From: KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
To: Richard Weinberger <richard@nod.at>
Cc: David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mtd: nand: support for Toshiba BENAND (Built-in ECC NAND)
Date: Fri, 19 Jun 2015 23:46:41 +0900 [thread overview]
Message-ID: <55842B51.6000507@toshiba.co.jp> (raw)
In-Reply-To: <55802A44.6040708@nod.at>
> Please see my patches how to deal with that. Maybe you can find a better solution.
Thank you for your suggestion. I considered to use your submitted patch on BENAND
driver, but I believe reading twice the same page approach will affect read performance.
Additionally, BENAND does not support Disable ECC. So, I cannot use same approach.
I consider other solutions.
BENAND Read Status CMD (70h) can report Rewrite Recommend. BENAND also has extended
ECC Status CMD (7Ah). This can report number of bit error / sector data.
If I can use an extended ECC Status CMD (7Ah) in BENAND driver (nand_benand.c),
I suggest to implement it as the follows:
+++ b/drivers/mtd/nand/nand_benand.c
.....
+/* ECC Status Read Command */
+#define NAND_CMD_ECC_STATUS 0x7A
.....
+ chip->ecc.strength = 8;
.....
+ /* correctable */
+ else if (status & NAND_STATUS_RECOM_REWRT) {
+ if (chip->cmd_ctrl &&
+ IS_ENABLED(CONFIG_MTD_NAND_BENAND_ECC_STATUS)) {
+
+ /* Check Read ECC Status */
+ chip->cmd_ctrl(mtd, NAND_CMD_ECC_STATUS,
+ NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
+ ecc_status = chip->read_byte(mtd);
+ bitflips = ecc_status & 0xff;
+ mtd->ecc_stats.corrected += bitflips;
If above implementation cannot be acceptable, I would like to use "mtd->bitflip_threshold"
to inform number of bitflip, as the follows:
+ } else {
+ /*
+ * If can't use chip->cmd_ctrl,
+ * we can't get real number of bitflips.
+ * So, we set bitflips mtd->bitflip_threshold.
+ */
+ bitflips = mtd->bitflip_threshold;
+ mtd->ecc_stats.corrected += bitflips;
+ }
+ }
+
+ return bitflips;
+}
-- Yoshi
On 2015/06/16 22:53, Richard Weinberger wrote:
> Am 16.06.2015 um 15:33 schrieb KOBAYASHI Yoshitake:
>>>> + /* correctable */
>>>> + else if (status & NAND_STATUS_RECOM_REWRT) {
>>>> + pr_info("BENAND : Recommended to rewrite!\n");
>>>> + bitflips = chip->ecc.strength;
>>>
>>> In your case this might be okay, as you set strength to 1.
>>> Otherweise you'd have to report the real number of bitflips.
>>
>> I also thought it is okay in this case.
>> BENAND return corrected data to Host NAND Controller till uncorrectable status.
>> The current patch uses this Read Status command 70h to abstract BENAND Multi
>> bit ECC and Need to Rewrite judgement so BENAND would look like 1bit ECC device.
>
> The layers above MTD need to know how many bits got repaired.
> It seems like BENAND suffers from the same shortcomings than On-Die-ECC. ;-\
> Please see my patches how to deal with that. Maybe you can find a better solution.
>
> Thanks,
> //richard
>
>
>
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WARNING: multiple messages have this Message-ID (diff)
From: KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
To: Richard Weinberger <richard@nod.at>
Cc: "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
David Woodhouse <dwmw2@infradead.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] mtd: nand: support for Toshiba BENAND (Built-in ECC NAND)
Date: Fri, 19 Jun 2015 23:46:41 +0900 [thread overview]
Message-ID: <55842B51.6000507@toshiba.co.jp> (raw)
In-Reply-To: <55802A44.6040708@nod.at>
> Please see my patches how to deal with that. Maybe you can find a better solution.
