linux-kernel - Re: [PATCH] mtd: spi-nor: stop printing superfluous debug info

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Message-ID: <CAAQoYR=ZAEVeoCwkRmky2CHVeKGX55JijM8Q6D5msz_5iW+jtw@mail.gmail.com>
Date:   Tue, 28 Nov 2023 17:24:42 +0800
From:   liao jaime <jaimeliao.tw@...il.com>
To:     Michael Walle <michael@...le.cc>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Tudor Ambarus <tudor.ambarus@...aro.org>,
        jaimeliao@...c.com.tw, pratyush@...nel.org, richard@....at,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: spi-nor: stop printing superfluous debug info

Hi


>
> Hi,
>
> >> > The mtd data can be obtain with the mtd ioctls and the SPI NOR
> >> > flash name can be determined interrogating the sysfs entries.
> >> > Stop polluting the kernel log.
> >> >
> >> > Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
> >> >
> >> > ---
> >> >  drivers/mtd/spi-nor/core.c | 19 -------------------
> >> >  1 file changed, 19 deletions(-)
> >> >
> >> > diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> >> > index 25a64c65717d..6de76fd009d1 100644
> >> > --- a/drivers/mtd/spi-nor/core.c
> >> > +++ b/drivers/mtd/spi-nor/core.c
> >> > @@ -3517,25 +3517,6 @@ int spi_nor_scan(struct spi_nor *nor, const char > *name,
> >> >    /* No mtd_info fields should be used up to this point. */
> >> >    spi_nor_set_mtd_info(nor);
> >> >
> >> > -  dev_info(dev, "%s (%lld Kbytes)\n", info->name,
> >> > -                  (long long)mtd->size >> 10);
> >>
> >> I'd lower this to dev_dbg() and print the jedec id. It might come in
> >> handy for a quick glance during bootup if debug is enabled.
> >
> > Ack. Although, your boot time will almost be unaffected if you don't
> > print the info messages to the console. What takes the most time is not
> > writing to the kernel buffer, it's to display the lines on a serial
> > console, and dev_info() are by default discarded, you need to select a
> > lower log level manually, and if you do that it means you're not
> > looking for quick boot times but rather more for additional
> > information.
>
> Also with recent (or planned, dunno the current state) printk won't wait
> anymore for the slowest console. I really don't have a strong opinion,
> either dev_info(jedec_id) or dev_dbg(jedec_id). Whatever Tudor prefers.
>
> >> > -  dev_dbg(dev,
> >> > -          "mtd .name = %s, .size = 0x%llx (%lldMiB), "
> >> > -          ".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d\n",
> >> > -          mtd->name, (long long)mtd->size, (long long)(mtd->size >> 20),
> >> > -          mtd->erasesize, mtd->erasesize / 1024, mtd->numeraseregions);
> >> > -
> >> > -  if (mtd->numeraseregions)
> >> > -          for (i = 0; i < mtd->numeraseregions; i++)
> >> > -                  dev_dbg(dev,
> >> > -                          "mtd.eraseregions[%d] = { .offset = 0x%llx, "
> >> > -                          ".erasesize = 0x%.8x (%uKiB), "
> >> > -                          ".numblocks = %d }\n",
> >> > -                          i, (long long)mtd->eraseregions[i].offset,
> >> > -                          mtd->eraseregions[i].erasesize,
> >> > -                          mtd->eraseregions[i].erasesize / 1024,
> >> > -                          mtd->eraseregions[i].numblocks);
> >> >    return 0;
> >>
> >> Part of this is already available through the spi-nor debugfs,
> >> although not
> >> the actual mtd properties. These I think, should go into the mtdcore
> >> itself if really needed. Either through dev_dbg() or debugfs.
> >
> > Maybe we don't need this at all, as long as one message remains about
> > the JEDEC ID, but keep in mind that spi-nors are commonly storing the
> > rootfs and if your spi-nor does not boot you don't have a userspace yet
> > and all the debugfs entries are purely useless.
>
> Good point.
>
> Just curious, do you know any boards which has the rootfs writable on
> the spi-nor flash?
I am also interested.

>
> -michael
>

Thanks
Jaime