RE: [PATCH 06/10] drm/i915/spi: spi register with mtd

Usyskin, Alexander
2023-11-14T08:47:59Z

>
> > > > > > + spi->mtd.writesize = SZ_1; /* 1 byte granularity */
> > > > >
> > > > > You say writesize should be aligned with 4 in your next patch?
> > > >
> > > > We support unaligned write by reading aligned 4bytes,
> > > > replacing changed bytes there and writing whole 4bytes back.
> > > > Is there any problem with this approach?
> > >
> > > Is there a reason to do that manually rather than letting the core
> > > handle the complexity?
> > >
> > I was not aware that core can do this. The core implements above logic
> > if I put SZ_4 here and caller try to write, say, one byte?
> > And sync multiple writers?
> > If so, I can remove manual work, I think, and make the patches smaller.
>
> I haven't checked in detail but I would expect this yes. Please have a
> round of tests and if it works, please simplify this part.
>
> Thanks,
> Miquèl

When I put SZ_4 here the "mtd_debug info /dev/mtd0" prints "mtd.writesize = 4",
but "mtd_debug write /dev/mtd0 128 1 c" passes one byte to
i915_spi_write (mtd._write callback).
I suppose that mtd subsystem do not support this.
Or I did something wrong?

--
Thanks,
Sasha