Re: [PATCH v2] mtd: spi-nor: handle unsupported FSR opcodes properly

[Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>]

On Thu, Jun 16, 2022 at 12:54:42PM +0000, Oleksandr Ocheretnyi -X (oocheret - GLOBALLOGIC INC at Cisco) wrote:
>    Hi,
> 
>      > Originally commit 094d3b9 ("mtd: spi-nor: Add USE_FSR flag for
>      n25q*
>      > entries") and following one 8f93826 ("mtd: spi-nor: micron-st:
>      convert
>      > USE_FSR to a manufacturer flag") enabled SPINOR_OP_RDFSR opcode
>      handling
>      > ability, however some controller drivers still cannot handle it
>      properly
>      > in the micron_st_nor_ready() call what breaks some mtd callbacks
>      with
>      > next error logs:
>      >
>      > mtdblock: erase of region [address1, size1] on "BIOS" failed
>      > mtdblock: erase of region [address2, size2] on "BIOS" failed
>      >
>      > The Intel SPI controller does not support low level operations,
>      like
>      > reading the flag status register (FSR). It only exposes a set of
>      high
>      > level operations for software to use. For this reason check the
>      return
>      > value of micron_st_nor_read_fsr() and if the operation was not
>      > supported, use the status register value only. This allows the
>      chip to
>      > work even when attached to Intel SPI controller (there are such
>      systems
>      > out there).
>      >
>      > Signed-off-by: Oleksandr Ocheretnyi <oocheret@xxxxxxxxx>
>      > Link: [1]https://lore.kernel.org/lkml/YmZUCIE%2FND82BlNh@lahna/
>      > ---
>      >  PATCH v2 updates PATCH v1 taking into account changes from
>      >
>      [2]https://lore.kernel.org/linux-mtd/20220506105158.43613-1-mika.wes
>      terberg@xxxxxxxxxxxxxxx
>      >  to check -EOPNOTSUPP value from micron_st_nor_read_fsr() as well.
>      >
>      >  drivers/mtd/spi-nor/micron-st.c | 12 ++++++++++--
>      >  drivers/spi/spi-intel.c         |  3 ++-
>      >  2 files changed, 12 insertions(+), 3 deletions(-)
>      >
>      > diff --git a/drivers/mtd/spi-nor/micron-st.c
>      b/drivers/mtd/spi-nor/micron-st.c
>      > index a96f74e0f568..fd52e8feea44 100644
>      > --- a/drivers/mtd/spi-nor/micron-st.c
>      > +++ b/drivers/mtd/spi-nor/micron-st.c
>      > @@ -399,8 +399,16 @@ static int micron_st_nor_ready(struct spi_nor
>      *nor)
>      >                return sr_ready;
>      >
>      >        ret = micron_st_nor_read_fsr(nor, nor->bouncebuf);
>      > -     if (ret)
>      > -             return ret;
>      > +     if (ret < 0) {
>      > +             /*
>      > +              * Some controllers, such as Intel SPI, do not
>      support low
>      > +              * level operations such as reading the flag status
>      > +              * register. They only expose small amount of high
>      level
>      > +              * operations to the software. If this is the case
>      we use
>      > +              * only the status register value.
>      > +              */
>      > +             return (ret == -ENOTSUPP || ret == -EOPNOTSUPP) ?
>      sr_ready : ret;
>      The -EOPNOTSUPP here is not needed as you change the Intel SPI
>      driver in
> 
>    the below.
> 
>    ​However I remember you caught situation where micron_st_nor_read_fsr()
>    returns -EOPNOTSUPP
>    (intel_spi_exec_mem_op callback returns -EOPNOTSUPP), according to your
>    patch
>    [3]https://lore.kernel.org/linux-mtd/20220506105158.43613-1-mika.wester
>    berg@xxxxxxxxxxxxxxx/ I've noted in description body. So I think I have
>    to cover both errorcodes, haven't I?

I was thinking that you change the both functions in Intel SPI to return
-ENOTSUPP, not just one.

>    Or your patch as well as my one are going submitted independently and
>    can be merged sequentially?

No, my patch can be ignored.