Re: [RFC PATCH 1/2] mtd: spi-nor: atmel: remove global SNOR_F_HAS_LOCK

[Michael Walle]

Am 2020-10-01 16:06, schrieb Tudor.Ambarus@xxxxxxxxxxxxx:
> On 10/1/20 3:28 PM, Michael Walle wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know 
> > the content is safe
> >
> > This is considered bad for the following reasons:
> >  (1) We only support the block protection with BPn bits for write
> >      protection. Not all Atmel parts support this.
> >  (2) Newly added flash chip will automatically inherit the "has
> >      locking" support and thus needs to explicitly tested. Better
> >      be opt-in instead of opt-out.
> >  (3) There are already supported flashes which don't support the 
> > locking
> >          scheme. So I assume this wasn't properly tested before adding 
> > that
> >          chip; which enforces my previous argument that locking 
> > support should
> >          be an opt-in.
> >
> > Remove the global flag and add individual flags to all flashes
> > which supports BP locking. In particular the following flashes
> > don't support the BP scheme:
> >  - AT26F004
> >  - AT25SL321
> >  - AT45DB081D
> >
> > Signed-off-by: Michael Walle <michael@xxxxxxxx>
> > ---
> >  drivers/mtd/spi-nor/atmel.c | 28 +++++++++-------------------
> >  1 file changed, 9 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
> > index 3f5f21a473a6..49d392c6c8bc 100644
> > --- a/drivers/mtd/spi-nor/atmel.c
> > +++ b/drivers/mtd/spi-nor/atmel.c
> > @@ -10,37 +10,27 @@
> >
> >  static const struct flash_info atmel_parts[] = {
> >         /* Atmel -- some are (confusingly) marketed as "DataFlash" */
> > -       { "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K) },
> > -       { "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K) },
> > +       { "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K | 
> > SPI_NOR_HAS_LOCK) },
> > +       { "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K | 
> > SPI_NOR_HAS_LOCK) },
>
> after a quick look in the datasheets of these flashes, I suspect that
> what we have now in the SPI NOR core for SR locking does not work for
> them. They probably supported just "unlock all", clearing all the
> BP bits. Anyway, different problem.
> > -       { "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K) },
> > -       { "at25df321",  INFO(0x1f4700, 0, 64 * 1024,  64, SECT_4K) },
> > -       { "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64, SECT_4K) },
> > -       { "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K) },
> > +       { "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K | 
> > SPI_NOR_HAS_LOCK) },
>
> this one does not support BP locking:
> https://www.adestotech.com/wp-content/uploads/doc3668.pdf
>
> > +       { "at25df321",  INFO(0x1f4700, 0, 64 * 1024,  64, SECT_4K | 
> > SPI_NOR_HAS_LOCK) },
>
> neither this one:
> https://datasheet.octopart.com/AT25DF321-S3U-Atmel-datasheet-8700896.pdf
>
> > +       { "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64, SECT_4K | 
> > SPI_NOR_HAS_LOCK) },
>
> nor this one: https://www.adestotech.com/wp-content/uploads/doc3686.pdf
>
> > +       { "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K | 
> > SPI_NOR_HAS_LOCK) },
>
> nor this one: https://www.adestotech.com/wp-content/uploads/doc3680.pdf
>
> I stop here.

These are all the ones which use the global unlock. I cannot just skip
the HAS_LOCK bit here, because otherwise this patch wouldn't be 
backwards
compatibe. Yes I missed that in the commit log, my bad.

-michael