Re: [PATCH v2 3/4] coresight: etm3x: Deal with CLAIM tag before and after accessing HW

[Suzuki K Poulose]

Hi,

On 07/11/2018 23:08, Mathieu Poirier wrote:

This patch moves access to the CLAIM tag so that no modification to the HW
happens before and after the CLAIM operation has been carried.

Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
---
  drivers/hwtracing/coresight/coresight-etm3x.c | 16 ++++++++--------
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c 
b/drivers/hwtracing/coresight/coresight-etm3x.c
index fd5c4cca7db5..4f638d81a66a 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -363,15 +363,16 @@ static int etm_enable_hw(struct etm_drvdata *drvdata)

CS_UNLOCK(drvdata->base); + rc = coresight_claim_device_unlocked(drvdata->base);

+       if (rc)
+               goto done;
+
        /* Turn engine on */
        etm_clr_pwrdwn(drvdata);
        /* Apply power to trace registers */
        etm_set_pwrup(drvdata);
        /* Make sure all registers are accessible */
        etm_os_unlock(drvdata);
-       rc = coresight_claim_device_unlocked(drvdata->base);
-       if (rc)
-               goto done;

etm_set_prog(drvdata); @@ -422,12 +423,11 @@ static int etm_enable_hw(struct etm_drvdata *drvdata)

        etm_clr_prog(drvdata);

done:

-       if (rc)
-               etm_set_pwrdwn(drvdata);
        CS_LOCK(drvdata->base);

- dev_dbg(drvdata->dev, "cpu: %d enable smp call done: %d\n",

-               drvdata->cpu, rc);
+       if (!rc)
+               dev_dbg(drvdata->dev, "cpu: %d enable smp call done: %d\n",
+                       drvdata->cpu, rc);

Isn't it good to report the failure case too ? Anyway it is dev_dbg and
will be a useful info when we debug issues. Otherwise,

Reviewed-by: Suzuki K Poulose <suzuki.poul...@arm.com>

        return rc;
  }

@@ -577,9 +577,9 @@ static void etm_disable_hw(void *info)

        for (i = 0; i < drvdata->nr_cntr; i++)
                config->cntr_val[i] = etm_readl(drvdata, ETMCNTVRn(i));

+ etm_set_pwrdwn(drvdata);

        coresight_disclaim_device_unlocked(drvdata->base);

- etm_set_pwrdwn(drvdata);

        CS_LOCK(drvdata->base);

dev_dbg(drvdata->dev, "cpu: %d disable smp call done\n", drvdata->cpu);