[PATCH v10 12/27] mtd: spi-nor-core: Rework hwcaps selection

[Bin Meng]

Hi Pratyush,

On Wed, Jul 28, 2021 at 6:44 PM Pratyush Yadav <p.yadav at ti.com> wrote:
>
> On 28/07/21 06:13PM, Bin Meng wrote:
> > Hi Pratyush,
> >
> > On Sat, Jun 26, 2021 at 3:20 AM Pratyush Yadav <p.yadav at ti.com> wrote:
> > >
> > > The spi-mem layer provides a spi_mem_supports_op() function to check
> > > whether a specific operation is supported by the controller or not.
> > > This is much more accurate than the hwcaps selection logic based on
> > > SPI_{RX,TX}_ flags.
> > >
> > > Rework the hwcaps selection logic to use spi_mem_supports_op().
> > >
> > > To make sure the build doesn't break for boards not using CONFIG_DM_SPI,
> > > add a simple SPI_{RX,TX}_ based hwcaps selection logic in spi-mem-nodm
> > > similar to spi_mem_default_supports_op(). This change is only
> > > compile-tested.
> > >
> > > To avoid SPL size problems on the x530 board, the old hwcaps selection
> > > is still kept around. Leaving the code in-place was getting difficult to
> > > read and understand, so the code is restructured to have it all in one
> > > isolated function. As a result of this, the parameter hwcaps to
> > > spi_nor_setup() is no longer needed. Remove it.
> > >
> > > Based on the Linux commit c76f5089796a (mtd: spi-nor: Rework hwcaps
> > > selection for the spi-mem case, 2019-08-06)
> > >
> > > Signed-off-by: Pratyush Yadav <p.yadav at ti.com>
> > > ---
> > >  drivers/mtd/spi/Kconfig        |   9 ++
> > >  drivers/mtd/spi/spi-nor-core.c | 244 ++++++++++++++++++++++++++-------
> > >  drivers/spi/spi-mem-nodm.c     |  62 +++++++++
> > >  include/linux/mtd/spi-nor.h    |  17 ++-
> > >  4 files changed, 280 insertions(+), 52 deletions(-)
> > >
> > > diff --git a/drivers/mtd/spi/Kconfig b/drivers/mtd/spi/Kconfig
> > > index f8db8e5213..a701167dcc 100644
> > > --- a/drivers/mtd/spi/Kconfig
> > > +++ b/drivers/mtd/spi/Kconfig
> > > @@ -88,6 +88,15 @@ config SPI_FLASH_SFDP_SUPPORT
> > >          SPI NOR flashes using Serial Flash Discoverable Parameters (SFDP)
> > >          tables as per JESD216 standard.
> > >
> > > +config SPI_FLASH_SMART_HWCAPS
> > > +       bool "Smart hardware capability detection based on SPI MEM supports_op() hook"
> > > +       default y
> >
> > This commit unfortunately breaks ICH SPI driver working with SPI
> > flashes on Intel boards.
> >
> > Switching off this option makes it work again.
> >
> > I think this is due to that ICH SPI driver has set the flags
> > SPI_RX_SLOW | SPI_TX_BYTE but these 2 flags are not handled in the new
> > codes.
> > Any quick ideas on how to fix this?
>
> So can the controller can only support 1S-1S-1S mode? Or can the
> controller support more modes but the board does not have the other
> lines connected?
>
> For the former case, you should populate the supports_op() hook and
> reject ops that are not 1S-1S-1S. For the latter case, you should set
> spi-{rx,tx}-bus-width = <1> in device tree.

Thank you. I just sent a RFC patch that fixed this issue.

>
> Make sure you call spi_mem_default_supports_op() from your supports_op()
> hook otherwise the slave->mode bits are not taken into account.
>
> >
> > > +       help
> > > +        Enable support for smart hardware capability detection based on SPI
> > > +        MEM supports_op() hook that lets controllers express whether they
> > > +        can support a type of operation in a much more refined way compared
> > > +        to using flags like SPI_RX_DUAL, SPI_TX_QUAD, etc.
> > > +
> >
> > [snip]
> >

Regards,
Bin