadavani <subhashj@...eaurora.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 5/5] scsi: ufs: Complete pending requests in host reset
 and restore path

On 2019-11-13 10:24, Alim Akhtar wrote:
> Hi Can,
> 
> On Fri, Nov 8, 2019 at 1:50 PM Can Guo <cang@...eaurora.org> wrote:
>> 
>> In UFS host reset and restore path, before probe, we stop and start 
>> the
>> host controller once. After host controller is stopped, the pending
>> requests, if any, are cleared from the doorbell, but no completion IRQ
>> would be raised due to the hba is stopped.
>> These pending requests shall be completed along with the first NOP_OUT
>> command(as it is the first command which can raise a transfer 
>> completion
>> IRQ) sent during probe.
>> Since the OCSs of these pending requests are not SUCCESS(because they 
>> are
>> not yet literally finished), their UPIUs shall be dumped. When there 
>> are
>> multiple pending requests, the UPIU dump can be overwhelming and may 
>> lead
>> to stability issues because it is in atomic context.
>> Therefore, before probe, complete these pending requests right after 
>> host
>> controller is stopped.
>> 
>> Signed-off-by: Can Guo <cang@...eaurora.org>
>> ---
> Looks good, I hope this is tested on your platform.
> Reviewed-by: Alim Akhtar <alim.akhtar@...sung.com>
> 

Hi Alim,

Thanks for the review. We've tested it out on our platforms.

Best regards,
Can Guo.

>>  drivers/scsi/ufs/ufshcd.c | 20 +++++++-------------
>>  1 file changed, 7 insertions(+), 13 deletions(-)
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 5950a7c..4df4136 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -5404,8 +5404,8 @@ static void ufshcd_err_handler(struct 
>> work_struct *work)
>> 
>>         /*
>>          * if host reset is required then skip clearing the pending
>> -        * transfers forcefully because they will automatically get
>> -        * cleared after link startup.
>> +        * transfers forcefully because they will get cleared during
>> +        * host reset and restore
>>          */
>>         if (needs_reset)
>>                 goto skip_pending_xfer_clear;
>> @@ -6333,9 +6333,13 @@ static int ufshcd_host_reset_and_restore(struct 
>> ufs_hba *hba)
>>         int err;
>>         unsigned long flags;
>> 
>> -       /* Reset the host controller */
>> +       /*
>> +        * Stop the host controller and complete the requests
>> +        * cleared by h/w
>> +        */
>>         spin_lock_irqsave(hba->host->host_lock, flags);
>>         ufshcd_hba_stop(hba, false);
>> +       ufshcd_complete_requests(hba);
>>         spin_unlock_irqrestore(hba->host->host_lock, flags);
>> 
>>         /* scale up clocks to max frequency before full 
>> reinitialization */
>> @@ -6369,7 +6373,6 @@ static int ufshcd_host_reset_and_restore(struct 
>> ufs_hba *hba)
>>  static int ufshcd_reset_and_restore(struct ufs_hba *hba)
>>  {
>>         int err = 0;
>> -       unsigned long flags;
>>         int retries = MAX_HOST_RESET_RETRIES;
>> 
>>         do {
>> @@ -6379,15 +6382,6 @@ static int ufshcd_reset_and_restore(struct 
>> ufs_hba *hba)
>>                 err = ufshcd_host_reset_and_restore(hba);
>>         } while (err && --retries);
>> 
>> -       /*
>> -        * After reset the door-bell might be cleared, complete
>> -        * outstanding requests in s/w here.
>> -        */
>> -       spin_lock_irqsave(hba->host->host_lock, flags);
>> -       ufshcd_transfer_req_compl(hba);
>> -       ufshcd_tmc_handler(hba);
>> -       spin_unlock_irqrestore(hba->host->host_lock, flags);
>> -
>>         return err;
>>  }
>> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>>