lkml.org 
[lkml]   [2017]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3 14/23] scsi: hisi_sas: add v3 cq interrupt handler
From
Date
On 08/06/2017 08:34, Christoph Hellwig wrote:
> Hi John,
>
> sorry for dropping the ball, but your repost reminded me.
>
> On Thu, Jun 01, 2017 at 11:36:55AM +0100, John Garry wrote:
>> In the command completion code we need to check for abnormal completion due
>> to underflow, but ignore it when it occurs in some commands, like inquiry.
>> This is why we check for rw command - it is equivalent to !inquiry.
>>
>> I'll see if we can change the check to explicitly ignore certain commands
>> which complete abnormally with underflow.
>
> In general it should be up to the higher level and not the driver
> to detect underflow, and that's how most (hopefully all, but I won't
> bet on some older ones) of our drivers operate.
>

Hi Christoph,

Right, I see most LLDDs will not check for underflow; but, FWIW, I do
see scsi_cmnd.underflow referenced in some...

However, for drivers using libsas, we detect underflow for the reason
just so libsas knows the sas_task status (SAS_DATA_UNDERRUN) and sets
the scsi cmd result properly (and also the residual) in sas_end_task().

We used this method for the predecessor hw driver, and I think that we
can revert to it.

Much appreciated,
John

>>
>>> What about 32-byte CDs or things like Write Same?
>>>
>>
>> You're talking about VARIABLE_LENGTH_CMD (opcode 0x7f) for 32-byte CDs,
>> right?
>
> Yes.
>
> .
>


\
 
 \ /
  Last update: 2017-06-12 01:27    [W:0.201 / U:0.232 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site