Thank you for your suggestion. I considered to use your submitted patch on BENAND
driver, but I believe reading twice the same page approach will affect read performance.
Additionally, BENAND does not support Disable ECC. So, I cannot use same approach.
I consider other solutions.
BENAND Read Status CMD (70h) can report Rewrite Recommend. BENAND also has extended
ECC Status CMD (7Ah). This can report number of bit error / sector data.
If I can use an extended ECC Status CMD (7Ah) in BENAND driver (nand_benand.c),
I suggest to implement it as the follows:
+++ b/drivers/mtd/nand/nand_benand.c
.....
+/* ECC Status Read Command */
+#define NAND_CMD_ECC_STATUS 0x7A
.....
+ chip->ecc.strength = 8;
.....
+ /* correctable */
+ else if (status & NAND_STATUS_RECOM_REWRT) {
+ if (chip->cmd_ctrl &&
+ IS_ENABLED(CONFIG_MTD_NAND_BENAND_ECC_STATUS)) {
+
+ /* Check Read ECC Status */
+ chip->cmd_ctrl(mtd, NAND_CMD_ECC_STATUS,
+ NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
+ ecc_status = chip->read_byte(mtd);
+ bitflips = ecc_status & 0xff;
+ mtd->ecc_stats.corrected += bitflips;
If above implementation cannot be acceptable, I would like to use "mtd->bitflip_threshold"
to inform number of bitflip, as the follows:
+ } else {
+ /*
+ * If can't use chip->cmd_ctrl,
+ * we can't get real number of bitflips.
+ * So, we set bitflips mtd->bitflip_threshold.
+ */
+ bitflips = mtd->bitflip_threshold;
+ mtd->ecc_stats.corrected += bitflips;
+ }
+ }
+
+ return bitflips;
+}
-- Yoshi
On 2015/06/16 22:53, Richard Weinberger wrote:
> Am 16.06.2015 um 15:33 schrieb KOBAYASHI Yoshitake:
>>>> + /* correctable */
>>>> + else if (status & NAND_STATUS_RECOM_REWRT) {
>>>> + pr_info("BENAND : Recommended to rewrite!\n");
>>>> + bitflips = chip->ecc.strength;
>>>
>>> In your case this might be okay, as you set strength to 1.
>>> Otherweise you'd have to report the real number of bitflips.
>>
>> I also thought it is okay in this case.
>> BENAND return corrected data to Host NAND Controller till uncorrectable status.
>> The current patch uses this Read Status command 70h to abstract BENAND Multi
>> bit ECC and Need to Rewrite judgement so BENAND would look like 1bit ECC device.
>
> The layers above MTD need to know how many bits got repaired.
> It seems like BENAND suffers from the same shortcomings than On-Die-ECC. ;-\
> Please see my patches how to deal with that. Maybe you can find a better solution.
>
> Thanks,
> //richard
>
>
>
next prev parent reply other threads:[~2015-06-19 14:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-11 16:00 [PATCH v2] mtd: nand: support for Toshiba BENAND (Built-in ECC NAND) KOBAYASHI Yoshitake
2015-06-12 8:11 ` Paul Bolle
2015-06-12 8:11 ` Paul Bolle
2015-06-16 13:37 ` KOBAYASHI Yoshitake
2015-06-16 13:37 ` KOBAYASHI Yoshitake
2015-06-12 9:49 ` Richard Weinberger
2015-06-12 9:49 ` Richard Weinberger
2015-06-16 13:33 ` KOBAYASHI Yoshitake
2015-06-16 13:33 ` KOBAYASHI Yoshitake
2015-06-16 13:53 ` Richard Weinberger
2015-06-16 13:53 ` Richard Weinberger
2015-06-19 14:46 ` KOBAYASHI Yoshitake [this message]
2015-06-19 14:46 ` KOBAYASHI Yoshitake
2015-07-24 17:42 ` [PATCH REPOST v3] mtd: nand " KOBAYASHI Yoshitake
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