Messages in this thread Patch in this message |  | | From | Bhupesh Sharma <> | | Subject | [PATCH v2] coresight: etm4x: Fix crash observed on Qcom ETM parts with 'Low power override' | | Date | Thu, 25 Aug 2022 10:52:32 +0530 |
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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 <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> --- - v1 can be seen here: https://lore.kernel.org/lkml/20220803191236.3037591-1-bhupesh.sharma@linaro.org/ - Addressed the review comments from Suzuki. - Rebased on linux-next.
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..14c1c7869795 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -977,6 +977,16 @@ static bool etm4_init_sysreg_access(struct etmv4_drvdata *drvdata, if (!cpu_supports_sysreg_trace()) return false; + /* + * 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; + /* * ETMs implementing sysreg access must implement TRCDEVARCH. */ @@ -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
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