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

From: Greg KH <greg@kroah.com>
To: Tokunori Ikegami <ikegami.t@gmail.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 07:52:46 +0200	[thread overview]
Message-ID: <20190918055246.GC1830105@kroah.com> (raw)
In-Reply-To: <7c0113e0-d455-e3e6-86fc-45429be196fb@gmail.com>

On Wed, Sep 18, 2019 at 07:32:39AM +0900, Tokunori Ikegami wrote:
> 
> 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.

Please do, we can not take these patches as-is at all.

> > 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?

Yes, you have to wait, please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

thanks,

greg k-h

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