On 04/23/2015 11:16 AM, Mathieu Poirier wrote: > On 23 April 2015 at 09:08, Christopher Covington <c...@codeaurora.org> wrote: >> Hi Mathieu, >> >> On 04/22/2015 06:40 PM, Mathieu Poirier wrote: >>> From: Pratik Patel <prat...@codeaurora.org> >>> >>> Adding sysfs entries to access and configure specifics about the >>> context ID comparator functions. >>> >>> Signed-off-by: Pratik Patel <prat...@codeaurora.org> >>> Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org> >>> --- >>> .../ABI/testing/sysfs-bus-coresight-devices-etm4x | 19 +++ >>> drivers/hwtracing/coresight/coresight-etm4x.c | 187 >>> +++++++++++++++++++++ >>> 2 files changed, 206 insertions(+) >>> >>> diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x >>> b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x >>> index b5c0456290ab..8b32cb7b9723 100644 >>> --- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x >>> +++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x >>> @@ -254,3 +254,22 @@ Date: April 2015 >>> KernelVersion: 4.01 >>> Contact: Mathieu Poirier <mathieu.poir...@linaro.org> >>> Description: (RW) Controls the selection of the resources in the >>> trace unit. >>> + >>> +What: /sys/bus/coresight/devices/<memory_map>.etm/ctxid_idx >>> +Date: April 2015 >>> +KernelVersion: 4.01 >>> +Contact: Mathieu Poirier <mathieu.poir...@linaro.org> >>> +Description: (RW) Select which context ID comparator to work with. >>> + >>> +What: /sys/bus/coresight/devices/<memory_map>.etm/ctxid_val >>> +Date: April 2015 >>> +KernelVersion: 4.01 >>> +Contact: Mathieu Poirier <mathieu.poir...@linaro.org> >>> +Description: (RW) Get/Set the context ID comparator value to trigger on. >> >> If I'm understanding this correctly, ctxid_val is multiplexed using >> ctxid_idx. >> Why not just have ctxid_val0, ctxid_val1, ...? > > There can be up to 8 of them on the current implementation and who > knows how many more in the future. To me using and index to select > the context ID to work on scaled better and is introducing less > clutter in sysfs.
In theory there's a race condition if two tasks are trying to set the index and then the value, which having individually addressable values solves, but I don't anticipate trying to use more than one task to configure tracing. Chris -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
