On 2018-05-26 14:16, Miquel Raynal wrote:
Hi Abhishek,
On Fri, 25 May 2018 17:51:41 +0530, Abhishek Sahu
<abs...@codeaurora.org> wrote:
The QCOM NAND controller layout is such that, the bad block byte
offset for last codeword will come to first byte in spare area.
"is the first spare byte"?
Currently, the raw read for last codeword is being done with
copy_last_cw function. It does following 2 things:
"It does the following:"
1. Read the last codeword bytes from NAND chip to NAND
controller internal HW buffer.
2. Copy all these bytes from HW buffer to actual buffer.
For bad block check, maximum two bytes are required so instead of
copying the complete bytes in step 2, only those bbm_size bytes
can be copied.
This patch does minor code reorganization for the same. After
this, copy_last_cw function won’t be required.
"This patch does minor code reorganization to just retrieve these two
bytes when checking for bad blocks, allowing to remove
copy_last_cw() now useless."
Thanks Miquel.
I will update all these.
Signed-off-by: Abhishek Sahu <abs...@codeaurora.org>
---
* Changes from v2:
1. Changed commit message and comments slightly
* Changes from v1:
NEW CHANGE
drivers/mtd/nand/raw/qcom_nandc.c | 66
+++++++++++++++------------------------
1 file changed, 25 insertions(+), 41 deletions(-)
diff --git a/drivers/mtd/nand/raw/qcom_nandc.c
b/drivers/mtd/nand/raw/qcom_nandc.c
index d693b5f..f72bc8a 100644
--- a/drivers/mtd/nand/raw/qcom_nandc.c
+++ b/drivers/mtd/nand/raw/qcom_nandc.c
@@ -1769,41 +1769,6 @@ static int read_page_ecc(struct qcom_nand_host
*host, u8 *data_buf,
return parse_read_errors(host, data_buf_start, oob_buf_start);
}
-/*
- * a helper that copies the last step/codeword of a page (containing
free oob)
- * into our local buffer
- */
-static int copy_last_cw(struct qcom_nand_host *host, int page)
-{
- struct nand_chip *chip = &host->chip;
- struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
- struct nand_ecc_ctrl *ecc = &chip->ecc;
- int size;
- int ret;
-
- clear_read_regs(nandc);
-
- size = host->use_ecc ? host->cw_data : host->cw_size;
-
- /* prepare a clean read buffer */
- memset(nandc->data_buffer, 0xff, size);
-
- set_address(host, host->cw_size * (ecc->steps - 1), page);
- update_rw_regs(host, 1, true);
-
- config_nand_single_cw_page_read(nandc);
-
- read_data_dma(nandc, FLASH_BUF_ACC, nandc->data_buffer, size, 0);
-
- ret = submit_descs(nandc);
- if (ret)
- dev_err(nandc->dev, "failed to copy last codeword\n");
-
- free_descs(nandc);
-
- return ret;
-}
-
/* implements ecc->read_page() */
static int qcom_nandc_read_page(struct mtd_info *mtd, struct
nand_chip *chip,
uint8_t *buf, int oob_required, int page)
@@ -2118,6 +2083,7 @@ static int qcom_nandc_block_bad(struct mtd_info
*mtd, loff_t ofs)
struct nand_ecc_ctrl *ecc = &chip->ecc;
int page, ret, bbpos, bad = 0;
u32 flash_status;
+ u8 *bbm_bytes_buf = chip->data_buf;
page = (int)(ofs >> chip->page_shift) & chip->pagemask;
@@ -2128,11 +2094,31 @@ static int qcom_nandc_block_bad(struct
mtd_info *mtd, loff_t ofs)
* that contains the BBM
*/
host->use_ecc = false;
+ bbpos = mtd->writesize - host->cw_size * (ecc->steps - 1);
Are we sure there is no layout with only 1 step?
All the layouts are such that, the BBM will come in
first byte of spare area.
For 4 bit ECC, the cw_size is 528 so for 2K page
2048 - 528 * 3 = 464
So for last CW, the 464 is BBM (i.e 2048th byte) in
full page.
clear_bam_transaction(nandc);
- ret = copy_last_cw(host, page);
- if (ret)
+ clear_read_regs(nandc);
+
+ set_address(host, host->cw_size * (ecc->steps - 1), page);
+ update_rw_regs(host, 1, true);
+
+ /*
+ * The last codeword data will be copied from NAND device to NAND
+ * controller internal HW buffer. Copy only required BBM size bytes
+ * from this HW buffer to bbm_bytes_buf which is present at
+ * bbpos offset.
+ */
+ nandc_set_read_loc(nandc, 0, bbpos, host->bbm_size, 1);
+ config_nand_single_cw_page_read(nandc);
+ read_data_dma(nandc, FLASH_BUF_ACC + bbpos, bbm_bytes_buf,
+ host->bbm_size, 0);
+
+ ret = submit_descs(nandc);
+ free_descs(nandc);
+ if (ret) {
+ dev_err(nandc->dev, "failed to copy bad block bytes\n");
goto err;
+ }
flash_status = le32_to_cpu(nandc->reg_read_buf[0]);
@@ -2141,12 +2127,10 @@ static int qcom_nandc_block_bad(struct
mtd_info *mtd, loff_t ofs)
goto err;
}
- bbpos = mtd->writesize - host->cw_size * (ecc->steps - 1);
-
- bad = nandc->data_buffer[bbpos] != 0xff;
+ bad = bbm_bytes_buf[0] != 0xff;
This is suspect as it still points to the beginning of the data buffer.
Can you please check you did not meant bbm_bytes_buf[bbpos]?
The main thing here is
nandc_set_read_loc(nandc, 0, bbpos, host->bbm_size, 1);
After reading one complete CW from NAND, the data will be still
in NAND HW buffer.
The above register tells that we need to read data from
bbpos of size host->bbm_size (which is 1 byte for 8 bus witdh
and 2 byte for 16 bus width) in bbm_bytes_buf.
So bbm_bytes_buf[0] will contain the BBM first byte.
and bbm_bytes_buf[1] will contain the BBM second byte.
Regards,
Abhishek
if (chip->options & NAND_BUSWIDTH_16)
- bad = bad || (nandc->data_buffer[bbpos + 1] != 0xff);
+ bad = bad || (bbm_bytes_buf[1] != 0xff);
err:
return bad;
}
Thanks,
Miquèl
