linux-kernel - Re: [PATCH v5] libata: Add ATA_HORKAGE_NO_NCQ_ON

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Date:   Thu, 2 Sep 2021 22:50:04 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     Kate Hsuan <hpa@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Damien Le Moal <damien.lemoal@....com>,
        Tor Vic <torvic9@...lbox.org>, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] libata: Add ATA_HORKAGE_NO_NCQ_ON_AMD for Samsung 860
 and 870 SSD.

Hi Again,

On 9/2/21 10:46 PM, Hans de Goede wrote:
> Hi,
> 
> On 9/2/21 9:01 PM, Martin K. Petersen wrote:
>>
>> Hans,
>>
>>> So it looks like we actually need to disable NCQ for Samsung 860/870
>>> devices when the SATA controller has a vendor-id of PCI_VENDOR_ID_ATI
>>> rather then AMD.
>>
>> That's another great data point!
>>
>> I wonder if there actually is a Samsung problem (given that these drives
>> work fine on other controllers). Or if it is just the queued trim
>> handling that's broken on 1002:4391 controllers from ATI.
>>
>> When I originally experimented with queued trim I had systems I could
>> not get to work. But queued trim worked fine when the same drives were
>> connected to more modern chipsets (note that this was "did not work at
>> all" as opposed to "randomly corrupting data").
>>
>> Do we have any evidence at all of queued trim working with non-Samsung
>> drives on these controllers? Not sure how many modern SATA drives
>> actually implement this feature. Maybe the reason we see Samsung drives
>> in the bug reports is due to a combination of popularity and the fact
>> that these drives actually implement queued trim support.
> 
> The Samsung 860 / 870 series causing issues when queued trim support
> is enabled are quite wide-spread, covering many different controller
> models from all well known controller vendors (Intel, Asmedia, Marvell
> and AMD). So disabling queued-trim support definitely is the right
> thing to do (and we should have done so a long time ago, I am to
> blame for this not being done sooner).
> 
> As for your theory that it is really a problem with the controller
> and not the the SSDs, I honestly do not know, but I doubt it,
> there are no such reports with any other vendor's SSD or newer
> Samsung models, so this seems unlikely.

I just realized that all newer Samsung models are non SATA...

Still I cponsider it likely that some of the other vendors also
implement queued trim support and there are no reports of issues
with the other vendors' SSDs.

Regards,

Hans