[U-Boot] [PATCH v7 05/13] cmd: mtdparts: remove mandatory 'mtdparts=' prefix

[Miquel Raynal]

Hi Stefan,

Stefan Roese <sr at denx.de> wrote on Sat, 1 Sep 2018 10:50:54 +0200:

> On 31.08.2018 16:57, Miquel Raynal wrote:
> > All U-Boot users must define the mtdparts environment variable with:
> > setenv mtdparts mtdparts=...  
> > > While this may ease the partition declaration job to be passed to  
> > Linux, this is a pure software limitation and forcing this prefix is a
> > complete non-sense. Let the user to declare manually the mtdparts
> > variable without the prefix.  
> > > Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>  
> > Acked-by: Jagan Teki <jagan at openedev.com>
> > ---
> >   cmd/mtdparts.c | 17 ++++++-----------
> >   1 file changed, 6 insertions(+), 11 deletions(-)  
> > > diff --git a/cmd/mtdparts.c b/cmd/mtdparts.c  
> > index 2e547894c6..f7ed1a0779 100644
> > --- a/cmd/mtdparts.c
> > +++ b/cmd/mtdparts.c
> > @@ -44,7 +44,7 @@
> >    *
> >    * 'mtdparts' - partition list
> >    *
> > - * mtdparts=mtdparts=<mtd-def>[;<mtd-def>...]
> > + * mtdparts=[mtdparts=]<mtd-def>[;<mtd-def>...]
> >    *
> >    * <mtd-def>  := <mtd-id>:<part-def>[,<part-def>...]
> >    * <mtd-id>   := unique device tag used by linux kernel to find mtd device (mtd->name)
> > @@ -62,11 +62,11 @@
> >    *
> >    * 1 NOR Flash, with 1 single writable partition:
> >    * mtdids=nor0=edb7312-nor
> > - * mtdparts=mtdparts=edb7312-nor:-
> > + * mtdparts=[mtdparts=]edb7312-nor:-
> >    *
> >    * 1 NOR Flash with 2 partitions, 1 NAND with one
> >    * mtdids=nor0=edb7312-nor,nand0=edb7312-nand
> > - * mtdparts=mtdparts=edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)
> > + * mtdparts=[mtdparts=]edb7312-nor:256k(ARMboot)ro,-(root);edb7312-nand:-(home)
> >    *
> >    */  
> >   > @@ -1099,9 +1099,6 @@ static int generate_mtdparts(char *buf, u32 buflen)  
> >   		return 0;
> >   	}  
> >   > -	strcpy(p, "mtdparts=");  
> > -	p += 9;
> > -
> >   	list_for_each(dentry, &devices) {
> >   		dev = list_entry(dentry, struct mtd_device, link);  
> >   > @@ -1572,11 +1569,9 @@ static int parse_mtdparts(const char *const mtdparts)  
> >   	if (!p)
> >   		p = mtdparts;  
> >   > -	if (strncmp(p, "mtdparts=", 9) != 0) {  
> > -		printf("mtdparts variable doesn't start with 'mtdparts='\n");
> > -		return err;
> > -	}
> > -	p += 9;
> > +	/* Skip the useless prefix, if any */
> > +	if (strncmp(p, "mtdparts=", 9) == 0)
> > +		p += 9;  
> >   >   	while (*p != '\0') {  
> >   		err = 1;
> >   
> I always wondered about this double mtdparts thing but was never brave
> enough to touch it. ;)

If I understand correctly, this double mtdparts thing comes from lazy
people who decided to build the bootargs this way:

setenv mtdparts "mtdparts=mtddev0:-(all)"
setenv bootargs "console=/dev/tty0 [...] ${mtdparts}"

instead of this way:

setenv mtdparts "mtddev0:-(all)"
setenv bootargs "console=/dev/tty0 [...] mtdparts=${mtdparts}"

Which, personally, I find much clearer.

I'm still puzzled by the real use of mtdids, I will check this week if
I didn't broke anything in the way U-Boot and Linux share the
MTD devices and their partitions.

Thanks,
Miquèl