Hi suzuki, On Thu, 24 Sep 2020 at 10:43, Suzuki K Poulose <suzuki.poulose@xxxxxxx> wrote: > > On 09/18/2020 04:35 PM, Mike Leach wrote: > > On Fri, 11 Sep 2020 at 09:41, Suzuki K Poulose <suzuki.poulose@xxxxxxx> wrote: > >> > >> Document the bindings for ETMv4.4 and later with only system register > >> access. > >> > >> Cc: devicetree@xxxxxxxxxxxxxxx > >> Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> > >> Cc: Mike Leach <mike.leach@xxxxxxxxxx> > >> Reviewed-by: Rob Herring <robh@xxxxxxxxxx> > >> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> > >> --- > >> Documentation/devicetree/bindings/arm/coresight.txt | 6 +++++- > >> 1 file changed, 5 insertions(+), 1 deletion(-) > >> > >> diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt > >> index d711676b4a51..cfe47bdda728 100644 > >> --- a/Documentation/devicetree/bindings/arm/coresight.txt > >> +++ b/Documentation/devicetree/bindings/arm/coresight.txt > >> @@ -34,9 +34,13 @@ its hardware characteristcs. > >> Program Flow Trace Macrocell: > >> "arm,coresight-etm3x", "arm,primecell"; > >> > >> - - Embedded Trace Macrocell (version 4.x): > >> + - Embedded Trace Macrocell (version 4.x), with memory mapped access. > >> "arm,coresight-etm4x", "arm,primecell"; > >> > >> + - Embedded Trace Macrocell (version 4.4 and later) with system > >> + register access only. > >> + "arm,coresight-etm-v4.4"; > > > > Any version of ETM can implement register access - including those pre > > ETM 4.4. Perhaps the new name should simply reflect sys reg access > > rather than a version. > > > > You're right. I got it confused with the v8.4 SelfHosted Extensions, which > mandates the sysreg access and makes the mem I/O obsolete. How about : > > "arm,coresight-etm4x-sysreg" ? > > Seems reasonable. Perhaps ensure that the accompanying comment mentions that this is aarch64 access (to cover the unlikely event that some outlier implementation does come along with v8 aarch32 + ETMv4 + sysreg access!) > > Given that the two compatibility strings should be mutually exclusive > > for a given device, should the bindings doc (or at least the etm4x > > component part) be re-written into the .yaml format so that this can > > be enforced? > > I will take a look, haven't played with the yaml. > I used it to describe the CTI bindings as these were brand new. Reasonably straight forwards - there are plenty of examples and the checking tools are pretty good. Regards Mike > Thanks for the review ! > > Suzuki -- Mike Leach Principal Engineer, ARM Ltd. Manchester Design Centre. UK
