mtd: mtk: avoid warning in mtk_ecc_encode (8ff0513b) · Commits · 戴 / test

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> Tested-by:

RogerCC Lin <rogercc.lin@mediatek.com> Signed-off-by:

Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/mtk_ecc.c

+9 −10

Original line number	Diff line number	Diff line
		@@ -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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