Hi Magnus, Thank you for the patches. On Sunday 21 June 2015 17:09:03 Magnus Damm wrote: > clocksource: sh_cmt: DT binding rework > > [PATCH 01/08] devicetree: bindings: Remove sh7372 CMT binding > [PATCH 02/08] clocksource: sh_cmt: Use 0x3f mask for SH_CMT_48BIT case > [PATCH 03/08] devicetree: bindings: R-Car Gen2 CMT0 and CMT1 bindings > [PATCH 04/08] clocksource: sh_cmt: Support separate R-Car Gen2 CMT0/1 > [PATCH 05/08] devicetree: bindings: r8a73a4 and R-Car Gen2 CMT bindings > [PATCH 06/08] ARM: shmobile: Update CMT compat string users in DTS > [PATCH 07/08] devicetree: bindings: Deprecate property, update example > [PATCH 08/08] ARM: shmobile: Remove CMT renesas,channels-mask from DTS > > This series reworks the CMT DT bindings to try to deal with the following: > - R-Car Gen2 CMT0 and CMT1 hardware instances are not identical > - The property renesas,channels-mask is not enough to describe the > difference > - DT should describe the hardware, not the software implementation > - Not all documented DT bindings are actually used > > Without these patches the binding "renesas,cmt-48-gen2" is used for both > CMT0 and CMT1 on R-Car Gen2 SoCs. CMT0 and CMT1 are currently seen by the > Linux device driver as compatible hardware, and the device-specific property > "renesas,channels-mask" is used to point out some of the hardware > configuration differences. Since the driver is not feature complete only > some differences are described and when diving into the data sheet we can > see that: > > 1) CMT0 is not 48-bit at all, instead it only supports 32-bit counters. How the heck did we come up with these bindings in the first place ? > 2) Some channels of CMT1 are 48-bit, some 32-bit. > 3) A couple of CMT1 channels have even more features. > > It turns out that none of the above differences are described in our current > DT files. And since we use the same compat string for CMT0 and CMT1 the > driver itself cannot enable features specific only to CMT1 without first > updating the DTS. So this series is ground work for future feature patches. > > It seems that we have two choices if we want to support CMT1 features: > A) Keep existing DT bindings, add more properties for CMT1 > B) Rework the compatible strings and keep configuration in the driver > > Judging by above it seems that DT update is inevitable. In my mind it is > rather painful to update the DT so I'd like to minimize the number of > updates and let the majority of the changes only happen in the driver. > And since we should really describe hardware in DT but driver features tend > to be implemented incrementally then B) seems like a good fit to me. > > I wouldn't mind going with A) but to be honest I must say that the existing > compat string "renesas,cmt-48-gen2" is just too confusing with "48" > (when CMT0 is 32bit-only) and also "gen2" (used without product line R-Car). > > Because of that I've gone with B) and reworked the bindings to separate > CMT0 from CMT1 and keep channel configuration in the device driver. In this specific case B seems to be better given that the CMT features look quite random. We would need to encode too many properties in DT. > While at it I've deprecated "renesas,channels-mask" and the old DT compat > strings. Per-SoC compat strings have also been reworked, but are not left > around documented as deprecated since they were never used by the driver. Shouldn't we remove the renesas,channels-mask property completely from the documentation ? The git history could be considered as enough when it comes to documenting deprecated properties. > Comments are very welcome! If all are in favor then it would be good to > merge patch 1-5 first and patch 6-8 later once 1-5 are in. Old DTBs are > left working but treated as low-feature CMT0. New DTBs including patch 6-8 > will not work on old kernels. Apart from Geert's comments on patches 1/8 and 2/8, and my comment on patch 8/8, the series looks fine to me. With those problems fixed, Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > Signed-off-by: Magnus Damm <damm+renesas@xxxxxxxxxxxxx> > --- > > Written against renesas-devel-20150619-v4.1-rc8 > > Documentation/devicetree/bindings/timer/renesas,cmt.txt | 55 +++++++----- > arch/arm/boot/dts/r8a73a4.dtsi | 5 - > arch/arm/boot/dts/r8a7740.dtsi | 3 > arch/arm/boot/dts/r8a7790.dtsi | 10 -- > arch/arm/boot/dts/r8a7791.dtsi | 10 -- > arch/arm/boot/dts/r8a7793.dtsi | 10 -- > arch/arm/boot/dts/r8a7794.dtsi | 10 -- > arch/arm/boot/dts/sh73a0.dtsi | 3 > drivers/clocksource/sh_cmt.c | 54 ++++++++---- > 9 files changed, 83 insertions(+), 77 deletions(-) -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe devicetree" in
