linux-kernel - Re: [PATCH v4 03/11] mtd: spi-nor: core: Use auto-detection only once

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Message-ID: <20220427052000.xmctvowj4kuc727d@ti.com>
Date:   Wed, 27 Apr 2022 10:50:00 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     <Tudor.Ambarus@...rochip.com>
CC:     <michael@...le.cc>, <miquel.raynal@...tlin.com>, <richard@....at>,
        <vigneshr@...com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <Takahiro.Kuwano@...ineon.com>
Subject: Re: [PATCH v4 03/11] mtd: spi-nor: core: Use auto-detection only once

On 21/04/22 01:41PM, Tudor.Ambarus@...rochip.com wrote:
> On 4/21/22 16:16, Pratyush Yadav wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On 21/04/22 07:18AM, Tudor.Ambarus@...rochip.com wrote:
> >> Hi, Pratyush,
> >>
> >> I forgot to remove few checks, would you please remove them when applying?
> >> See below.
> >>
> >> On 4/20/22 13:34, Tudor Ambarus wrote:
> >>> In case spi_nor_match_name() returned NULL, the auto detection was
> >>> issued twice. There's no reason to try to detect the same chip twice,
> >>> do the auto detection only once.
> >>>
> >>> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> >>> Reviewed-by: Michael Walle <michael@...le.cc>
> >>> ---
> >>>  drivers/mtd/spi-nor/core.c | 13 ++++++++-----
> >>>  1 file changed, 8 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> >>> index b9cc8bbf1f62..b55d922d46dd 100644
> >>> --- a/drivers/mtd/spi-nor/core.c
> >>> +++ b/drivers/mtd/spi-nor/core.c
> >>> @@ -2896,13 +2896,14 @@ static const struct flash_info *spi_nor_get_flash_info(struct spi_nor *nor,
> >>>  {
> >>>     const struct flash_info *info = NULL;
> >>>
> >>> -   if (name)
> >>> +   if (name) {
> >>>             info = spi_nor_match_name(nor, name);
> >>> +           if (IS_ERR(info))
> >>> +                   return info;
> >>
> >> As Michael suggested spi_nor_match_name() returns NULL or valid entry, so this
> >> check is not necessary, let's remove them.
> >>
> >>> +   }
> >>>     /* Try to auto-detect if chip name wasn't specified or not found */
> >>>     if (!info)
> >>> -           info = spi_nor_read_id(nor);
> >>> -   if (IS_ERR_OR_NULL(info))
> >>> -           return ERR_PTR(-ENOENT);
> >>> +           return spi_nor_read_id(nor);
> >>>
> >>>     /*
> >>>      * If caller has specified name of flash model that can normally be
> >>> @@ -2994,7 +2995,9 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
> >>>             return -ENOMEM;
> >>>
> >>>     info = spi_nor_get_flash_info(nor, name);
> >>> -   if (IS_ERR(info))
> >>> +   if (!info)
> >>> +           return -ENOENT;
> >>
> >> also according to Michael, this change is not needed as spi_nor_get_flash_info() can't
> >> return NULL. Here we can keep the code as it was. Let me know if you want me to respin.
> > 
> > TBH I don't think a NULL check here hurts much since the behaviour might
> > change later, and error paths don't get exercised as often. But I have
> 
> I agree, but at the same time we're introducing checks gratuitously. Since
> Michael cared about it, it's fine that we removed it. I don't care too much
> about it.
> 
> > made both changes when applying. You can double-check at [0] if you
> > want.> 
> > [0] https://github.com/prati0100/linux-0day/commit/67d913746833ee54bf4c661040f3ef13657dffd8
> 
> looks good.
> 
> btw: I think this patch
> https://github.com/prati0100/linux-0day/commit/b45bbff85d49529f8daff83c341a292f6c6492ca
> may introduce a regression on some atmel chips. Let me try it please.

Did you get a chance to try this out? If it works fine, I would like to 
apply it.

> > 
> >>
> >>> +   else if (IS_ERR(info))
> >>>             return PTR_ERR(info);
> >>>
> >>>     nor->info = info;
> >>
> > 
> > --
> > Regards,
> > Pratyush Yadav
> > Texas Instruments Inc.
> 

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.