Patchwork mtd: gpmi: Always report ECC stats and return max_bitflips

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Submitter Zach Sadecki
Date Dec. 3, 2012, 7:48 p.m.
Message ID <50BD01F8.3040003@itwatchdogs.com>
Download mbox | patch
Permalink /patch/203426/
State New
Headers show

Comments

Zach Sadecki - Dec. 3, 2012, 7:48 p.m.
Always report corrected and failed ECC stats back up to the MTD layer.  Also
return max_bitflips from read_page() as is expected from NAND drivers now.

Signed-off-by: Zach Sadecki <zsadecki@itwatchdogs.com>
---
   drivers/mtd/nand/gpmi-nand/gpmi-nand.c |   27 ++++++++-------------------
   1 file changed, 8 insertions(+), 19 deletions(-)
Huang Shijie - Dec. 4, 2012, 3:34 a.m.
于 2012年12月04日 03:48, Zach Sadecki 写道:
> Always report corrected and failed ECC stats back up to the MTD layer. 
> Also
> return max_bitflips from read_page() as is expected from NAND drivers 
> now.
>
> Signed-off-by: Zach Sadecki <zsadecki@itwatchdogs.com>
> ---
> drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 27 ++++++++-------------------
> 1 file changed, 8 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c 
> b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> index d79696b..fe10c53 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> @@ -914,8 +914,7 @@ static int gpmi_ecc_read_page(struct mtd_info 
> *mtd, struct nand_chip *chip,
> dma_addr_t auxiliary_phys;
> unsigned int i;
> unsigned char *status;
> - unsigned int failed;
> - unsigned int corrected;
> + unsigned int max_bitflips = 0;
> int ret;
> pr_debug("page number is : %d\n", page);
> @@ -939,35 +938,25 @@ static int gpmi_ecc_read_page(struct mtd_info 
> *mtd, struct nand_chip *chip,
> payload_virt, payload_phys);
> if (ret) {
> pr_err("Error in ECC-based read: %d\n", ret);
> - goto exit_nfc;
> + return ret;
> }
> /* handle the block mark swapping */
> block_mark_swapping(this, payload_virt, auxiliary_virt);
> /* Loop over status bytes, accumulating ECC status. */
> - failed = 0;
> - corrected = 0;
> - status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
> + status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
> for (i = 0; i < nfc_geo->ecc_chunk_count; i++, status++) {
> if ((*status == STATUS_GOOD) || (*status == STATUS_ERASED))
> continue;
> if (*status == STATUS_UNCORRECTABLE) {
> - failed++;
> + mtd->ecc_stats.failed++;
> continue;
> }
> - corrected += *status;
> - }
> -
> - /*
> - * Propagate ECC status to the owning MTD only when failed or
> - * corrected times nearly reaches our ECC correction threshold.
> - */
> - if (failed || corrected >= (nfc_geo->ecc_strength - 1)) {
> - mtd->ecc_stats.failed += failed;
> - mtd->ecc_stats.corrected += corrected;
> + mtd->ecc_stats.corrected += *status;
> + max_bitflips = max_t(unsigned int, max_bitflips, *status);

Does the max_bitflips stand for the whole page's bitfips ? or just the 
bitfips of one part of the page?
The gpmi driver splits a page into several parts when it does the ECC.

thanks
Huang Shijie


> }
> if (oob_required) {
> @@ -989,8 +978,8 @@ static int gpmi_ecc_read_page(struct mtd_info 
> *mtd, struct nand_chip *chip,
> this->payload_virt, this->payload_phys,
> nfc_geo->payload_size,
> payload_virt, payload_phys);
> -exit_nfc:
> - return ret;
> +
> + return max_bitflips;
> }
> static int gpmi_ecc_write_page(struct mtd_info *mtd, struct nand_chip 
> *chip,
Zach Sadecki - Dec. 4, 2012, 2:40 p.m.
On 12/03/2012 09:34 PM, Huang Shijie wrote:
> 于 2012年12月04日 03:48, Zach Sadecki 写道:
>> Always report corrected and failed ECC stats back up to the MTD 
>> layer. Also
>> return max_bitflips from read_page() as is expected from NAND drivers 
>> now.
>>
>> Signed-off-by: Zach Sadecki <zsadecki@itwatchdogs.com>
>> ---
>> drivers/mtd/nand/gpmi-nand/gpmi-nand.c | 27 ++++++++-------------------
>> 1 file changed, 8 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c 
>> b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> index d79696b..fe10c53 100644
>> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> @@ -914,8 +914,7 @@ static int gpmi_ecc_read_page(struct mtd_info 
>> *mtd, struct nand_chip *chip,
>> dma_addr_t auxiliary_phys;
>> unsigned int i;
>> unsigned char *status;
>> - unsigned int failed;
>> - unsigned int corrected;
>> + unsigned int max_bitflips = 0;
>> int ret;
>> pr_debug("page number is : %d\n", page);
>> @@ -939,35 +938,25 @@ static int gpmi_ecc_read_page(struct mtd_info 
>> *mtd, struct nand_chip *chip,
>> payload_virt, payload_phys);
>> if (ret) {
>> pr_err("Error in ECC-based read: %d\n", ret);
>> - goto exit_nfc;
>> + return ret;
>> }
>> /* handle the block mark swapping */
>> block_mark_swapping(this, payload_virt, auxiliary_virt);
>> /* Loop over status bytes, accumulating ECC status. */
>> - failed = 0;
>> - corrected = 0;
>> - status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
>> + status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
>> for (i = 0; i < nfc_geo->ecc_chunk_count; i++, status++) {
>> if ((*status == STATUS_GOOD) || (*status == STATUS_ERASED))
>> continue;
>> if (*status == STATUS_UNCORRECTABLE) {
>> - failed++;
>> + mtd->ecc_stats.failed++;
>> continue;
>> }
>> - corrected += *status;
>> - }
>> -
>> - /*
>> - * Propagate ECC status to the owning MTD only when failed or
>> - * corrected times nearly reaches our ECC correction threshold.
>> - */
>> - if (failed || corrected >= (nfc_geo->ecc_strength - 1)) {
>> - mtd->ecc_stats.failed += failed;
>> - mtd->ecc_stats.corrected += corrected;
>> + mtd->ecc_stats.corrected += *status;
>> + max_bitflips = max_t(unsigned int, max_bitflips, *status);
>
> Does the max_bitflips stand for the whole page's bitfips ? or just the 
> bitfips of one part of the page?
> The gpmi driver splits a page into several parts when it does the ECC.
>
> thanks
> Huang Shijie
>
max_bitflips represents the maximum number of bitflips per ECC corrected 
region in a page.  The MTD layer needs it to compare to 
bitflip_threshold to know when to return -EUCLEAN to upper layers (like 
UBI) so a nearly corrupt page can be copied elsewhere.  This is pretty 
much identical to the way other drivers do this as I copied it from 
those.  Here's where it was added in the other drivers: 
http://git.infradead.org/linux-mtd.git/commit/3f91e94f7f511de74c0d2abe08672ccdbdd1961c 


