From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann 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> References: <20161017220342.1627073-1-arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20161017220342.1627073-1-arnd-r2nGTMty4D4@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+glpam-linux-mediatek=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: Boris Brezillon Cc: Arnd Bergmann , Richard Weinberger , linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linus Torvalds , linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Matthias Brugger , Jorge Ramirez-Ortiz , Brian Norris , David Woodhouse , RogerCC Lin , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-mediatek@lists.infradead.org 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 From mboxrd@z Thu Jan 1 00:00:00 1970 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> In-Reply-To: <20161017220342.1627073-1-arnd@arndb.de> References: <20161017220342.1627073-1-arnd@arndb.de> List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Tue, 18 Oct 2016 00:05:31 +0200 Subject: [PATCH 02/28] [v2] mtd: mtk: avoid warning in mtk_ecc_encode In-Reply-To: <20161017220342.1627073-1-arnd@arndb.de> References: <20161017220342.1627073-1-arnd@arndb.de> Message-ID: <20161017220557.1688282-2-arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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