Hi Sergei,

> "Sergei Shtylyov" <sergei.shtylyov@cogentembedded.com> 
> 2019/05/10 ¤W¤È 03:24
> 
> To
> 
> masonccyang@mxic.com.tw, "Lee Jones" <lee.jones@linaro.org>, "Marek 
> Vasut" <marek.vasut@gmail.com>, 
> 
> cc
> 
> bbrezillon@kernel.org, broonie@kernel.org, 
> devicetree@vger.kernel.org, "Geert Uytterhoeven" <geert
> +renesas@glider.be>, "Simon Horman" <horms@verge.net.au>, 
> juliensu@mxic.com.tw, linux-kernel@vger.kernel.org, linux-renesas-
> soc@vger.kernel.org, linux-spi@vger.kernel.org, 
> mark.rutland@arm.com, "Rob Herring" <robh@kernel.org>, 
zhengxunli@mxic.com.tw
> 
> Subject
> 
> Re: [PATCH v12 3/3] dt-bindings: mfd: Document Renesas R-Car Gen3 
> RPC-IF MFD bindings
> 
> Hello!
> 
> On 05/09/2019 05:06 AM, masonccyang@mxic.com.tw wrote:
> 
> [...]
> >> > >> > On 4/24/19 11:23 PM, Rob Herring wrote:
> >> > >> > > On Wed, Apr 24, 2019 at 03:55:36PM +0800, Mason Yang wrote:
> >> > >> > >> Document the bindings used by the Renesas R-Car Gen3 RPC-IF 
MFD.
> >> > >> > >>
> >> > >> > >> Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>
> >> > >> > >> ---
> >> > >> > >>  .../devicetree/bindings/mfd/mfd-renesas-rpc.txt    | 40 
++++++
> >> > >> ++++++++++++++++
> >> > >> > >>  1 file changed, 40 insertions(+)
> >> > >> > >>  create mode 100644 
Documentation/devicetree/bindings/mfd/mfd-
> >> > >> renesas-rpc.txt
> >> > >> > >>
> >> > >> > >> diff --git 
a/Documentation/devicetree/bindings/mfd/mfd-renesas-
> >> > >> rpc.txt 
b/Documentation/devicetree/bindings/mfd/mfd-renesas-rpc.txt
> >> > >> > >> new file mode 100644
> >> > >> > >> index 0000000..668b822
> >> > >> > >> --- /dev/null
> >> > >> > >> +++ 
b/Documentation/devicetree/bindings/mfd/mfd-renesas-rpc.txt
> >> > >> > >> @@ -0,0 +1,40 @@
> >> > >> > >> +Renesas R-Car Gen3 RPC-IF MFD Device Tree Bindings
> >> > >> > >> +--------------------------------------------------
> >> > >> > >
> >> > >> > > Looks like a SPI flash controller from the example. What
> makes it an
> >> > >> > > MFD?
> >> > >> >
> >> > >> > It supports both SPI NOR and HyperFlash (CFI-compliant flash 
with
> >> > >> > different bus interface).
> >> > >>
> >> > >> Looks like you're registering one OR the other.
> >> > >>
> >> > >> Why don't you just do this from DT?
> >> > >>
> >> > >> No reason for this to be an MFD IMHO.
> >> > >
> >> > >
> >> > > okay, I will patch it back to SPI mode only.
> >> >
> >> > I don't think that's what Lee meant . The controller supports 
_both_
> >> > modes , hence it would have the same compatible string. You just 
need to
> >> > extract the mode of operation from the DT.
> >>
> >> HiSilicon attempted to upstream something similar, only their
> >> controller provided NAND and NOR functionality.  They used different
> >> compatible strings to differentiate between the varying
> >> technologies.
> >>
> >> They too tried to use MFD as a means to select between them (which 
was
> >> also NACKed).  Not sure what they ended up doing, but the original
> >> submission and (half of) the conversation can be found at [0].  Some
> >> more of the thread continues at [1].
> >>
> >> Hope that helps.
> >>
> >> [0] 
https://groups.google.com/forum/#!topic/fa.linux.kernel/F6i9o8sfOIw
> >> [1] https://marc.info/?l=devicetree&m=147669165104431&w=2
> > 
> > 
> > Hi Marek,
> > 
> > By Jones's comments:
> > 
--------------------------------------------------------------------------
> >> From: Shunquan Lin <linshunquan1@hisilicon.com>
> >>
> >> This patch adds driver support for HiSilicon Flash Memory
> >> Controller(FMC). HiSilicon FMC is a multi-functions device which
> >> supports SPI Nor flash controller, SPI nand Flash controller and
> >> parallel nand flash controller.
> > 
> > MFDs are for devices which span multiple subsystems.
> 
>    And we do! One of the subdrivers will live under drivers/spi/, the 
other
> under drivers/mtd/...
> 

From my point of view, I think Jones mean to MFD's subsystems are working 
simultaneously
at the run-time, one period of time is working for sub-device-1 and later 
period of time
is working for sub-device-2 and so on.

But for RPC-IF, SPI or HF mode is decided at boot time by pins configure 
and later in kernel
by dtb, RPC-IF can't switch SPI and HF mode at the run time.


> > 
> > Please submit this to MTD.
> > 
> > _https://marc.info/?l=devicetree&m=147376842210229&w=2_
> > 
> 
-------------------------------------------------------------------------------------------------
> > 
> > 
> > I will patch RPC-IF back to SPI mode according to previous patches:
> 
>    I still don't see why you want to do this...
> 
> > 
-----------------------------------------------------------------------
> > On 2/12/19 3:22 PM, Mark Brown wrote:
> >> The patch
> >>
> >>    spi: Add Renesas R-Car Gen3 RPC-IF SPI controller driver
> >>
> >> has been applied to the spi tree at
> >>
> >>    https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git
> >>
> >> All being well this means that it will be integrated into the 
linux-next
> >> tree (usually sometime in the next 24 hours) and sent to Linus during
> >> the next merge window (or sooner if it is a bug fix), however if
> >> problems are discovered then the patch may be dropped or reverted. 
> >>
> >> You may get further e-mails resulting from automated or manual 
testing
> >> and review of the tree, please engage with people reporting problems 
and
> >> send followup patches addressing any issues that are reported if 
needed.
> >>
> >> If any updates are required or you are submitting further changes 
they
> >> should be sent as incremental updates against current git, existing
> >> patches will not be replaced.
> >>
> >> Please add any relevant lists and maintainers to the CCs when 
replying
> >> to this mail.
> > 
------------------------------------------------------------------------
> > 
> > agreed it ?
> 
>    No, I don't agree.
> 

So far, Jones seems don't agree RPC-IF to MFD and then RPC MFD will not 
applied
to mfd tree by him ! 

> [...]
> > thanks & best regards,
> > Mason
> 
> MBR, Sergei

thanks & best regards,
Mason

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