From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Fabrizio Castro Subject: RE: [PATCH 1/6] dt-bindings: mmc: renesas_sdhi: Add r8a77470 support Date: Thu, 4 Oct 2018 10:37:52 +0000 Message-ID: References: <1538564744-15590-1-git-send-email-fabrizio.castro@bp.renesas.com> <1538564744-15590-2-git-send-email-fabrizio.castro@bp.renesas.com> <20181004095955.qhltoiybmdd23lfx@verge.net.au> In-Reply-To: <20181004095955.qhltoiybmdd23lfx@verge.net.au> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 To: Simon Horman Cc: Ulf Hansson , Rob Herring , Geert Uytterhoeven , Mark Rutland , "linux-mmc@vger.kernel.org" , "devicetree@vger.kernel.org" , Chris Paterson , Biju Das , "linux-renesas-soc@vger.kernel.org" List-ID: Hello Simon, Thank you for your feedback! > Subject: Re: [PATCH 1/6] dt-bindings: mmc: renesas_sdhi: Add r8a77470 sup= port > > On Wed, Oct 03, 2018 at 12:05:39PM +0100, Fabrizio Castro wrote: > > The RZ/G1C (a.k.a. R8A77470) comes with three SDHI interfaces, > > SDHI0 and SDHI2 are compatible with R-Car Gen2 SDHIs, and > > SDHI1 is compatible with R-Car Gen3 SDHIs, as it comes with an > > internal DMAC, therefore SDHI1 is fully compatible with driver > > renesas_sdhi_internal_dmac driver. As a result, the compatible > > strings for the R8A77470 SDHI interfaces are a little bit special. > > Document SDHI support for the RZ/G1C SoC. > > > > Signed-off-by: Fabrizio Castro > > Reviewed-by: Biju Das > > > > --- > > v1->v2: > > * Added "renesas,sdhi-mmc-r8a77470" > > * Using generic/fallback compatibilty only for SDHI[02] > > * Reworked changelog > > --- > > Documentation/devicetree/bindings/mmc/tmio_mmc.txt | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/devicetree/bindings/mmc/tmio_mmc.txt b/Docum= entation/devicetree/bindings/mmc/tmio_mmc.txt > > index d39d5e4..247abee 100644 > > --- a/Documentation/devicetree/bindings/mmc/tmio_mmc.txt > > +++ b/Documentation/devicetree/bindings/mmc/tmio_mmc.txt > > @@ -19,6 +19,8 @@ Required properties: > > "renesas,sdhi-r8a7744" - SDHI IP on R8A7744 SoC > > "renesas,sdhi-r8a7745" - SDHI IP on R8A7745 SoC > > "renesas,sdhi-r8a774a1" - SDHI IP on R8A774A1 SoC > > +"renesas,sdhi-r8a77470" - SDHI IP on R8A77470 SoC (SDHI[02]) > > +"renesas,sdhi-mmc-r8a77470" - SDHI IP on R8A77470 SoC (SDHI1) > > I understand that SDHI[02] is different to SDHI1 on this SoC. > But I'm not clear on why SDHI1 is more "mmc" than SDHI[02]. Only SDHI1 can be used as MMC interface, from Section 40.1.1 of the SD Card manual: " This LSI has three SD card interfaces (SDHI0 to SDHI2), one of wh= ich can also be used as MMC interfaces (SDHI1)." > > > "renesas,sdhi-r8a7778" - SDHI IP on R8A7778 SoC > > "renesas,sdhi-r8a7779" - SDHI IP on R8A7779 SoC > > "renesas,sdhi-r8a7790" - SDHI IP on R8A7790 SoC > > @@ -35,8 +37,8 @@ Required properties: > > "renesas,sdhi-r8a77995" - SDHI IP on R8A77995 SoC > > "renesas,sdhi-shmobile" - a generic sh-mobile SDHI controller > > "renesas,rcar-gen1-sdhi" - a generic R-Car Gen1 SDHI controller > > -"renesas,rcar-gen2-sdhi" - a generic R-Car Gen2 or RZ/G1 > > - SDHI controller > > +"renesas,rcar-gen2-sdhi" - a generic R-Car Gen2 and RZ/G1 (but > > + not RZ/G1C SDHI1) SDHI controller > > "renesas,rcar-gen3-sdhi" - a generic R-Car Gen3 or RZ/G2 > > SDHI controller > > renesas,rcar-gen3-sdhi can be used with RZ/G1C SDHI1, right? It can be used, but when we previously discussed about this I have received= bad feedbacks from both yourself and Geert: Geert: "I'm a bit reluctant to add "renesas,rcar-gen3-sdhi", though" You: "I am also reluctant to add "renesas,rcar-gen3-sdhi", because as we ar= e seeing things are not so simple wrt to compatible." We need to make a final decision here, but automatically detecting the IP d= oesn't seem to be great, so the final solution has to rely on compatible strings. > The naming is starting to break down at this point :( Personally, I am not too bothered about using "renesas,rcar-gen3-sdhi" for this specific IP, as this chip "borrows" Gen3 implementation, but of co= urse it exposes some cross compatibility with other families of products which coul= d result in some confusion to the final user. Anyway, as long as we document things pro= perly there should be no confusion. Thanks, Fab > > > > > -- > > 2.7.4 > > Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, B= uckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered= No. 04586709.