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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uFU4OIs9F/yLqrMYUVlxWw6pgEIiuopLhBmOu5Fuqow=; b=nR9D6G6Y2ZP7I2/whCmsu0gPVzF1y6L7JsTrh6iHqIWPrKxST/TQAv25b+5/rW3Rl4 2BKi9Hi95X6ipizN7Mvxhyb8v6Jarf0b2ykPnxJcTB4CC/2PFnCLWEtFLG+AXDLJFEB6 Nd9O72iWqQuL2qjZ1JMndG+SKcaqdxoaQOVPIMkJx1xFR8ZgICO/Lm+3pAT5jktn3rRn FCek7E3D+SVnvs4T2LXR9AUzOG4fV5zwR/Xk0/8+A7yUnHDa7GIihEo1fY6r43gxum5+ 6yKeVG1WJQRpyCfSD6VcAtQ8EFiHy4/9T0vffB60BqAW/l0h6qMeAHrHzVf5bqG9s2MU LyEQ== X-Gm-Message-State: APjAAAXkmn9WvY0EgBxbm2VdNvsU+hziQS2tPIdpYeYqWUSnkmQTZdTi 7S5gwUREQAqMdBsZC3SnFUmpwz4ZL2LKpEHXH+romw== X-Google-Smtp-Source: APXvYqzncV6XQ6Dd9EawJUjJzIzJE9cfUCSVKW2n6gn77HQ6QKscHpWsEQSHolc4+ze5cvd7EbutVgVZldhCg4lqajM= X-Received: by 2002:a1c:3cc3:: with SMTP id j186mr19449123wma.119.1570455194493; Mon, 07 Oct 2019 06:33:14 -0700 (PDT) MIME-Version: 1.0 References: <20191007114253.30735-1-ard.biesheuvel@linaro.org> <20191007120721.GA21060@lst.de> <20191007122738.GA24804@lst.de> <20191007124843.GA53339@C02WT3WMHTD6> <20191007133227.GA54763@C02WT3WMHTD6> In-Reply-To: <20191007133227.GA54763@C02WT3WMHTD6> From: Ard Biesheuvel Date: Mon, 7 Oct 2019 15:33:03 +0200 Message-ID: Subject: Re: [PATCH v3] nvme: retain split access workaround for capability reads To: Keith Busch X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191007_063316_051630_07635C23 X-CRM114-Status: GOOD ( 15.13 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: axboe@fb.com, Ilias Apalodimas , Christoph Hellwig , linux-nvme@lists.infradead.org, sagi@grimberg.me Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, 7 Oct 2019 at 15:32, Keith Busch wrote: > > On Mon, Oct 07, 2019 at 03:20:11PM +0200, Ard Biesheuvel wrote: > > On Mon, 7 Oct 2019 at 14:48, Keith Busch 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. > */ Thanks Keith. I'll respin with that. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme