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Message-ID: <e6f9921d-0fb6-da30-4dc5-53b4cb7b5270@redhat.com>
Date: Wed, 1 Sep 2021 10:55:37 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: torvic9@...lbox.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"hpa@...hat.com" <hpa@...hat.com>
Cc: "linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>,
"axboe@...nel.dk" <axboe@...nel.dk>,
"damien.lemoal@....com" <damien.lemoal@....com>
Subject: Re: [PATCH v4] libata: Add ATA_HORKAGE_NO_NCQ_ON_AMD for Samsung 860
and 870 SSD.
Hi Tor,
On 9/1/21 9:37 AM, torvic9@...lbox.org wrote:
> (Sorry for not doing a proper reply)
>
> Hello,
> Noob here.
> I have a Samsung 860 Pro connected to a AMD X570 chipset mainboard and
> it just works flawlessly on 5.13 and 5.14.
> Are you sure that *every* 860/870 is concerned by this problem on
> *every* AMD controller?
I am pretty sure that every 860 / 870 EVO is affected,
I am not sure if the PRO is also affected.
As for *every* AMD controller, chances are that more recent
AMD controllers are fine.
We have been trying to resolve various issues with this combo
for a long time now, see:
https://bugzilla.kernel.org/show_bug.cgi?id=201693
https://bugzilla.kernel.org/show_bug.cgi?id=203475
> Isn't this too restrictive?
> Or am I simply missing something?
The problem is that when users are hit by this they end up with
a non functional system and even fs / data corruption. Where
as OTOH disabling NCQ leads to a (significant) performance
degradation but affected systems will still work fine.
So I believe that it is best to err on the safe side here
and accept the performance degradation as a trade-of for
fixing the fs / data corruption.
With that said, I do believe that we should allow re-enabling
ncq on this combo through libata.force on the kernel cmdline
by adding this extra bit to the patch:
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6136,6 +6136,8 @@ static int __init ata_parse_force_one(char **cur,
{ "ncq", .horkage_off = ATA_HORKAGE_NONCQ },
{ "noncqtrim", .horkage_on = ATA_HORKAGE_NO_NCQ_TRIM },
{ "ncqtrim", .horkage_off = ATA_HORKAGE_NO_NCQ_TRIM },
+ { "noncqamd", .horkage_on = ATA_HORKAGE_NO_NCQ_ON_AMD },
+ { "ncqamd", .horkage_off = ATA_HORKAGE_NO_NCQ_ON_AMD },
{ "dump_id", .horkage_on = ATA_HORKAGE_DUMP_ID },
{ "pio0", .xfer_mask = 1 << (ATA_SHIFT_PIO + 0) },
{ "pio1", .xfer_mask = 1 << (ATA_SHIFT_PIO + 1) },
And I will also add a comment to both linked bugs to see if we can maybe
exclude the pro models from this quirk and if we can maybe narrow it down
to a subset of the AMD SATA controllers.
But that narrowing down is probably best done as a follow up fix, while just
going with this "err on the safe side" approach for now.
Regards,
Hans
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