[PATCH] mtd: m25p80: Make the name of mtd_info fixed

[PATCH] mtd: m25p80: Make the name of mtd_info fixed

[Hou Zhiqiang]

To give spi flash layout using "mtdparts=..." in cmdline, we must
give mtd_info a fixed name,because the cmdlinepart's parser will
match the name given in cmdline with the mtd_info.

Now, if use OF node, mtd_info's name will be spi->dev->name. It
consists of spi_master->bus_num, and the spi_master->bus_num maybe
dynamically fetched.
So, give the mtd_info a new fiexd name "name.cs", "name" is name of
spi_device_id and "cs" is chip-select in spi_dev.

Signed-off-by: Hou Zhiqiang <b48286@freescale.com>
---
 drivers/mtd/devices/m25p80.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index eb558e8..d1ed480 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -1012,7 +1012,8 @@ static int m25p_probe(struct spi_device *spi)
 	if (data && data->name)
 		flash->mtd.name = data->name;
 	else
-		flash->mtd.name = dev_name(&spi->dev);
+		flash->mtd.name = kasprintf(GFP_KERNEL, "%s.%d",
+				id->name, spi->chip_select);
 
 	flash->mtd.type = MTD_NORFLASH;
 	flash->mtd.writesize = 1;
-- 
1.8.4.1

Re: [PATCH] mtd: m25p80: Make the name of mtd_info fixed

[Brian Norris]

Hi Hou,

On Mon, Jan 06, 2014 at 02:34:29PM +0800, Hou Zhiqiang wrote:
> To give spi flash layout using "mtdparts=..." in cmdline, we must
> give mtd_info a fixed name,because the cmdlinepart's parser will
> match the name given in cmdline with the mtd_info.
> 
> Now, if use OF node, mtd_info's name will be spi->dev->name. It
> consists of spi_master->bus_num, and the spi_master->bus_num maybe
> dynamically fetched.
> So, give the mtd_info a new fiexd name "name.cs", "name" is name of
> spi_device_id and "cs" is chip-select in spi_dev.
> 
> Signed-off-by: Hou Zhiqiang <b48286@freescale.com>
> ---
>  drivers/mtd/devices/m25p80.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index eb558e8..d1ed480 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -1012,7 +1012,8 @@ static int m25p_probe(struct spi_device *spi)
>  	if (data && data->name)
>  		flash->mtd.name = data->name;
>  	else
> -		flash->mtd.name = dev_name(&spi->dev);
> +		flash->mtd.name = kasprintf(GFP_KERNEL, "%s.%d",
> +				id->name, spi->chip_select);

Changing the mtd.name may have far-reaching consequences for users who
already have mtdparts= command lines. But your concern is probably valid
for dynamically-determined bus numbers. Perhaps you can edit this patch
to only change the name when the busnum is dynamically-allocated?

This also needs a NULL check (for OOM), and you leak memory on device
removal.

>  
>  	flash->mtd.type = MTD_NORFLASH;
>  	flash->mtd.writesize = 1;

Brian

RE: [PATCH] mtd: m25p80: Make the name of mtd_info fixed

[B48286]

Hi Brian,
Thanks for your comments!

