Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] mtd: mtk: avoid warning in mtk_ecc_encode | Date | Fri, 30 Sep 2016 18:33:02 +0200 |
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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 <arnd@arndb.de> --- drivers/mtd/nand/mtk_ecc.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/drivers/mtd/nand/mtk_ecc.c b/drivers/mtd/nand/mtk_ecc.c index d54f666417e1..237c83124a7d 100644 --- a/drivers/mtd/nand/mtk_ecc.c +++ b/drivers/mtd/nand/mtk_ecc.c @@ -366,9 +366,9 @@ 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; + u8 eccdata[112]; + int ret; addr = dma_map_single(ecc->dev, data, bytes, DMA_TO_DEVICE); ret = dma_mapping_error(ecc->dev, addr); @@ -393,14 +393,12 @@ 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(eccdata, ecc->regs + ECC_ENCPAR(0), round_up(len, 4)); + + /* copy into possibly unaligned OOB region with actual length */ + memcpy(data + bytes, eccdata, len); timeout: dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE); -- 2.9.0
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