Re: [PATCH 1/1] mtd/intel-spi: Support cmdline-based partition

[ron minnich <rminnich@gmail.com>]

I'm fine with that. I have not had a chance to test it but it should be fine.

On Mon, Apr 27, 2020 at 7:41 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>
> Hi Ron,
>
> Boris Brezillon <boris.brezillon@collabora.com> wrote on Mon, 27 Apr
> 2020 11:49:54 +0200:
>
> > On Mon, 27 Apr 2020 11:16:23 +0200
> > Boris Brezillon <boris.brezillon@collabora.com> wrote:
> >
> > > Hi all,
> > >
> > > On Wed, 1 Apr 2020 09:41:48 +0200
> > > Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> > >
> > > > Hi ron,
> > > >
> > > > ron minnich <rminnich@gmail.com> wrote on Mon, 30 Mar 2020 08:53:22
> > > > -0700:
> > > >
> > > > > On Mon, Mar 30, 2020 at 12:27 AM Miquel Raynal
> > > > > <miquel.raynal@bootlin.com> wrote:
> > > > >
> > > > > > Would it be hard to support an extra ':' after the MTD device name?
> > > > > > This way would would allow anything inside the optional '(' ')' but
> > > > > > would keep the trailing ':'.
> > > > > >
> > > > > > toTay:
> > > > > >         mtdparts=name:part1,part2
> > > > > >
> > > > > > So:
> > > > > >         mtdparts=(0000:00:1f.5):25165824(BIOS),-(squashfs)
> > > > >
> > > > >
> > > > > I thought about that ':' too. It does add a bit more to the code, and
> > > > > a bit more in the way of error cases. I always worry, when code is
> > > > > going into flash,
> > > > > about errors where something looks close to right but is wrong. (says
> > > > > the person who just typed it instead of is a few times :-)
> > > > >
> > > > > What if we did this:
> > > > > mtdparts=[0000:00:1f.5]25165824(BIOS),-(squashfs)
> > > > >
> > > > > Is the "]" 'enough different' that we do not need the ':'?
> > > > >
> > > > > I kind of like the [] better anyway as it makes the mtdid stand out a
> > > > > bit more from the part names? But is it enough that we don't need the
> > > > > ':'? Would you still prefer the () as opposed to the []?
> > > >
> > > > I like the [] as well, maybe more than () because at least it does not
> > > > conflict with the partition names. But I really prefer keeping the : if
> > > > the code is still readable.
> > > >
> > > > It is much easier to explain to people : "if you have a : in the name,
> > > > enclose it with []".
> > >
> > > Sorry to chime in so late in the discussion, but I wonder if any of
> > > that is necessary. Can't we just split the string per device (split
> > > strings every time we see a ';'), and then find the last ':' in each of
> > > those strings and consider everything before that last ':' to be the MTD
> > > name. That should work even if the MTD name contains one or more ':'.
> > >
> > > Don't get me wrong, I'm perfectly fine with intel enclosing the PCI
> > > address in [] to make it clearer, but I see that other drivers use ':'
> > > in their MTD device names (the atmel raw NAND controller driver to name
> > > one), so I think it'd be good to make the mtd part parsing robust to
> > > this use case.
> >
> > I just gave it a try and the following patch should solve the problem
> > (only compile-tested). As I said previously, it doesn't prevent you from
> > enclosing the PCI address in [] if you think it's clearer, but I think
> > the problem should be addressed in the cmdline parser anyway.
> >
> > --->8---
> > From 08b30597dd73efd9c4c8d1906ab02a9540875419 Mon Sep 17 00:00:00 2001
> > From: Boris Brezillon <boris.brezillon@collabora.com>
> > Date: Mon, 27 Apr 2020 11:44:50 +0200
> > Subject: [PATCH] mtd: parser: cmdline: Support MTD names containing one or
> >  more colons
> >
> > Looks like some drivers define MTD names with a colon in it, thus
> > making mtdpart= parsing impossible. Let's fix the parser to gracefully
> > handle that case: the last ':' in a partition definition sequence is
> > considered instead of the first one.
> >
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > ---
> >  drivers/mtd/parsers/cmdlinepart.c | 23 ++++++++++++++++++++---
> >  1 file changed, 20 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mtd/parsers/cmdlinepart.c b/drivers/mtd/parsers/cmdlinepart.c
> > index c86f2db8c882..0625b25620ca 100644
> > --- a/drivers/mtd/parsers/cmdlinepart.c
> > +++ b/drivers/mtd/parsers/cmdlinepart.c
> > @@ -218,12 +218,29 @@ static int mtdpart_setup_real(char *s)
> >               struct cmdline_mtd_partition *this_mtd;
> >               struct mtd_partition *parts;
> >               int mtd_id_len, num_parts;
> > -             char *p, *mtd_id;
> > +             char *p, *mtd_id, *semicol;
> > +
> > +             /*
> > +              * Replace the first ';' by a NULL char so strrchr can work
> > +              * properly.
> > +              */
> > +             semicol = strchr(s, ';');
> > +             if (semicol)
> > +                     *semicol = '\0';
> >
> >               mtd_id = s;
> >
> > -             /* fetch <mtd-id> */
> > -             p = strchr(s, ':');
> > +             /*
> > +              * fetch <mtd-id>. We use strrchr to ignore all ':' that could
> > +              * be present in the MTD name, only the last one is interpreted
> > +              * as an <mtd-id>/<part-definition> separator.
> > +              */
> > +             p = strrchr(s, ':');
> > +
> > +             /* Restore the ';' now. */
> > +             if (semicol)
> > +                     *semicol = ';';
> > +
> >               if (!p) {
> >                       pr_err("no mtd-id\n");
> >                       return -EINVAL;
>
> This is also the approach I like the most. It avoids modifying the
> syntax on the cmdline (no change in Bootloaders needed) and we don't
> have to change the parser of a driver every time a colon is in the
> name.
>
> I would like to drop "mtd: parsers: support '[]' fir ud ub mtdparts" as
> welle as "mtd: spi-nor: controllers: intel-spi: Add support for command
> line partitions", what do you think?
>
>
> Thanks,
> Miquèl

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/