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.
Fixes: 5214b563588e ("coresight: etm4x: Add support for sysreg only devices")
Cc: Mike Leach <[email protected]>
Cc: Suzuki K Poulose <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Bhupesh Sharma <[email protected]>
---
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;
major = ETM_ARCH_MAJOR_VERSION(drvdata->arch);
--
2.35.3
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 <[email protected]>
> Cc: Suzuki K Poulose <[email protected]>
> Cc: Mathieu Poirier <[email protected]>
> Cc: Greg Kroah-Hartman <[email protected]>
> Signed-off-by: Bhupesh Sharma <[email protected]>
> ---
> 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);
Hi Suzuki,
On Thu, 4 Aug 2022 at 19:02, Suzuki K Poulose <[email protected]> wrote:
>
> 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 <[email protected]>
> > Cc: Suzuki K Poulose <[email protected]>
> > Cc: Mathieu Poirier <[email protected]>
> > Cc: Greg Kroah-Hartman <[email protected]>
> > Signed-off-by: Bhupesh Sharma <[email protected]>
> > ---
> > 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.
Sure, let me fix this in v2.
Regards,
Bhupesh
> > major = ETM_ARCH_MAJOR_VERSION(drvdata->arch);
>