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Commit 1a3fe590 authored by Krishna Konda's avatar Krishna Konda Committed by Gerrit - the friendly Code Review server
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mtd: msm_qpic_nand: fix bit flipped data in erased pages 



Some filesystems like UBIFS might expect the data read from an erased
page be all 0xff. In case there is a bit flip in the device then the
data in that page would not all be 0xff's.

While the page would have been identified as an erased page and there
wont be an other errors generated, the data still needs to be fixed,
which is beind done here.

Change-Id: Idd30a2bf50f5782691973df804711fb1c0719f6a
Signed-off-by: default avatarKrishna Konda <kkonda@codeaurora.org>
parent 3b74bf1e

drivers/mtd/devices/msm_qpic_nand.c

+39 −0
Original line number Diff line number Diff line
@@ -1618,6 +1618,7 @@ static int msm_nand_read_oob(struct mtd_info *mtd, loff_t from, 
	struct sps_iovec *iovec;

	struct sps_iovec iovec_temp;

	bool erased_page;

	uint64_t fix_data_in_pages = 0;



	/*

	 * The following 6 commands will be sent only once for the first
@@ -1839,6 +1840,20 @@ static int msm_nand_read_oob(struct mtd_info *mtd, loff_t from, 
				}

			}

		}



		if (rawerr && !pageerr && erased_page) {

			/*

			 * This means an erased page had bit flips and now

			 * those bit-flips need to be cleared in the data

			 * being sent to upper layers. This will keep track

			 * of those pages and at the end, the data will be

			 * fixed before this function returns.

			 * Note that a whole page worth of data will be fixed

			 * and this will only handle about 64 pages being read

			 * at a time i.e. one erase block worth of pages.

			 */

			fix_data_in_pages |= BIT(rw_params.page_count);

		}

		/* check for correctable errors */

		if (!rawerr) {

			for (n = rw_params.start_sector; n < cwperpage; n++) {
@@ -1898,6 +1913,30 @@ free_dma: 
	if (ops->datbuf)

		dma_unmap_page(chip->dev, rw_params.data_dma_addr,

				 ops->len, DMA_BIDIRECTIONAL);

	/*

	 * If there were any erased pages detected with ECC errors, then

	 * it is most likely that the data is not all 0xff. So memset that

	 * page to all 0xff.

	 */

	while (fix_data_in_pages) {

		int temp_page = 0, oobsize = rw_params.cwperpage << 2;

		int count = 0, offset = 0;



		temp_page = fix_data_in_pages & BIT_MASK(0);

		fix_data_in_pages = fix_data_in_pages >> 1;

		count++;



		if (!temp_page)

			continue;



		offset = (count - 1) * mtd->writesize;

		if (ops->datbuf)

			memset((ops->datbuf + offset), 0xff, mtd->writesize);



		offset = (count - 1) * oobsize;

		if (ops->oobbuf)

			memset(ops->oobbuf + offset, 0xff, oobsize);

	}

validate_mtd_params_failed:

	if (ops->mode != MTD_OPS_RAW)

		ops->retlen = mtd->writesize * pages_read;