Re: [PATCHv3 3/4] coresight: etm4x: Add support to enable ETMv4.2

[Sai Prakash Ranjan]

On 1/22/2019 3:07 AM, Mathieu Poirier wrote:
> On Mon, 21 Jan 2019 at 11:48, Mathieu Poirier
> <mathieu.poirier@xxxxxxxxxx> wrote:
> > On Mon, Jan 21, 2019 at 04:18:36PM +0530, Vivek Gautam wrote:
> > > On 1/18/2019 5:52 PM, Sai Prakash Ranjan wrote:
> > > > SDM845 has ETMv4.2 and can use the existing etm4x driver.
> > > > But the current etm driver checks only for ETMv4.0 and
> > > > errors out for other etm4x versions. This patch adds this
> > > > missing support to enable SoC's with ETMv4x to use same
> > > > driver by checking only the ETM architecture major version
> > > > number.
> > > >
> > > > Without this change, we get below error during etm probe:
> > > >
> > > > / # dmesg | grep etm
> > > > [    6.660093] coresight-etm4x: probe of 7040000.etm failed with error -22
> > > > [    6.666902] coresight-etm4x: probe of 7140000.etm failed with error -22
> > > > [    6.673708] coresight-etm4x: probe of 7240000.etm failed with error -22
> > > > [    6.680511] coresight-etm4x: probe of 7340000.etm failed with error -22
> > > > [    6.687313] coresight-etm4x: probe of 7440000.etm failed with error -22
> > > > [    6.694113] coresight-etm4x: probe of 7540000.etm failed with error -22
> > > > [    6.700914] coresight-etm4x: probe of 7640000.etm failed with error -22
> > > > [    6.707717] coresight-etm4x: probe of 7740000.etm failed with error -22
> > > >
> > > > With this change, etm probe is successful:
> > > >
> > > > / # dmesg | grep coresight
> > > > [    6.659198] coresight-etm4x 7040000.etm: CPU0: ETM v4.2 initialized
> > > > [    6.665848] coresight-etm4x 7140000.etm: CPU1: ETM v4.2 initialized
> > > > [    6.672493] coresight-etm4x 7240000.etm: CPU2: ETM v4.2 initialized
> > > > [    6.679129] coresight-etm4x 7340000.etm: CPU3: ETM v4.2 initialized
> > > > [    6.685770] coresight-etm4x 7440000.etm: CPU4: ETM v4.2 initialized
> > > > [    6.692403] coresight-etm4x 7540000.etm: CPU5: ETM v4.2 initialized
> > > > [    6.699024] coresight-etm4x 7640000.etm: CPU6: ETM v4.2 initialized
> > > > [    6.705646] coresight-etm4x 7740000.etm: CPU7: ETM v4.2 initialized
> > > >
> > > > Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> > > > ---
> > > >    drivers/hwtracing/coresight/coresight-etm4x.c | 2 +-
> > > >    drivers/hwtracing/coresight/coresight-etm4x.h | 2 +-
> > > >    2 files changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> > > > index 53e2fb6e86f6..93d5f1f3145e 100644
> > > > --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> > > > +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> > > > @@ -55,7 +55,7 @@ static void etm4_os_unlock(struct etmv4_drvdata *drvdata)
> > > >    static bool etm4_arch_supported(u8 arch)
> > > >    {
> > > > -   switch (arch) {
> > > > +   switch (arch >> 4) {
> > >
> > >
> > > While this looks good, from what it looks like arch is a combination of
> > > major version
> > > minor version. So, will it be better to masks, and shifts macros instead of
> > > a magic
> > > number shift.
> > > But, frankly it's upto Mathieu to decide the readability of this. So, I
> > > leave it to him.
> >
> > The layout of the architecture is already well defined in etm4_init_arch_data()
> > [1].  As such just doing the following would be fine with me:
> >
> >          /* Mask out the minor version nuber */
> >          switch (arch & 0xf) {
>
> s/0xf/0xf0
>
> Apologies for the confusion.

Thanks Mathieu, made this change in v4 of this series.

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