linux-kernel - Re: [PATCH v3 09/15] scsi: ufs: add retries for hibern8 enter

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Date:	Sun, 25 Oct 2015 13:45:22 -0000
From:	ygardi@...eaurora.org
To:	"Akinobu Mita" <akinobu.mita@...il.com>
Cc:	"Yaniv Gardi" <ygardi@...eaurora.org>,
	"Rob Herring" <robherring2@...il.com>,
	"Jej B" <james.bottomley@...senpartnership.com>,
	"Paul Bolle" <pebolle@...cali.nl>,
	"Christoph Hellwig" <hch@...radead.org>,
	"LKML" <linux-kernel@...r.kernel.org>,
	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	linux-arm-msm@...r.kernel.org, "Santosh Y" <santoshsy@...il.com>,
	linux-scsi-owner@...r.kernel.org,
	"Subhash Jadavani" <subhashj@...eaurora.org>,
	"Gilad Broner" <gbroner@...eaurora.org>,
	"Dolev Raviv" <draviv@...eaurora.org>,
	"Vinayak Holikatti" <vinholikatti@...il.com>,
	"James E.J. Bottomley" <jbottomley@...n.com>
Subject: Re: [PATCH v3 09/15] scsi: ufs: add retries for hibern8 enter

> 2015-09-02 19:13 GMT+09:00 Yaniv Gardi <ygardi@...eaurora.org>:
>> If hibern8 enter command fails then UFS link state may be unknown which
>> may result into timeout of all the commands issued after failure.
>>
>> This change does 2 things (for pre-defined number of retry counts) after
>> hibern8 enter failure:
>> 1. Recovers the UFS link to active state
>> 2. If link is recovered to active state, tries to put the UFS link in
>>    hibern8 enter again until retry count expires.
>>
>> Signed-off-by: Subhash Jadavani <subhashj@...eaurora.org>
>> Signed-off-by: Yaniv Gardi <ygardi@...eaurora.org>
>>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 26 ++++++++++++++++++++++++--
>>  1 file changed, 24 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index 8d5bdf0..5800b08 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -75,6 +75,9 @@
>>  /* maximum number of link-startup retries */
>>  #define DME_LINKSTARTUP_RETRIES 3
>>
>> +/* Maximum retries for Hibern8 enter */
>> +#define UIC_HIBERN8_ENTER_RETRIES 3
>> +
>>  /* maximum number of reset retries before giving up */
>>  #define MAX_HOST_RESET_RETRIES 5
>>
>> @@ -2389,13 +2392,32 @@ out:
>>         return ret;
>>  }
>>
>> -static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
>> +static int __ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
>>  {
>> +       int ret;
>>         struct uic_command uic_cmd = {0};
>>
>>         uic_cmd.command = UIC_CMD_DME_HIBER_ENTER;
>> +       ret = ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
>> +
>> +       if (ret)
>> +               dev_err(hba->dev, "%s: hibern8 enter failed. ret = %d",
>> +                       __func__, ret);
>
> This format string is not terminated with '\n'.
> (I found several same issues in ufshcd.c)

correct. will be modified in the next v4.
>
>> +
>> +       return ret;
>> +}
>> +
>> +static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
>> +{
>> +       int ret = 0, retries;
>>
>
> 'ret' will soon be initialized in the loop anyway, so it is unnecessary
> to initialized here.

correct but, in order to be on the safe side, better to leave this
initialization here, as if UIC_HIBERN8_ENTER_RETRIES is modified to 0, we
will never get into the for-loop, and thus, ret will be un initialized.


>
>> -       return ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
>> +       for (retries = UIC_HIBERN8_ENTER_RETRIES; retries > 0;
>> retries--) {
>> +               ret = __ufshcd_uic_hibern8_enter(hba);
>> +               if (!ret || ret == -ENOLINK)
>> +                       goto out;
>> +       }
>> +out:
>> +       return ret;
>>  }
>>
>>  static int ufshcd_uic_hibern8_exit(struct ufs_hba *hba)
>> --
>> 1.8.5.2
>>
>> --
>> QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a
>> member of Code Aurora Forum, hosted by The Linux Foundation
>> --
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>


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