From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933751AbcI3Qfd (ORCPT ); Fri, 30 Sep 2016 12:35:33 -0400 Received: from mout.kundenserver.de ([212.227.126.135]:53788 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933708AbcI3QfZ (ORCPT ); Fri, 30 Sep 2016 12:35:25 -0400 From: Arnd Bergmann To: Boris Brezillon , David Woodhouse , Brian Norris Cc: Arnd Bergmann , Richard Weinberger , Matthias Brugger , linux-mtd@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] mtd: mtk: avoid warning in mtk_ecc_encode Date: Fri, 30 Sep 2016 18:33:02 +0200 Message-Id: <20160930163429.380785-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 X-Provags-ID: V03:K0:/yOpLk+0G12yTpm2us2OcE/EJUXmeZGurVSm0GR2JsvjB4jvLnD O6QjRuNZez6PjBfy0GCnvzRXylOZSRGiuiubhueNzFFVB9pD7Ji38vrPZ9MSWNq0nxIjul2 HSGGZtQS+R3UMuIlKgvmXcj86uRBF/xM4nFyQcWyIbbsP8E2YUYUTNTJhgJzTGJNkjSdqF6 0C+YIk8Wl/JHXziCt7P9g== X-UI-Out-Filterresults: notjunk:1;V01:K0:Knin6uPFf2g=:Y1zX6YrJdnNlNFYbQjJuXE v6fiyC1Pwvczha3Ev4AXXOTrodGwB4zsTe4MHA9DMp6Z+cZgMOTack7R+zYP/5rwGRXVriX0d ZHPld7jYmiJjFEnN/V6Ku13iyv66Ui+0xTSj4fK2dUa9BhiUqzR+Ck72ywBwBSn73WOqzoUzV qRxsWPvcJBnZtRWELrxFUUJR0/SE/SNnhFE2/7L1tb2yDigEKjJ3xqonEk6q/oYS4F+nL3htF BFKhFOYw6YZvHcTXHtNQb1Ih5X2GeQx2/CUAdd/orMXkdj8qxfKW0dvnCxAl0N0JpQFX6Xmiz e19IkFrb9+eTbrcV86Shygbn8z1l0CIZCvrIu5iXCOtb+9EKduk2ZxHY+6YtswlPk6yCiuqik nrhc8P8/gN24uk9wXHvdiRrwtvc5YnuG1Y9Gv6cIOIJbSyUoZSOTlBL+1aLiFeU+Kn1RYztWA R8cYhMSeOH15Ec2+8Vild2mMpgIL06gEOTZ0MpAj+J88NXzva6tE0UCveqpNfTLZ1nSBZxpSV KkXGDfEhTbVuEuKWqi7xeSvHiUid+/ZIP3M4H4Hcx1LTQP1tORUvFZRyibOXhB9VNmKIOnJoE vqCTf+KYJqX40LP9+GZd/NVF7f6Aq9+JwtjfPNTeTM4yKKGTY+FEMlsNTVlFr6X7MX8BTjoyK Y/zyhSMeH+yZCgSREWIK8Ok2dZD3/OsgBVTy7iReazbIAhP76nD2W7hTTdpAa7a5RDfA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 --- 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