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Date:   Tue, 28 Jul 2020 10:21:38 +0800
From:   Can Guo <cang@codeaurora.org>
To:     Avri Altman <Avri.Altman@wdc.com>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        hongwus@codeaurora.org, rnayak@codeaurora.org,
        sh425.lee@samsung.com, linux-scsi@vger.kernel.org,
        kernel-team@android.com, saravanak@google.com, salyzyn@google.com,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 3/8] scsi: ufs-qcom: Fix schedule while atomic error in
 ufs_qcom_dump_dbg_regs
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Hi Avri,

On 2020-07-27 21:05, Avri Altman wrote:
>> Dumping testbus registers needs to sleep a bit intermittently as there 
>> are
>> too many of them. Skip them for those contexts where sleep is not 
>> allowed.
>> 
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> ---
>>  drivers/scsi/ufs/ufs-qcom.c | 15 +++++++++------
>>  1 file changed, 9 insertions(+), 6 deletions(-)
>> 
>> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
>> index 7da27ee..7831b2b 100644
>> --- a/drivers/scsi/ufs/ufs-qcom.c
>> +++ b/drivers/scsi/ufs/ufs-qcom.c
>> @@ -1651,13 +1651,16 @@ static void ufs_qcom_dump_dbg_regs(struct
>> ufs_hba *hba)
>>         ufshcd_dump_regs(hba, REG_UFS_SYS1CLK_1US, 16 * 4,
>>                          "HCI Vendor Specific Registers ");
>> 
>> -       /* sleep a bit intermittently as we are dumping too much data 
>> */
>>         ufs_qcom_print_hw_debug_reg_all(hba, NULL,
>> ufs_qcom_dump_regs_wrapper);
>> -       udelay(1000);
>> -       ufs_qcom_testbus_read(hba);
>> -       udelay(1000);
>> -       ufs_qcom_print_unipro_testbus(hba);
>> -       udelay(1000);
>> +
>> +       if (in_task()) {
>> +               /* sleep a bit intermittently as we are dumping too 
>> much data */
>> +               usleep_range(1000, 1100);
>> +               ufs_qcom_testbus_read(hba);
>> +               usleep_range(1000, 1100);
>> +               ufs_qcom_print_unipro_testbus(hba);
>> +               usleep_range(1000, 1100);
>> +       }
>>  }
> How about moving the intermittent sleep out of the check if preemption
> is disabled?
> And maybe then you need to switch back to uedlay?

I will just remove all the testbus prints in next version to save us 
time here.

Thanks,

Can Guo.