Re: [PATCH v2 2/6] coresight: Fail to open with return stacks if they are unavailable

Reviewed-by: Mike Leach mike.leach@linaro.org

On Thu, 13 Jan 2022 at 09:11, James Clark james.clark@arm.com wrote:

Maintain consistency with the other options by failing to open when they aren't supported. For example ETM_OPT_TS, ETM_OPT_CTXTID2 and the newly added ETM_OPT_BRANCH_BROADCAST all return with -EINVAL if they are requested but not supported by hardware.

The consequence of not doing this is that the user may not be aware that they are not enabling the feature as it is silently disabled.

Signed-off-by: James Clark james.clark@arm.com

drivers/hwtracing/coresight/coresight-etm4x-core.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 04669ecc0efa..a93c1a5fe045 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -674,10 +674,15 @@ static int etm4_parse_event_config(struct coresight_device *csdev, }

    /* return stack - enable if selected and supported */

•   if ((attr->config & BIT(ETM_OPT_RETSTK)) && drvdata->retstack)
  

•           /* bit[12], Return stack enable bit */
  

•           config->cfg |= BIT(12);
  

•   if (attr->config & BIT(ETM_OPT_RETSTK)) {
  

•           if (!drvdata->retstack) {
  

•                   ret = -EINVAL;
  

•                   goto out;
  

•           } else {
  

•                   /* bit[12], Return stack enable bit */
  

•                   config->cfg |= BIT(12);
  

•           }
  

•   }
    /*
     * Set any selected configuration and preset.
     *
  

-- 2.28.0