On Sep 3, 2014, at 9:55 AM, Bjorn Andersson <[email protected]> wrote:
> On Wed 03 Sep 05:49 PDT 2014, Kumar Gala wrote: > >> >> On Sep 2, 2014, at 3:04 PM, Bjorn Andersson <[email protected]> >> wrote: >> >>> Changes since v2: >>> - MODULE_DEVICE_TABLE >>> - Changed prefix to qcom >>> - Cleaned up includes >>> - Rely on reg and num-locks to figure out stride, instead of of_match data >> >> I know Jeff prefers this method of computing stride, but I’m not a fan as >> there isn’t a reason one could adjust qcom,num-locks in the dt for some >> reason and leave regs alone. >> > > All the current platform it's 32 consecutive mutexes with either 4 or 128 byte > stride, so encoding it as data either way works fine. The hardware you're > trying to describe with your dt is the addresses that spans your mutex > registers and how many there are. So from the HW/dts pov I don't see why you > would like to do this. > > Then looking in the caf code, there is a limit of max 8 mutexes. So apparently > there is some sort of usecase, I just don't know what or if it's valid from a > dt pov. I believe not all the mutexes are meant for the cores running linux. However, I think we just expect linux to play nice and not touch anything it isn’t using explicitly. > Going to that future awesome SoCs where it's still called tcsr-mutex, but with > a stride of 4096 bytes makes me wonder; is that really a consecutive 128kb > with > nothing else in-between that we can ioremap? think 64-bit machines with more address space to burn and wanting to separate resources to use MMUs for protection. > I.e. can we really reuse this driver straight off for that SoC? I dont see why not. >>> diff --git a/Documentation/devicetree/bindings/hwlock/qcom-hwspinlock.txt >>> b/Documentation/devicetree/bindings/hwlock/qcom-hwspinlock.txt >>> +- compatible: >>> + Usage: required >>> + Value type: <string> >>> + Definition: must be one of: >>> + "qcom,sfpb-mutex", >>> + "qcom,tcsr-mutex” >> >> I dont get the purpose of having different compatible strings if there is no >> difference in the code between them. >> > > The semantics are the same, but there are no mutex registers in the tcsr block > in e.g 8960, so the name is just missleading. I assume that's why you didn't > follow caf and used the compatible "sfpb" in the first place? What do you expect the 8960 dt node to look like? I’m not 100% against ‘sfpb’ I’m feel like we we should use compat for stride, so we’d end up with something like: qcom,sfpb-mutex: stride 4 bytes, base: 0x01200604, reset: 0x01200600 qcom,tcsr-mutex: stride 128 bytes, base: 0xFD484000, reset: 0xFD485380 qcom,tcsr-4k-mutex: stride 4k bytes, base: 0x740000, reset: 0x767000 - k -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
