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

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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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