Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965431AbcJQWHh (ORCPT ); Mon, 17 Oct 2016 18:07:37 -0400 Received: from mout.kundenserver.de ([212.227.126.187]:52302 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934489AbcJQWH3 (ORCPT ); Mon, 17 Oct 2016 18:07:29 -0400 From: Arnd Bergmann To: Boris Brezillon Cc: Linus Torvalds , linux-kernel@vger.kernel.org, Arnd Bergmann , Richard Weinberger , David Woodhouse , Brian Norris , Matthias Brugger , Jorge Ramirez-Ortiz , RogerCC Lin , linux-mtd@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: [PATCH 02/28] [v2] mtd: mtk: avoid warning in mtk_ecc_encode Date: Tue, 18 Oct 2016 00:05:31 +0200 Message-Id: <20161017220557.1688282-2-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20161017220342.1627073-1-arnd@arndb.de> References: <20161017220342.1627073-1-arnd@arndb.de> X-Provags-ID: V03:K0:i2YLrPLJHAF9xQ7UpSIk5QW14dMXCPX4XENib7C85fwlxzrRbK3 KMYbn21itDYgW1mgdbNUNKyC5HZZHnVsKQxrjYSZRFwNEanTFEadudQ+eHrqrpBTGnV9+QZ XxU6SMxgivffGEsOUIb4t/6MbJT9XNouE6EZ77E6qy0dEm18coXXfD/7iTckkHQ2n+PGfn/ ASi6ahKbbYDHPpNDAXlJg== X-UI-Out-Filterresults: notjunk:1;V01:K0:ueToa7PIf2E=:NFVEPyrfGopR3nNyPX6wig 9egVKkziPqjIqTkv3Hj0RM96htSxBuAvvRBTqxWQuuZsjW8GAjpaQQMQMKMIc/+IRBj3vjQDs pAdUY32Zdeo2CIynGnookebm87PZHKIqoMtw8jX2pulB//fyYnTcuOT0715KjLaZfv3NLm9RZ nrQjkNuijsjVAUSjvXeKGbTu4M0ddwa2Ea8bte0ancOpHJ4BwdCOWA0slueuZNz5NRlC9BqAc h3GOly2QaXZeGJM7SMCU6hLVPeYLOunCVeYi9yE99gs+4A+XpxADnSJQpeBHObm0NZreXrXc7 ErOBZAQLmhrCKz44hcbpZpav22tDtjV5Bhy/7oZyszUOTe+h6vXFS3IcFUtXlPtuGSYPues4n 5dLcXT0yCuLA7O1NGhvgN0/xcCswseQgBALmx2NBGwiW7l/nSAVh2Y2IKO0++cRZuPYnV3gMG /zPu/ZQqBxxSTlbF96L3qhqykHEjY8Al5scyvY3q1FwSFTP82vpB/Q3aUUJywEGNiDoYoeCnA OWFWLcxMyx1/sqBmCPjvR5/yvwPviGQEvyMw+7OMeVEhVoDmNEICEBpOvN8MNRUe6ZZ/cXejo SoNhqLBjI3tcdEDp/oHN6khohZuFLQIIzscP/zbzpJZAQp2UD7Piuu+WZX3s+yhTBOPFfsdh6 w1YOblaA+S9PPKXg6fPCdxlGtzz0XJ6YrLqvX656ORYazECBVAqEsGqAyhav5AAdfaow= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2493 Lines: 71 When building with -Wmaybe-uninitialized, gcc produces a silly false positive warning for the mtk_ecc_encode function: drivers/mtd/nand/mtk_ecc.c: In function 'mtk_ecc_encode': drivers/mtd/nand/mtk_ecc.c:402:15: error: 'val' may be used uninitialized in this function [-Werror=maybe-uninitialized] The function for some reason contains a double byte swap on big-endian builds to get the OOB data into the correct order again, and is written in a slightly confusing way. Using a simple memcpy32_fromio() to read the data simplifies it a lot so it becomes more readable and produces no warning. However, the output might not have 32-bit alignment, so we have to use another memcpy to avoid taking alignment faults or writing beyond the end of the array. Signed-off-by: Arnd Bergmann --- v2: move temporary buffer into struct mtk_ecc instead of having it on the stack, as suggested by Boris Brezillon --- drivers/mtd/nand/mtk_ecc.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/drivers/mtd/nand/mtk_ecc.c b/drivers/mtd/nand/mtk_ecc.c index d54f666..dbf2562 100644 --- a/drivers/mtd/nand/mtk_ecc.c +++ b/drivers/mtd/nand/mtk_ecc.c @@ -86,6 +86,8 @@ struct mtk_ecc { struct completion done; struct mutex lock; u32 sectors; + + u8 eccdata[112]; }; static inline void mtk_ecc_wait_idle(struct mtk_ecc *ecc, @@ -366,9 +368,8 @@ int mtk_ecc_encode(struct mtk_ecc *ecc, struct mtk_ecc_config *config, u8 *data, u32 bytes) { dma_addr_t addr; - u8 *p; - u32 len, i, val; - int ret = 0; + u32 len; + int ret; addr = dma_map_single(ecc->dev, data, bytes, DMA_TO_DEVICE); ret = dma_mapping_error(ecc->dev, addr); @@ -393,14 +394,12 @@ int mtk_ecc_encode(struct mtk_ecc *ecc, struct mtk_ecc_config *config, /* Program ECC bytes to OOB: per sector oob = FDM + ECC + SPARE */ len = (config->strength * ECC_PARITY_BITS + 7) >> 3; - p = data + bytes; - /* write the parity bytes generated by the ECC back to the OOB region */ - for (i = 0; i < len; i++) { - if ((i % 4) == 0) - val = readl(ecc->regs + ECC_ENCPAR(i / 4)); - p[i] = (val >> ((i % 4) * 8)) & 0xff; - } + /* write the parity bytes generated by the ECC back to temp buffer */ + __ioread32_copy(ecc->eccdata, ecc->regs + ECC_ENCPAR(0), round_up(len, 4)); + + /* copy into possibly unaligned OOB region with actual length */ + memcpy(data + bytes, ecc->eccdata, len); timeout: dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE); -- 2.9.0