Re: [PATCH for 5.2.y] mtd: cfi_cmdset_0002: Use chip_good() to retry in do_write_oneword()

From: Tokunori Ikegami <ikegami.t@gmail.com>
To: Greg KH <greg@kroah.com>
Cc: Sasha Levin <sashal@kernel.org>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Hauke Mehrtens <hauke@hauke-m.de>,
	stable@vger.kernel.org,
	Joakim Tjernlund <Joakim.Tjernlund@infinera.com>,
	Chris Packham <chris.packham@alliedtelesis.co.nz>,
	linux-mtd@lists.infradead.org, Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH for 5.2.y] mtd: cfi_cmdset_0002: Use chip_good() to retry in do_write_oneword()
Date: Wed, 18 Sep 2019 07:32:39 +0900	[thread overview]
Message-ID: <7c0113e0-d455-e3e6-86fc-45429be196fb@gmail.com> (raw)
In-Reply-To: <20190917181127.GD1570310@kroah.com>

On 2019/09/18 3:11, Greg KH wrote:
> On Wed, Sep 18, 2019 at 02:50:48AM +0900, Tokunori Ikegami wrote:
>> As reported by the OpenWRT team, write requests sometimes fail on some
>> platforms.
>> Currently to check the state chip_ready() is used correctly as described by
>> the flash memory S29GL256P11TFI01 datasheet.
>> Also chip_good() is used to check if the write is succeeded and it was
>> implemented by the commit fb4a90bfcd6d8 ("[MTD] CFI-0002 - Improve error
>> checking").
>> But actually the write failure is caused on some platforms and also it can
>> be fixed by using chip_good() to check the state and retry instead.
>> Also it seems that it is caused after repeated about 1,000 times to retry
>> the write one word with the reset command.
>> By using chip_good() to check the state to be done it can be reduced the
>> retry with reset.
>> It is depended on the actual flash chip behavior so the root cause is
>> unknown.
>>
>> Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
>> Cc: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
>> Cc: linux-mtd@lists.infradead.org
>> Cc: stable@vger.kernel.org
>> Reported-by: Fabio Bettoni <fbettoni@gmail.com>
>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>> Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
>> Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>
>> [vigneshr@ti.com: Fix a checkpatch warning]
>> Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
>> ---
>>   drivers/mtd/chips/cfi_cmdset_0002.c | 18 ++++++++++++------
>>   1 file changed, 12 insertions(+), 6 deletions(-)
>>   mode change 100644 => 100755 drivers/mtd/chips/cfi_cmdset_0002.c
> You changed the file to be executable???  That's not ok :(

Very sorry for this.
I missed it to fix to not be executable since it was changed to be 
executable on my local environment.
Anyway I will do fix it.

>
> Also, what is the git commit id of this patch in Linus's tree?  I can't
> seem to find it there.

Actually it has not been pulled in Linus's tree.
But it has been merged into 
git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next for 
v5.4-rc1 as the git commit id 37c673ade35c.
So I thought as that it is okay to send the patches for the stable trees.
But should I wait to be pulled the patch in Linus's tree at first?

>
> thanks,
>
> greg k-h

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