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Date:   Tue, 29 Oct 2019 10:14:30 +0800
From:   cang@codeaurora.org
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     asutoshd@codeaurora.org, nguyenb@codeaurora.org,
        rnayak@codeaurora.org, linux-scsi@vger.kernel.org,
        kernel-team@android.com, saravanak@google.com, salyzyn@google.com,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 1/5] scsi: Adjust DBD setting in mode sense for caching
 mode page per LLD
In-Reply-To: <0ca52845-10ec-3310-83f7-81bdb635ec12@acm.org>
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 <0ca52845-10ec-3310-83f7-81bdb635ec12@acm.org>
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On 2019-10-28 22:58, Bart Van Assche wrote:
> On 10/27/19 8:50 PM, Can Guo wrote:
>> Host sends MODE_SENSE_10 with caching mode page, to check if the 
>> device
>> supports the cache feature.
>> Some LLD standards requires DBD field to be set to 1.
> 
> Which LLD standard are you referring to? Please mention at least one
> name of such a standard in the patch description.
> 

Hi Bart, Thank you for your review.

The LLD standard here is UFS. I will update the commit message and 
re-upload it later.

Thanks,

Can Guo

>> Change-Id: I0c8752c1888654942d6d7e6e0f6dc197033ac326
> 
> Change-IDs should be left out from upstream patches. Does the presence
> of this ID mean that this patch has not been verified with checkpatch?
> From the checkpatch source code:
> 
> # Check for unwanted Gerrit info
> if ($in_commit_log && $line =~ /^\s*change-id:/i) {
> 	ERROR("GERRIT_CHANGE_ID",
> 	      "Remove Gerrit Change-Id's before submitting upstream.\n"\
> 		 . $herecurr);
> }
> 

Sorry, forgot to remove the change-id.

>> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
>> index aab4ed8..6d8194f 100644
>> --- a/drivers/scsi/sd.c
>> +++ b/drivers/scsi/sd.c
>> @@ -2629,6 +2629,7 @@ static int sd_try_rc16_first(struct scsi_device 
>> *sdp)
>>   {
>>   	int len = 0, res;
>>   	struct scsi_device *sdp = sdkp->device;
>> +	struct Scsi_Host *host = sdp->host;
>>     	int dbd;
>>   	int modepage;
>> @@ -2660,7 +2661,10 @@ static int sd_try_rc16_first(struct scsi_device 
>> *sdp)
>>   		dbd = 8;
>>   	} else {
>>   		modepage = 8;
>> -		dbd = 0;
>> +		if (host->set_dbd_for_caching)
>> +			dbd = 8;
>> +		else
>> +			dbd = 0;
>>   	}
>>     	/* cautiously ask */
>> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
>> index 2c3f0c5..3900987 100644
>> --- a/include/scsi/scsi_host.h
>> +++ b/include/scsi/scsi_host.h
>> @@ -650,6 +650,12 @@ struct Scsi_Host {
>>   	unsigned no_scsi2_lun_in_cdb:1;
>>     	/*
>> +	 * Set "DBD" field in mode_sense caching mode page in case it is
>> +	 * mandatory by LLD standard.
>> +	 */
>> +	unsigned set_dbd_for_caching:1;
>> +
>> +	/*
>>   	 * Optional work queue to be utilized by the transport
>>   	 */
>>   	char work_q_name[20];
> 
> Since this patch by itself has no effect, please resubmit this patch
> together with the LLD patch that sets set_dbd_for_caching.
> 
> Thanks,
> 
> Bart.