Re: [PATCH/RFC linux-mtd] mtd: sh_flctl: Remove sh7372 and device tree support

[Rich Felker <dalias@libc.org>]

On Tue, Nov 29, 2016 at 06:23:38PM +0100, Geert Uytterhoeven wrote:
> Hi Rich,
> 
> On Tue, Nov 29, 2016 at 6:09 PM, Rich Felker <dalias@libc.org> wrote:
> > On Fri, Nov 25, 2016 at 08:33:01AM +0100, Simon Horman wrote:
> >> Commit edf4100906044225 ("ARM: shmobile: sh7372 dtsi: Remove Legacy file")
> >> removed the sh7272 SoC from the kernel in v4.1.
> >>
> >> This patch removes support for the sh7272 SoC from the sh_flctl driver.
> >> As that SoC was the only user of device tree support also remove that
> >> from the driver.
> >>
> >> In essence it reverts commit 7c8f680e96ed ("mtd: sh_flctl: Add device tree
> >> support"). This commit may be used as a reference for re-adding device
> >> tree support to this driver if a need for it is found in future.
> >>
> >> This commit has been build-testesd against the ap325rxa_defconfig.
> >> I do not have access to the hardware to perform run-time testing
> >> on that board which appears to be the only remaining user of this driver.
> >> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
> >> ---
> >>  .../devicetree/bindings/mtd/flctl-nand.txt         | 49 ---------------
> >>  drivers/mtd/nand/sh_flctl.c                        | 70 +++-------------------
> >>  2 files changed, 8 insertions(+), 111 deletions(-)
> >>  delete mode 100644 Documentation/devicetree/bindings/mtd/flctl-nand.txt
> >
> > While I'm not the maintainer for this (and I'm not clear that the
> > linux-sh list even should have been cc'd; it seems to be shmobile arm
> > soc stuff rather than sh arch) I think this is a bad change. If the
> > driver is completely unused, it should just be removed, but if there
> 
> Its sole remaining in-kernel user is arch/sh/boards/mach-ap325rxa/setup.c.

If indeed there's a user in arch/sh, it makes even more sense not to
remove it. arch/sh/boards/* is intended to be removed with only DT
support remaining, once drivers have DT support. :-)

> > are remaining users that are still using legacy platform device
> > bindings, they should gradually be transitioned to device tree, and
> > having the device tree support still present makes it easier to do
> > that.
> 
> Enjoy converting ap325rxa to DT ;-)

Not sure if that's expected to be worse than the rest of it and if it
makes sense to convert or just remove. But I don't think changes that
put us farther away from DT-only make sense.

> > Removing the *bindings* is even worse, as these are a permanent
> > interface between hardware/firmware and software.
> 
> While it is a permanent interface, it is only a git revert away...

Indeed, but one that requires coordination between subsystem
maintainers to get it back in a working state.

Rich