From patchwork Mon Oct 20 08:46:14 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Boris Brezillon X-Patchwork-Id: 401020 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2001:1868:205::9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4820814008B for ; Mon, 20 Oct 2014 19:49:22 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Xg8cq-0000jH-If; Mon, 20 Oct 2014 08:47:36 +0000 Received: from down.free-electrons.com ([37.187.137.238] helo=mail.free-electrons.com) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Xg8cK-0000Zg-1o; Mon, 20 Oct 2014 08:47:05 +0000 Received: by mail.free-electrons.com (Postfix, from userid 106) id 87A415001; Mon, 20 Oct 2014 10:46:43 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on mail.free-electrons.com X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,SHORTCIRCUIT, URIBL_BLOCKED shortcircuit=ham autolearn=disabled version=3.4.0 Received: from localhost.localdomain (col31-4-88-188-83-94.fbx.proxad.net [88.188.83.94]) by mail.free-electrons.com (Postfix) with ESMTPSA id EB2B44FFE; Mon, 20 Oct 2014 10:46:42 +0200 (CEST) From: Boris Brezillon To: David Woodhouse , Brian Norris , linux-mtd@lists.infradead.org, Huang Shijie Subject: [PATCH v4 1/4] mtd: nand: provide detailed description for raw read/write page methods Date: Mon, 20 Oct 2014 10:46:14 +0200 Message-Id: <1413794777-32220-2-git-send-email-boris.brezillon@free-electrons.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1413794777-32220-1-git-send-email-boris.brezillon@free-electrons.com> References: <1413794777-32220-1-git-send-email-boris.brezillon@free-electrons.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141020_014704_275035_C5A9122C X-CRM114-Status: GOOD ( 12.15 ) X-Spam-Score: -0.5 (/) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-0.5 points) pts rule name description ---- ---------------------- -------------------------------------------------- -1.4 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 1.0 SPF_SOFTFAIL SPF: sender does not match SPF record (softfail) Cc: Mike Voytovich , Boris Brezillon , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Roy Lee X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-mtd" Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org read_page_raw and write_page_raw method description is not clear enough. It clearly specifies that ECC correction should not be involved but does not talk about specific layout (by layout I mean where in-band and out-of-band data are stored on the NAND media) used by NAND/ECC controllers. Those specific layouts might impact MTD users and thus should be hidden (as already done in the standard NAND_ECC_HW_SYNDROME implementation). Clearly state this constraint in the nand_ecc_ctrl struct documentation. Signed-off-by: Boris Brezillon --- include/linux/mtd/nand.h | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h index e4d451e..b14d190 100644 --- a/include/linux/mtd/nand.h +++ b/include/linux/mtd/nand.h @@ -455,8 +455,21 @@ struct nand_hw_control { * be provided if an hardware ECC is available * @calculate: function for ECC calculation or readback from ECC hardware * @correct: function for ECC correction, matching to ECC generator (sw/hw) - * @read_page_raw: function to read a raw page without ECC - * @write_page_raw: function to write a raw page without ECC + * @read_page_raw: function to read a raw page without ECC. This function + * should hide the specific layout used by the ECC + * controller and always return contiguous in-band and + * out-of-band data even if they're not stored + * contiguously on the NAND chip (e.g. + * NAND_ECC_HW_SYNDROME interleaves in-band and + * out-of-band data). + * @write_page_raw: function to write a raw page without ECC. This function + * should hide the specific layout used by the ECC + * controller and consider the passed data as contiguous + * in-band and out-of-band data. ECC controller is + * responsible for doing the appropriate transformations + * to adapt to its specific layout (e.g. + * NAND_ECC_HW_SYNDROME interleaves in-band and + * out-of-band data). * @read_page: function to read a page according to the ECC generator * requirements; returns maximum number of bitflips corrected in * any single ECC step, 0 if bitflips uncorrectable, -EIO hw error