Hi Bhupesh,

On 03/08/2022 20:12, Bhupesh Sharma wrote:

Some Qualcomm ETM implementations require skipping powering up the trace unit, as the ETMs are in the same power domain as their CPU cores.

Via commit 5214b563588e ("coresight: etm4x: Add support for sysreg only devices"), the setting of 'skip_power_up' flag was moved after the 'etm4_init_arch_data' function is called, whereas the flag value is itself used inside the function. This causes a crash when ETM mode 'Low-power state behavior override' is set on some Qualcomm parts.

Fix the same.

Thanks for the patch. The patch is correct. But please see my comment below.

Fixes: 5214b563588e ("coresight: etm4x: Add support for sysreg only devices") Cc: Mike Leach mike.leach@linaro.org Cc: Suzuki K Poulose suzuki.poulose@arm.com Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Bhupesh Sharma bhupesh.sharma@linaro.org

---

drivers/hwtracing/coresight/coresight-etm4x-core.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index d39660a3e50c..cf6254b87fd5 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -1943,6 +1943,16 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid) init_arg.csa = &desc.access; init_arg.pid = etm_pid;

• /*

• * Some Qualcomm implementations require skipping powering up the trace unit,
  

• * as the ETMs are in the same power domain as their CPU cores.
  

• *
  

• * Since the 'skip_power_up' flag is used inside 'etm4_init_arch_data' function,
  

• * initialize it before the function is called.
  

• */
  

• if (fwnode_property_present(dev_fwnode(dev), "qcom,skip-power-up"))

• drvdata->skip_power_up = true;
  

• if (smp_call_function_single(drvdata->cpu, etm4_init_arch_data, &init_arg, 1)) dev_err(dev, "ETM arch init failed\n");

@@ -1951,8 +1961,7 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid) return -EINVAL; /* TRCPDCR is not accessible with system instructions. */

• if (!desc.access.io_mem ||

•    fwnode_property_present(dev_fwnode(dev), "qcom,skip-power-up"))
  

• if (!desc.access.io_mem) drvdata->skip_power_up = true;

Please could you move this setting into "etm4_init_sysreg_access()" ? It looks a bit odd to split the check in the same function. Moving this to the sysreg_access() makes it explicit.

Suzuki

major = ETM_ARCH_MAJOR_VERSION(drvdata->arch);