Hi Heiko/Uffe, > -----Original Message----- > From: Heiko Stuebner <heiko@xxxxxxxxx> > Sent: Thursday, August 22, 2019 11:53 PM > To: Ulf Hansson <ulf.hansson@xxxxxxxxxx>; linux-mmc@xxxxxxxxxxxxxxx > Cc: Manish Narani <MNARANI@xxxxxxxxxx>; Rob Herring <robh@xxxxxxxxxx>; > mark.rutland@xxxxxxx; Michal Simek <michals@xxxxxxxxxx>; > adrian.hunter@xxxxxxxxx; christoph.muellner@xxxxxxxxxxxxxxxxxxxxx; > philipp.tomsich@xxxxxxxxxxxxxxxxxxxxx; viresh.kumar@xxxxxxxxxx; > scott.branden@xxxxxxxxxxxx; ayaka@xxxxxxxxxxx; kernel@xxxxxxxx; > tony.xie@xxxxxxxxxxxxxx; Rajan Vaja <RAJANV@xxxxxxxxxx>; > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm- > kernel@xxxxxxxxxxxxxxxxxxx; linux-rockchip@xxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 01/11] dt-bindings: mmc: arasan: Update > documentation for SD Card Clock > > Am Donnerstag, 22. August 2019, 15:38:26 CEST schrieb Ulf Hansson: > > [...] > > > > > > > > > --- > > > > > > > Documentation/devicetree/bindings/mmc/arasan,sdhci.txt | 15 > > > > ++++++++++- > > > > > > ---- > > > > > > > 1 file changed, 10 insertions(+), 5 deletions(-) > > > > > > > > > > > > > > diff --git > a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > > > > > > b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > > > > > > > index 1edbb04..15c6397 100644 > > > > > > > --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > > > > > > > +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt > > > > > > > @@ -23,6 +23,10 @@ Required Properties: > > > > > > > - reg: From mmc bindings: Register location and length. > > > > > > > - clocks: From clock bindings: Handles to clock inputs. > > > > > > > - clock-names: From clock bindings: Tuple including "clk_xin" and > > > > "clk_ahb" > > > > > > > + Apart from these two there is one more optional clock > which > > > > > > > + is "clk_sdcard". This clock represents output clock from > > > > > > > + controller and card. This must be specified when #clock- > cells > > > > > > > + is specified. > > > > > > > - interrupts: Interrupt specifier > > > > > > > > > > > > > > Required Properties for "arasan,sdhci-5.1": > > > > > > > @@ -36,9 +40,10 @@ Optional Properties: > > > > > > > - clock-output-names: If specified, this will be the name of the card > > > > clock > > > > > > > which will be exposed by this device. Required if #clock-cells is > > > > > > > specified. > > > > > > > - - #clock-cells: If specified this should be the value <0>. With this > > > > property > > > > > > > - in place we will export a clock representing the Card Clock. This > clock > > > > > > > - is expected to be consumed by our PHY. You must also specify > > > > > > > + - #clock-cells: If specified this should be the value <0>. With this > > > > > > > + property in place we will export one clock representing the Card > > > > > > > + Clock. This clock is expected to be consumed by our PHY. You > must > > > > also > > > > > > > + specify > > > > > > > > > > > > specify what? > > > > > I think this line was already there, I missed to correct it, Will update in > v3. > > > > > > > > > > > > > > > > > The 3rd clock input I assume? This statement means any existing users > > > > > > with 2 clock inputs and #clock-cells are in error now. Is that correct? > > > > > Yes, this is correct. So far there was only one vendor using '#clock-cells' > > > > which is Rockchip. I have sent DT patch (02/11) for that also. > > > > > Here this is needed as earlier implementation isn't correct as suggested > by > > > > Uffe. (https://lkml.org/lkml/2019/6/20/486) . > > > > > > > > I am not sure how big of a problem the backwards compatible thingy > > > > with DT is, in general we must not break it. What do you say Manish? > > > > > > Though I agree with Uffe on this, there is no other way from my > understanding. Please suggest. > > > > > > > > > > > As a workaround, would it be possible to use > > > > of_clk_get_from_provider() somehow to address the compatibility issue? > > > > > > For this to be used we have to parse 'clkspec' from the DT node and pass > the same as an argument to this function. In this case also the DT node needs to > be updated, which is same as we have done in this series. > > > > Alright. I guess breaking DTBs for Rockchip platforms isn't > > acceptable, especially if those are already widely deployed, which I > > have no idea of.... > > The arasan sdhci is part of the rk3399, so every SBC using that SoC, but > also the whole Gru series of ChromeOS devices (Samsung Chromebook Plus > among them) would be affected. Thanks for confirming. This will be taken care of. I will go back to v1 changes and will send v3. Thanks, Manish