> -----Original Message-----
> From: Brian Norris [mailto:computersforpeace@gmail.com]
> Sent: Thursday, January 23, 2014 10:12 AM
> To: Hou Zhiqiang-B48286
> Cc: linux-mtd@lists.infradead.org; linuxppc-dev@ozlabs.org; Wood Scott-
> B07421; Hu Mingkai-B21284; Ezequiel Garcia
> Subject: Re: [PATCH] mtd: m25p80: Make the name of mtd_info fixed
>=20
> Hi Hou,
>=20
> On Mon, Jan 06, 2014 at 02:34:29PM +0800, Hou Zhiqiang wrote:
> > To give spi flash layout using "mtdparts=3D..." in cmdline, we must giv=
e
> > mtd_info a fixed name,because the cmdlinepart's parser will match the
> > name given in cmdline with the mtd_info.
> >
> > Now, if use OF node, mtd_info's name will be spi->dev->name. It
> > consists of spi_master->bus_num, and the spi_master->bus_num maybe
> > dynamically fetched.
> > So, give the mtd_info a new fiexd name "name.cs", "name" is name of
> > spi_device_id and "cs" is chip-select in spi_dev.
> >
> > Signed-off-by: Hou Zhiqiang <b48286@freescale.com>
> > ---
> >  drivers/mtd/devices/m25p80.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mtd/devices/m25p80.c
> > b/drivers/mtd/devices/m25p80.c index eb558e8..d1ed480 100644
> > --- a/drivers/mtd/devices/m25p80.c
> > +++ b/drivers/mtd/devices/m25p80.c
> > @@ -1012,7 +1012,8 @@ static int m25p_probe(struct spi_device *spi)
> >  	if (data && data->name)
> >  		flash->mtd.name =3D data->name;
> >  	else
> > -		flash->mtd.name =3D dev_name(&spi->dev);
> > +		flash->mtd.name =3D kasprintf(GFP_KERNEL, "%s.%d",
> > +				id->name, spi->chip_select);
>=20
> Changing the mtd.name may have far-reaching consequences for users who
> already have mtdparts=3D command lines. But your concern is probably vali=
d
> for dynamically-determined bus numbers. Perhaps you can edit this patch
> to only change the name when the busnum is dynamically-allocated?
>
It's a good idea, but in the case of mtd_info's name dynamically-allocated
using "mtdparts=3D..." in command lines is illegal obviously. Would you tel=
l
me what side-effect will be brought by the change of mtd_info's name.
Thanks=20
=20
> This also needs a NULL check (for OOM), and you leak memory on device
> removal.
>=20
Yes, it's necessary to check the return value of function kasprintf.

> >
> >  	flash->mtd.type =3D MTD_NORFLASH;
> >  	flash->mtd.writesize =3D 1;
>=20
> Brian
>=20
Thanks,
Hou Zhiqiang

Re: [PATCH] mtd: m25p80: Make the name of mtd_info fixed

[Brian Norris]

Hi Hou,

On Thu, Jan 23, 2014 at 03:29:41AM +0000, B48286@freescale.com wrote:
> > -----Original Message-----
> > From: Brian Norris [mailto:computersforpeace@gmail.com]
> > Sent: Thursday, January 23, 2014 10:12 AM
> > To: Hou Zhiqiang-B48286
> > Cc: linux-mtd@lists.infradead.org; linuxppc-dev@ozlabs.org; Wood Scott-
> > B07421; Hu Mingkai-B21284; Ezequiel Garcia
> > Subject: Re: [PATCH] mtd: m25p80: Make the name of mtd_info fixed
> > 
> > On Mon, Jan 06, 2014 at 02:34:29PM +0800, Hou Zhiqiang wrote:
> > > --- a/drivers/mtd/devices/m25p80.c
> > > +++ b/drivers/mtd/devices/m25p80.c
> > > @@ -1012,7 +1012,8 @@ static int m25p_probe(struct spi_device *spi)
> > >  	if (data && data->name)
> > >  		flash->mtd.name = data->name;
> > >  	else
> > > -		flash->mtd.name = dev_name(&spi->dev);
> > > +		flash->mtd.name = kasprintf(GFP_KERNEL, "%s.%d",
> > > +				id->name, spi->chip_select);
> > 
> > Changing the mtd.name may have far-reaching consequences for users who
> > already have mtdparts= command lines. But your concern is probably valid
> > for dynamically-determined bus numbers. Perhaps you can edit this patch
> > to only change the name when the busnum is dynamically-allocated?
> >
> It's a good idea, but in the case of mtd_info's name dynamically-allocated
> using "mtdparts=..." in command lines is illegal obviously.

I agree that users should never have relied on the dynamically-allocated
name. But changing the name for non-dynamic schemes (e.g., where the SPI
busnum is a fixed value) is not pleasant for users.

> Would you tell
> me what side-effect will be brought by the change of mtd_info's name.

I can only think of the mtdparts= command line. Otherwise, I don't think
the name is very important.

Brian