From: Keith Busch <kbusch@kernel.org>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: axboe@fb.com, Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Christoph Hellwig <hch@lst.de>,
linux-nvme@lists.infradead.org, sagi@grimberg.me
Subject: Re: [PATCH v3] nvme: retain split access workaround for capability reads
Date: Mon, 7 Oct 2019 07:32:27 -0600 [thread overview]
Message-ID: <20191007133227.GA54763@C02WT3WMHTD6> (raw)
In-Reply-To: <CAKv+Gu-2yBVx2sh1wZ4d8+eJ8ffc44be86=FNt6K4euh+J1+OA@mail.gmail.com>
On Mon, Oct 07, 2019 at 03:20:11PM +0200, Ard Biesheuvel wrote:
> On Mon, 7 Oct 2019 at 14:48, Keith Busch <kbusch@kernel.org> wrote:
> > If you explain this patch by saying it's to fix a host controller, then the
> > patch is no longer sufficient on it's own and should be fixed elsewhere,
> > perhaps by providing a special pci_ops structure for your controller.
>
> Fair enough. Any suggestions for the wording of the comment?
Something like this for the changelog:
Subject: nvme/pci: Split 8-byte reads
The nvme pci driver had split 8-byte register reads using lo_hi_readq() due to
nvme controllers that do not support that sized access. This behavior was
inadvertently changed to readq(), which may break those controllers. Restore
the previous behavior.
Fixes: 7fd8930f26be4 ("nvme: add a common helper to read Identify Controller data")
And the comment:
/*
* Split the 8-byte read into two 4-byte reads since all controllers
* support 4 byte register reads, but some do not support the larger
* access size.
*/
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next prev parent reply other threads:[~2019-10-07 13:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 11:42 [PATCH v3] nvme: retain split access workaround for capability reads Ard Biesheuvel
2019-10-07 12:07 ` Christoph Hellwig
2019-10-07 12:24 ` Ard Biesheuvel
2019-10-07 12:27 ` Christoph Hellwig
2019-10-07 12:32 ` Ard Biesheuvel
2019-10-07 12:47 ` Christoph Hellwig
2019-10-07 12:48 ` Keith Busch
2019-10-07 13:20 ` Ard Biesheuvel
2019-10-07 13:32 ` Keith Busch [this message]
2019-10-07 13:33 ` Ard Biesheuvel
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