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From: Christoph Hellwig <hch@infradead.org>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Jens Axboe <axboe@kernel.dk>,
	linux-ide@vger.kernel.org
Subject: Re: [PATCH] ahci: Add Intel Emmitsburg PCH RAID PCI IDs
Date: Mon, 23 Nov 2020 11:38:01 +0000	[thread overview]
Message-ID: <20201123113801.GA15759@infradead.org> (raw)
In-Reply-To: <20201123112622.GB2495@lahna.fi.intel.com>

On Mon, Nov 23, 2020 at 01:26:22PM +0200, Mika Westerberg wrote:
> On Mon, Nov 23, 2020 at 10:09:17AM +0000, Christoph Hellwig wrote:
> > On Fri, Nov 20, 2020 at 12:53:09PM +0200, Mika Westerberg wrote:
> > > On Thu, Nov 19, 2020 at 04:50:22PM +0000, Christoph Hellwig wrote:
> > > > On Thu, Nov 19, 2020 at 01:43:18PM +0300, Mika Westerberg wrote:
> > > > > Add Intel Emmitsburg PCH RAID PCI IDs to the list of supported
> > > > > controllers.
> > > > 
> > > > Stupid question: what would it to get Intel to finally report the
> > > > correct classcode after all the time?  The amount of IDs we need to list
> > > > is getting ridiculous.
> > > 
> > > What is the correct class code in this case that it works with the AHCI
> > > driver?
> > > 
> > > I think (not 100% sure) it reports standard AHCI class code when it is
> > > not in RAID mode but these PCI IDs are for the RAID mode.
> > 
> > The right class code is the AHCI one.  The so called RAID mode doesn't
> > change the operation of the device at all (except for sometimes hiding
> > NVMe devices that are a different PCIe function to start with).
> 
> Thanks. I looked at the AHCI spec (1.3.1) and it says this regarding the
> class code (CC) field:
> 
>   Informative Note: For HBAs that support RAID, the Sub Class Code reset
>   value should be 04h and the Programming Interface reset value should be
>   00h.
> 
> I think this is what the controller is doing when in "RAID mode".

The point is: these AHCI controllers do not support RAID in form
despite the confusing naming.

  reply	other threads:[~2020-11-23 11:38 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-19 10:43 [PATCH] ahci: Add Intel Emmitsburg PCH RAID PCI IDs Mika Westerberg
2020-11-19 16:50 ` Christoph Hellwig
2020-11-20 10:53   ` Mika Westerberg
2020-11-23 10:09     ` Christoph Hellwig
2020-11-23 11:26       ` Mika Westerberg
2020-11-23 11:38         ` Christoph Hellwig [this message]
2020-11-23 12:28           ` Mika Westerberg
2020-11-23 12:51             ` Christoph Hellwig
2020-11-25 14:44               ` Mika Westerberg
2022-04-02  0:43           ` Williams, Dan J
2020-12-16 12:34 ` Mika Westerberg

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