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

Mika Westerberg
2022-06-16T13:00:11Z

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@cisco.com>
> > 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@linux.intel.com
> > 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@linux.intel.com/ 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.