Messages in this thread | | | Date | Tue, 18 Oct 2016 07:19:48 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH 02/28] [v2] mtd: mtk: avoid warning in mtk_ecc_encode |
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On Tue, 18 Oct 2016 00:05:31 +0200 Arnd Bergmann <arnd@arndb.de> wrote:
> 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>
Jorge, RogerCC, can I have an Acked-by and/or Tested-by for this patch?
> --- > 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);
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