Hi Mason, Note that if you send multipart/text+html emails, they will be dropped silently by most Linux mailing lists. Hence I'm quoting your last email fully, to give other people a chance reading it (and commenting). On Mon, May 13, 2019 at 11:37 AM <masonccyang@xxxxxxxxxxx> 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@xxxxxxxxxxx> > > > > >> > >> > >> --- > > > > >> > >> > >> .../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-compliantflash 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@xxxxxxxxxxxxx> > > > > >> > > > > >> 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. > > > > > So far, Jones seems don't agree RPC-IF to MFD and then RPC MFD > > will not applied > > > to mfd tree by him ! > > > > There's precedence for such constructs being an MFD: please see > > drivers/mfd/at91-usart.c, which registers a single MFD cell for either > > serial or SPI. > > okay, many thanks for your information. > > How about to patch RPF-IF dts to: > --------------------------------------------------------------> > > Renesas R-Car Gen3 RPC-IF controller Device Tree Bindings > --------------------------------------------------------- > > RPC-IF supports both SPI NOR and HyperFlash (CFI-compliant flash) > > Required properties: > - compatible: should be an SoC-specific compatible value, followed by > "renesas,rcar-gen3-rpc" as a fallback. > supported SoC-specific values are: > "renesas,r8a77995-rpc" (R-Car D3) > - reg: should contain three register areas: > first for the base address of RPC-IF registers, > second for the direct mapping read mode and > third for the write buffer area. > - reg-names: should contain "regs", "dirmap" and "wbuf" > - clocks: should contain 1 entries for the module's clock > - clock-names: should contain "rpc" > > Example: > - SPI mode: > > rpc: rpc-if@ee200000 { > compatible = "renesas,r8a77995-rpc", "renesas,rcar-gen3-rpc"; > reg = <0 0xee200000 0 0x200>, <0 0x08000000 0 0x4000000>, > <0 0xee208000 0 0x100>; > reg-names = "regs", "dirmap", "wbuf"; > clocks = <&cpg CPG_MOD 917>; > clock-names = "rpc"; > power-domains = <&sysc R8A77995_PD_ALWAYS_ON>; > resets = <&cpg 917>; > #address-cells = <1>; > #size-cells = <0>; > > flash@0 { > compatible = "jedec,spi-nor"; > reg = <0>; > spi-max-frequency = <40000000>; > spi-tx-bus-width = <1>; > spi-rx-bus-width = <1>; > }; > }; > > - HF mode: > rpc: rpc-if@ee200000 { > compatible = "renesas,r8a77995-rpc", "renesas,rcar-gen3-rpc"; > reg = <0 0xee200000 0 0x200>, <0 0x08000000 0 0x4000000>, > <0 0xee208000 0 0x100>; > reg-names = "regs", "dirmap", "wbuf"; > clocks = <&cpg CPG_MOD 917>; > clock-names = "rpc"; > power-domains = <&sysc R8A77995_PD_ALWAYS_ON>; > resets = <&cpg 917>; > #address-cells = <1>; > #size-cells = <1>; > > flash@0 { > compatible = "cfi-flash"; > reg = <0 0x4000000>; > }; > }; > > --------------------------------------------------------------< > > Is it OK ? I'll defer to the MTD experts. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
