From patchwork Sun Feb 21 12:52:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Markus Pargmann X-Patchwork-Id: 8368341 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 779C69F314 for ; Sun, 21 Feb 2016 12:55:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 8154F2041D for ; Sun, 21 Feb 2016 12:55:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7EB722041C for ; Sun, 21 Feb 2016 12:55:14 +0000 (UTC) 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 1aXTVd-0005qx-NZ; Sun, 21 Feb 2016 12:53:09 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aXTVa-0005nN-Ph for linux-arm-kernel@lists.infradead.org; Sun, 21 Feb 2016 12:53:07 +0000 Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7]) by metis.ext.pengutronix.de with esmtps (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1aXTUq-0003ky-Ac; Sun, 21 Feb 2016 13:52:20 +0100 Received: from mpa by dude.hi.pengutronix.de with local (Exim 4.86) (envelope-from ) id 1aXTUm-0006da-BJ; Sun, 21 Feb 2016 13:52:16 +0100 From: Markus Pargmann To: Han Xu , David Woodhouse , Boris BREZILLON Subject: [PATCH RESEND] gpmi-nand: Handle ECC Errors in erased pages Date: Sun, 21 Feb 2016 13:52:06 +0100 Message-Id: <1456059126-25469-1-git-send-email-mpa@pengutronix.de> X-Mailer: git-send-email 2.7.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: mpa@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160221_045307_022699_DD491C2C X-CRM114-Status: GOOD ( 16.05 ) X-Spam-Score: -1.9 (-) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fabio Estevam , Markus Pargmann , linux-mtd@lists.infradead.org, kernel@pengutronix.de, Huang Shijie , Brian Norris , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP ECC is only calculated for written pages. As erased pages are not actively written the ECC is always invalid. For this purpose the Hardware BCH unit is able to check for erased pages and does not raise an ECC error in this case. This behaviour can be influenced using the BCH_MODE register which sets the number of allowed bitflips in an erased page. Unfortunately the unit is not capable of fixing the bitflips in memory. To avoid complete software checks for erased pages, we can simply check buffers with uncorrectable ECC errors because we know that any erased page with errors is uncorrectable by the BCH unit. This patch adds the generic nand_check_erased_ecc_chunk() to gpmi-nand to correct erased pages. To have the valid data in the buffer before using them, this patch moves the read_page_swap_end() call before the ECC status checking for-loop. Signed-off-by: Markus Pargmann --- drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 49 ++++++++++++++++++++++++++++++---- 1 file changed, 44 insertions(+), 5 deletions(-) diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c index 235ddcb58f39..ce5a21252102 100644 --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c @@ -1035,14 +1035,58 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip, /* Loop over status bytes, accumulating ECC status. */ status = auxiliary_virt + nfc_geo->auxiliary_status_offset; + read_page_swap_end(this, buf, nfc_geo->payload_size, + this->payload_virt, this->payload_phys, + nfc_geo->payload_size, + payload_virt, payload_phys); + for (i = 0; i < nfc_geo->ecc_chunk_count; i++, status++) { if ((*status == STATUS_GOOD) || (*status == STATUS_ERASED)) continue; if (*status == STATUS_UNCORRECTABLE) { + int flips; + + /* + * The ECC hardware has an uncorrectable ECC status + * code in case we have bitflips in an erased page. As + * nothing was written into this subpage the ECC is + * obviously wrong and we can not trust it. We assume + * at this point that we are reading an erased page and + * try to correct the bitflips in buffer up to + * ecc_strength bitflips. If this is a page with random + * data, we exceed this number of bitflips and have a + * ECC failure. Otherwise we use the corrected buffer. + */ + if (i == 0) { + /* The first block includes metadata */ + flips = nand_check_erased_ecc_chunk( + buf + i * nfc_geo->ecc_chunk_size, + nfc_geo->ecc_chunk_size, + NULL, 0, + auxiliary_virt, + nfc_geo->metadata_size, + nfc_geo->ecc_strength); + } else { + flips = nand_check_erased_ecc_chunk( + buf + i * nfc_geo->ecc_chunk_size, + nfc_geo->ecc_chunk_size, + NULL, 0, + NULL, 0, + nfc_geo->ecc_strength); + } + + if (flips > 0) { + max_bitflips = max_t(unsigned int, max_bitflips, + flips); + mtd->ecc_stats.corrected += flips; + continue; + } + mtd->ecc_stats.failed++; continue; } + mtd->ecc_stats.corrected += *status; max_bitflips = max_t(unsigned int, max_bitflips, *status); } @@ -1062,11 +1106,6 @@ static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip, chip->oob_poi[0] = ((uint8_t *) auxiliary_virt)[0]; } - read_page_swap_end(this, buf, nfc_geo->payload_size, - this->payload_virt, this->payload_phys, - nfc_geo->payload_size, - payload_virt, payload_phys); - return max_bitflips; }