Zach
>
>> }
>> if (oob_required) {
>> @@ -989,8 +978,8 @@ static int gpmi_ecc_read_page(struct mtd_info 
>> *mtd, struct nand_chip *chip,
>> this->payload_virt, this->payload_phys,
>> nfc_geo->payload_size,
>> payload_virt, payload_phys);
>> -exit_nfc:
>> - return ret;
>> +
>> + return max_bitflips;
>> }
>> static int gpmi_ecc_write_page(struct mtd_info *mtd, struct nand_chip 
>> *chip,
>
>
Huang Shijie - Dec. 5, 2012, 3:04 a.m.
于 2012年12月04日 22:40, Zach Sadecki 写道:
> max_bitflips represents the maximum number of bitflips per ECC 
> corrected region in a page. 
got it.

I also tested this patch in the mx6q-arm2 board. it runned well.

thanks.

Acked-by: Huang Shijie <b32955@freescale.com>


Huang Shijie
Artem Bityutskiy - Dec. 10, 2012, 1:44 p.m.
On Mon, 2012-12-03 at 13:48 -0600, Zach Sadecki wrote:
> Always report corrected and failed ECC stats back up to the MTD layer.  Also
> return max_bitflips from read_page() as is expected from NAND drivers now.
> 
> Signed-off-by: Zach Sadecki <zsadecki@itwatchdogs.com>

Could you please send a version which applies cleanly to the l2-mtd.git
tree? Thanks!

git://git.infradead.org/users/dedekind/l2-mtd.git

Patch

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
index d79696b..fe10c53 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -914,8 +914,7 @@  static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
   	dma_addr_t    auxiliary_phys;
   	unsigned int  i;
   	unsigned char *status;
-	unsigned int  failed;
-	unsigned int  corrected;
+	unsigned int  max_bitflips = 0;
   	int           ret;
   
   	pr_debug("page number is : %d\n", page);
@@ -939,35 +938,25 @@  static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
   			payload_virt, payload_phys);
   	if (ret) {
   		pr_err("Error in ECC-based read: %d\n", ret);
-		goto exit_nfc;
+		return ret;
   	}
   
   	/* handle the block mark swapping */
   	block_mark_swapping(this, payload_virt, auxiliary_virt);
   
   	/* Loop over status bytes, accumulating ECC status. */
-	failed		= 0;
-	corrected	= 0;
-	status		= auxiliary_virt + nfc_geo->auxiliary_status_offset;
+	status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
   
   	for (i = 0; i < nfc_geo->ecc_chunk_count; i++, status++) {
   		if ((*status == STATUS_GOOD) || (*status == STATUS_ERASED))
   			continue;
   
   		if (*status == STATUS_UNCORRECTABLE) {
-			failed++;
+			mtd->ecc_stats.failed++;
   			continue;
   		}
-		corrected += *status;
-	}
-
-	/*
-	 * Propagate ECC status to the owning MTD only when failed or
-	 * corrected times nearly reaches our ECC correction threshold.
-	 */
-	if (failed || corrected >= (nfc_geo->ecc_strength - 1)) {
-		mtd->ecc_stats.failed    += failed;
-		mtd->ecc_stats.corrected += corrected;
+		mtd->ecc_stats.corrected += *status;
+		max_bitflips = max_t(unsigned int, max_bitflips, *status);
   	}
   
   	if (oob_required) {
@@ -989,8 +978,8 @@  static int gpmi_ecc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
   			this->payload_virt, this->payload_phys,
   			nfc_geo->payload_size,
   			payload_virt, payload_phys);
-exit_nfc:
-	return ret;
+
+	return max_bitflips;
   }
   
   static int gpmi_ecc_write_page(struct mtd_info *mtd, struct nand_chip *chip,