Re: [PATCH V3] Add support for flag status register on Micron chips.

Huang Shijie
2014-04-26T03:10:52Z

On Sat, Apr 26, 2014 at 12:12:24AM +0200, Marek Vasut wrote:
> > > > the drivers may fills this hook itself, so the code should like this:
> > > > --------------------------------------------------
> > > >
> > > > if ((info->flags & USE_FSR) &&
> > > >
> > > > nor->wait_till_ready == spi_nor_wait_till_fsr_ready)
> > > >
> > > > nor->wait_till_ready = spi_nor_wait_till_fsr_ready;
> > > >
> > > > --------------------------------------------------
> > >
> > > I sense a misdesign of the SPI NOR subsystem here. The subsystem and the
> > > driver compete for a function pointer here ? I guess one should have
> > > precedence in some way then ... and also, they should be two different
> > > pointers, where the subsystem decides which to use.
> >
> > the subsystem do not decides which one to use, the driver decides which one
> > to use.
> >
> > If driver has its own @wait_till_ready , it means the driver knows the
> > feature, and has implemented it in its own @wait_till_ready.
> >
> > If the driver does not fill any wait_till_ready, it means the driver will
> > use the default @wait_till_ready. We can treat the
> > spi_nor_wait_till_fsr_ready as a default hook too.
>
> I see the driver overwriting a hook previously set by the subsystem. This
not sure ;)

The driver set the hooks before the subsystem set these hooks.

If the driver has already set the @wait_till_ready hook before it calls
the spi_nor_scan, the subsystem will not set the hook anymore.

Please see the spi_nor_check().

thanks
Huang Shijie