[U-Boot] [PATCH 03/16] spi: Add non DM version of SPI_MEM

[Tom Rini]

On Thu, Dec 13, 2018 at 04:40:30AM +0530, Jagan Teki wrote:
> On Thu, Dec 13, 2018 at 2:55 AM Boris Brezillon
> <boris.brezillon at bootlin.com> wrote:
> >
> > On Wed, 12 Dec 2018 22:07:44 +0100
> > Jagan Teki <jagan at amarulasolutions.com> wrote:
> >
> > > On Wed 12 Dec, 2018, 10:02 PM Boris Brezillon <boris.brezillon at bootlin.com
> > > wrote:
> > >
> > > > On Thu, 13 Dec 2018 02:15:16 +0530
> > > > Jagan Teki <jagan at amarulasolutions.com> wrote:
> > > >
> > > > > On Thu, Dec 13, 2018 at 2:10 AM Boris Brezillon
> > > > > <boris.brezillon at bootlin.com> wrote:
> > > > > >
> > > > > > Hi Jagan,
> > > > > >
> > > > > > On Thu, 13 Dec 2018 01:55:08 +0530
> > > > > > Jagan Teki <jagan at amarulasolutions.com> wrote:
> > > > > >
> > > > > > > On Wed, Dec 12, 2018 at 11:08 PM Vignesh R <vigneshr at ti.com>
> > > > wrote:
> > > > > > > >
> > > > > > > > Add non DM version of SPI_MEM to support easy migration to new SPI
> > > > NOR
> > > > > > > > framework. This can be removed once DM_SPI conversion is
> > > > complete.
> > > > > > >
> > > > > > > Our intention to use new driver to follow dm, why we need to support
> > > > > > > non-dm? any usecases?
> > > > > >
> > > > > > Looks like we're having the same discussion over and over. Vignesh is
> > > > > > dropping spi_flash.c which AFAICT was not depending on DM_SPI, so, if
> > > > > > we want to keep everyone happy while getting rid of some legacy code,
> > > > > > that's the only solution. DM conversion is a nice goal, but it's kind
> > > > > > of orthogonal to what Vignesh is working on. If DM_SPI conversion
> > > > > > happens before the spi-nor stuff is merged  (which I doubt) then this
> > > > > > patch can simply be dropped.
> > > > >
> > > > > spi_flash.c is a core code not a specific driver it belongs. spi-mem
> > > > > is new feature driver how come new driver will support legacy non-dm
> > > > > do we have legacy use for that(ie what I'm asking about usecase)
> > > >
> > > > I recommend that you read the spi-mem code carefully. spi-mem is not
> > > > driver specific, it's a thin layer on top of spi and driver *can* (but
> > > > are not forced to) provide optimized methods to execute spi-mem
> > > > operations. When that's not the case, the implementation falls back to
> > > > regular spi transfers. AFAIK, both DM and non-DM drivers support
> > > > regular spi transfers, right? So why should we depend on DM_SPI? And
> > > > more importantly, if we do that, that means we can't get rid of
> > > > spi_flash.c since some users might still have non-DM SPI drivers, which
> > > > in turn means we keep more legacy code for no good reasons.
> > > >
> > >
> > > I understand spi-mem is core file, but new code too.
> >
> > Sorry, I don't get it.
> >
> > >
> > >
> > > > You want non-DM SPI controller drivers to go away, then remove them,
> > > > instead of blocking other changes using this excuse.
> > > >
> > >
> > > Please understand uboot development flow, legacy driver can be removed if
> > > possible once migration expire and NEW drivers or code must be dm driven.
> >
> > Sorry, but I think you're the one misunderstanding what we are trying
> > to do here. Vignesh changes have simply no impact on the DM SPI
> > conversion you're aiming at. All Vignesh does is provide a dummy
> > wrapper for non-DM drivers, which would probably have been implemented
> > by Miquel if you had not been so insistent on your precious DM_SPI
> > conversion. That was not really a problem for spi-nand, as we were
> 
> I'm sure, I'm in right direction.
> 
> This is what I asked in the first mail,
> 
> "Our intention to use new driver to follow dm, why we need to support
> non-dm? any usecases?"
> 
> and I have the answer on this thread about the use case.
> 
> I do really understand your intention about the real question.
> - Any code or generic code will add in U-Boot should be driver-model
> driven, are you agree this point?
>   Yes- thanks.
>   No - we need to have separate discussion.
> 
> Any code that related to spi, or spi-flash should be driver-model
> driven, ie what my AIM as a Maintainer (ie only reason for my spi-nor
> changes resist for long time to fit).

And since we have both been "stuck" for so very long and a clear
commitment from a few people to follow through on the "and DM it after"
part, I'm OK with bending the rules.

-- 
Tom
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