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Date:   Sun, 7 May 2023 23:51:42 +0900
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Subject: Re: [PATCH v2] ata: libata-scsi: Fix get identity data failed
To:     yangxingui <yangxingui@huawei.com>, jejb@linux.ibm.com,
        martin.petersen@oracle.com, john.g.garry@oracle.com
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
        linuxarm@huawei.com, prime.zeng@hisilicon.com,
        kangfenglong@huawei.com
References: <20230505025712.19438-1-yangxingui@huawei.com>
 <291f1d97-9195-45ac-8e12-058f5c797277@kernel.org>
 <02d36ee9-cdad-454d-d822-95442d7bd67b@huawei.com>
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From:   Damien Le Moal <dlemoal@kernel.org>
Organization: Western Digital Research
In-Reply-To: <02d36ee9-cdad-454d-d822-95442d7bd67b@huawei.com>
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On 2023/05/05 18:06, yangxingui wrote:
> 
> 
> On 2023/5/5 16:17, Damien Le Moal wrote:
>> On 2023/05/05 11:57, Xingui Yang wrote:
>>> The function ata_get_identity() uses the helper ata_scsi_find_dev() to get
>>> the ata_device structure of a scsi device. However, when the ata device is
>>> managed by libsas, ata_scsi_find_dev() returns NULL, turning
>>> ata_get_identity() into a nop and always returns -ENOMSG.
>>
>> What do you do to hit the issue ? A while back for me it was the queue depth
>> setting causing problems. As Garry mentioned, this led to patch 141f3d6256e5
>> ("ata: libata-sata: Fix device queue depth control").
> Attempt to return the correct value at ata_scsi_find_dev() instead of 
> NULL, when the ata device is managed by libsas?

That I understand. My question is *what* user operation/command triggers this ?
Because on my test setup, under normal use, I do not see this issue (beside what
was already corrected with the queue depth control). Is the issue showing up
when using passthrough commands only ?


-- 
Damien Le Moal
Western Digital Research