Re: [PATCH v3 2/3] mtd: spi-nor: add 4bit block protection support

[Jungseung Lee <js07.lee@xxxxxxxxx>]

Hi, Tudor,

On Tue, Jan 14, 2020 at 7:49 PM <Tudor.Ambarus@xxxxxxxxxxxxx> wrote:
>
> Hi, Jungseung,
>
> Thanks for working on this.
>
> On Monday, January 13, 2020 7:59:06 AM EET Jungseung Lee wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> > content is safe
> >
> > Currently, we are supporting block protection only for
> > flash chips with 3 block protection bits in the SR register.
> > This patch enables block protection support for some flash with
> > 4 block protection bits(bp0-3).
>
> Some? Isn't this generic for all the flashes that support BP0-3?
>

This one would be a generic solution to support BP0-3 on Status Register.
>From my study, this covers all the flashes listed on spi-nor.c that
have BP0-3 bit on SR.
It looks like I have to change this description.

Note that it is NOT for some flashes that have BP0-3 in another register.
As you know, just like SPI_NOR_HAS_TB did.

> >
> > Signed-off-by: Jungseung Lee <js07.lee@xxxxxxxxxxx>
> > ---
> > v3 :
> >   Fix wrong ofs calculation on v2 patch
> > v2 :
> >   Add sample table portion about 4bit block protection on the comment
> >   Trivial coding style change
> >
> >  drivers/mtd/spi-nor/spi-nor.c | 127 +++++++++++++++++++++++++++++-----
> >  include/linux/mtd/spi-nor.h   |   8 +++
> >  2 files changed, 119 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> > index e3da6a8654a8..7e8af6c4fdfa 100644
> > --- a/drivers/mtd/spi-nor/spi-nor.c
> > +++ b/drivers/mtd/spi-nor/spi-nor.c
> > @@ -238,6 +238,14 @@ struct flash_info {
> >                                          * status register. Must be used
> > with * SPI_NOR_HAS_TB.
> >                                          */
> > +#define SPI_NOR_HAS_BP3                BIT(17) /*
> > +                                        * Flash SR has 4 bit fields (BP0-3)
> > +                                        * for block protection.
> > +                                        */
> > +#define SPI_NOR_BP3_SR_BIT6    BIT(18) /*
> > +                                        * BP3 is bit 6 of status register.
> > +                                        * Must be used with
>
> Are we safe to replace SPI_NOR_TB_SR_BIT6 and SPI_NOR_BP3_SR_BIT6 with a
> SPI_NOR_SR_TB_BIT6_BP3_BIT5? Or maybe with a SPI_NOR_SR_BP3_BIT6_TB_BIT5, how
> is more convenient?
>

Let's think about some flash in which BP0-3 exists in the status
register but TB exists in another register.
for example, mx25u12835f.
I haven't tested yet, but according to the datasheet, I think this
patch can support 4bit block protection for the flash.

In order to embrace the case, how about letting them as It is.
Is there any suggestion?

> Cheers,
> ta
>

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