RE: [PATCH v3 2/2] mtd: spi-nor: Avoid setting SRWD bit in SR if WP# signal not connected

[Mahapatra, Amit Kumar]

Hello Tudor,

> -----Original Message-----
> From: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx>
> Sent: Friday, June 30, 2023 2:18 PM
> To: Michael Walle <michael@xxxxxxxx>; Mahapatra, Amit Kumar
> <amit.kumar-mahapatra@xxxxxxx>
> Cc: pratyush@xxxxxxxxxx; miquel.raynal@xxxxxxxxxxx; richard@xxxxxx;
> vigneshr@xxxxxx; robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx;
> conor+dt@xxxxxxxxxx; git (AMD-Xilinx) <git@xxxxxxx>; linux-
> mtd@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; amitrkcian2002@xxxxxxxxx
> Subject: Re: [PATCH v3 2/2] mtd: spi-nor: Avoid setting SRWD bit in SR if WP#
> signal not connected
> 
> 
> 
> On 6/27/23 07:14, Michael Walle wrote:
> > Am 2023-06-25 12:02, schrieb Amit Kumar Mahapatra:
> >> Setting the status register write disable (SRWD) bit in the status
> >> register (SR) with WP# signal of the flash left floating or wrongly
> >> tied to GND (that includes internal pull-downs), will configure the
> >> SR permanently as read-only. If WP# signal is left floating or
> >> wrongly tied to GND, avoid setting SRWD bit while writing the SR during
> flash protection.
> >>
> >> Signed-off-by: Amit Kumar Mahapatra <amit.kumar-
> mahapatra@xxxxxxx>
> >> ---
> >>  drivers/mtd/spi-nor/core.c | 3 +++
> >>  drivers/mtd/spi-nor/core.h | 1 +
> >>  drivers/mtd/spi-nor/swp.c  | 9 +++++++--
> >>  3 files changed, 11 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> >> index 0bb0ad14a2fc..520f5ab86d2b 100644
> >> --- a/drivers/mtd/spi-nor/core.c
> >> +++ b/drivers/mtd/spi-nor/core.c
> >> @@ -2864,6 +2864,9 @@ static void spi_nor_init_flags(struct spi_nor
> >> *nor)
> >>      if (flags & NO_CHIP_ERASE)
> >>          nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
> >>
> >> +    if (of_property_read_bool(np, "no-wp"))
> >> +        nor->flags |= SNOR_F_NO_WP;
> >> +
> >
> > Please put it below the of_property_read_bool() which is already
> > there, just to keep things sorted.
> >
> >>      if (flags & SPI_NOR_RWW && nor->info->n_banks > 1 &&
> >>          !nor->controller_ops)
> >>          nor->flags |= SNOR_F_RWW;
> >> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> >> index 4fb5ff09c63a..55b5e7abce6e 100644
> >> --- a/drivers/mtd/spi-nor/core.h
> >> +++ b/drivers/mtd/spi-nor/core.h
> >> @@ -132,6 +132,7 @@ enum spi_nor_option_flags {
> >>      SNOR_F_SWP_IS_VOLATILE    = BIT(13),
> >>      SNOR_F_RWW        = BIT(14),
> >>      SNOR_F_ECC        = BIT(15),
> >> +    SNOR_F_NO_WP        = BIT(16),
> >
> > See the comment right above this enum :/
> >
> >>  };
> >>
> >>  struct spi_nor_read_command {
> >> diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
> >> index 0ba716e84377..cfaba41d74d6 100644
> >> --- a/drivers/mtd/spi-nor/swp.c
> >> +++ b/drivers/mtd/spi-nor/swp.c
> >> @@ -214,8 +214,13 @@ static int spi_nor_sr_lock(struct spi_nor *nor,
> >> loff_t ofs, uint64_t len)
> >>
> >>      status_new = (status_old & ~mask & ~tb_mask) | val;
> >>
> >> -    /* Disallow further writes if WP pin is asserted */
> >> -    status_new |= SR_SRWD;
> >> +    /*
> >> +     * Disallow further writes if WP# pin is neither left floating
> >> +nor
> >> +     * wrongly tied to GND(that includes internal pull-downs).
> >
> > nit: space missing
> >
> > Otherwise looks good.
> >
> 
> Thanks, Michael.
> 
> Amit, would be good if you can address Michael's comments and resubmit. If
> not, I'll amend the patch by myself when applying.

I will address Michael's comments and send the next series.

Regards,
Amit
> 
> Cheers,
> ta