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Message-ID: <20131009214638.GB2322@kartoffel> Date: Wed, 9 Oct 2013 22:46:38 +0100 From: Mark Rutland <mark.rutland@....com> To: Suman Anna <s-anna@...com> Cc: Kumar Gala <galak@...eaurora.org>, Ohad Ben-Cohen <ohad@...ery.com>, Tony Lindgren <tony@...mide.com>, Benoit Cousson <bcousson@...libre.com>, Paul Walmsley <paul@...an.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>, "devicetree@...r.kernel.org" <devicetree@...r.kernel.org> Subject: Re: [PATCHv2 2/9] hwspinlock/omap: add support for dt nodes On Thu, Oct 03, 2013 at 05:12:15AM +0100, Suman Anna wrote: > Hi Mark, > > > On Fri, Sep 27, 2013 at 05:06:38PM +0100, Kumar Gala wrote: > >> > >> On Sep 17, 2013, at 2:30 PM, Suman Anna wrote: > >> > >>> HwSpinlock IP is present only on OMAP4 and other newer SoCs, > >>> which are all device-tree boot only. This patch adds the > >>> base support for parsing the DT nodes, and removes the code > >>> dealing with the traditional platform device instantiation. > >>> > >>> Signed-off-by: Suman Anna <s-anna@...com> > >>> --- > >>> .../devicetree/bindings/hwlock/omap-hwspinlock.txt | 31 +++++++++++ > >>> arch/arm/mach-omap2/Makefile | 3 -- > >>> arch/arm/mach-omap2/hwspinlock.c | 60 ---------------------- > >>> drivers/hwspinlock/omap_hwspinlock.c | 23 +++++++-- > >>> 4 files changed, 50 insertions(+), 67 deletions(-) > >>> create mode 100644 Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt > >>> delete mode 100644 arch/arm/mach-omap2/hwspinlock.c > >>> > >>> diff --git a/Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt b/Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt > >>> new file mode 100644 > >>> index 0000000..235b7c5 > >>> --- /dev/null > >>> +++ b/Documentation/devicetree/bindings/hwlock/omap-hwspinlock.txt > >>> @@ -0,0 +1,31 @@ > >>> +OMAP4+ HwSpinlock Driver > >>> +======================== > >>> + > >>> +Required properties: > >>> +- compatible: Currently supports only "ti,omap4-hwspinlock" for > >>> + OMAP44xx, OMAP54xx, AM33xx, AM43xx, DRA7xx SoCs > > > > "Currently supports" is not something I expect to see in a binding > > document. That sounds like a description of the driver rather than the > > binding. > > > > How similar are these hardware modules? What are the differences? > > The IP is almost the same, they all have the same revision id. The > number of locks (each represented by a register) though vary from one > SoC to another (OMAP4, OMAP5, DRA7 have same number of locks, and > AM33xx/AM43xx have a different number). The number of locks is directly > read by the driver from a module register. There is no separate .data > associated with the of_device_id table, so I used a single compatible > property for all the SoCs. Ok. Probeability is good, it keeps these simpler :) I think This can be reworded to say "should contain" rather than "currently supports only": - compatible: Should contain "ti,omap4-hwspinlock" for OMAP44xx, OMAP54xx, AM33xx, AM43xx, or DRA7xx SoCs That way the binding allows for a future backwards-compatible variant, and doesn't mention the current level of support in Linux. > > > > >>> +- reg: Contains the hwspinlock register address range (base > >>> + address and length) > > > > Is there only one register bank for the hwlock module? > > The lock registers start at a certain offset (0x800) within the module > register space, and the offsets for various registers are identical > between all SoCs. What are the other registers within the module? Are they shared with other devices, or are they simply unused by the hwspinlock driver? > > > > >>> +- ti,hwmods: Name of the hwmod associated with the hwspinlock device > >>> + > >>> +Common hwlock properties: > >>> +The following describes the usage of the common hwlock properties (defined in > >>> +Documentation/devicetree/bindings/hwlock/hwlock.txt) on OMAP. > >>> + > >>> +- hwlock-base-id: There are currently no OMAP SoCs with multiple > >>> + hwspinlock devices. The OMAP driver uses a default > >>> + base id value of 0 for the locks present within the > >>> + single hwspinlock device on all SoCs. > > > > > > Driver details should not leak into bindngs... > > OK, will remove the info on driver details. > > > > > As mentioned in the other patch, I don't think this is the way to handle > > this. I think we need a phandle + args representation. > > This is an optional parameter for now and I was going to revise the > description based on comments from Kumar Gala on this thread, but I will > wait and adjust this based on the outcome on the first patch. Ok. > > > > >>> +- hwlock-num-locks: This property is not required on OMAP SoCs, since the > >>> + number of locks present within a device can be deduced > >>> + from the SPINLOCK_SYSSTATUS device register. > > > > Huh? Why define this property at all here if we don't need it and don't > > use it? > > > > The common document should state that specific bindings may use it and > > should explicitly state if they do, rather than stating they don't... > > Yeah, I wasn't sure how to go about the split between the common file > and the platform-specific bindings. I will clean this up and revise the > common bindings. Ok. Cheers, Mark. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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