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Date:   Thu, 19 Jan 2023 07:14:52 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Janne Grunau <j@jannau.net>
Cc:     Hector Martin <marcan@marcan.st>, Sven Peter <sven@svenpeter.dev>,
        Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        Eric Curtin <ecurtin@redhat.com>, asahi@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org,
        linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] nvme-apple: Reset controller during shutdown
Message-ID: <20230119061452.GA17695@lst.de>
References: <20230114-apple-nvme-suspend-fixes-v6.2-v2-0-9157bf633dba@jannau.net> <20230114-apple-nvme-suspend-fixes-v6.2-v2-1-9157bf633dba@jannau.net> <20230118052450.GA24742@lst.de>
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Folks, can you chime in if this comment makes sense?  I'd really
like to send the patches off to Jens before rc5.

On Wed, Jan 18, 2023 at 06:24:50AM +0100, Christoph Hellwig wrote:
> On Tue, Jan 17, 2023 at 07:25:00PM +0100, Janne Grunau wrote:
> > +		/*
> > +		 * Always reset the NVMe controller on shutdown. The reset is
> > +		 * required to shutdown the co-processor cleanly.
> > +		 */
> 
> Hmm.  This comment doesn't seem to match the discussion we had last
> week.  Which would be:
> 
> 		/*
> 		 * NVMe requires a reset before setting up a controller to
> 		 * ensure it is in a clean state.  For NVMe PCIe this is
> 		 * done in the setup path to be able to deal with controllers
> 		 * in any kind of state.  For for Apple devices, the firmware
> 		 * will not be available at that time and the reset will
> 		 * time out.  Thus reset after shutting the NVMe controller
> 		 * down and before shutting the firmware down.
> 		 */
---end quoted text---