Messages in this thread | | | Date | Mon, 7 Nov 2022 16:44:13 +0000 | Subject | Re: [PATCH v2] coresight: etm4x: Fix crash observed on Qcom ETM parts with 'Low power override' | From | Suzuki K Poulose <> |
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Hi Bupesh, \ On 14/09/2022 15:43, Suzuki K Poulose wrote: > On 13/09/2022 11:52, Leo Yan wrote: >> Hi Bhupesh, >> >> On Thu, Aug 25, 2022 at 10:52:32AM +0530, 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. >>> >>> 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; >>> + >> >> I personally think this sentence should be placed in the function >> etm4_probe(), you need to move it just before smp call >> etm4_init_arch_data(), this can allow DT property "qcom,skip-power-up" >> to be respected. > > Or we could move this to init_iomem_access() and explicitly set the flag > to true in init_sysreg_access(). > >> >>> /* >>> * 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; >> >> I prefer to move the condition checking for "desc.access.io_mem" to >> etm4_init_sysreg_access(), this can make sure the flag skip_power_up >> is set correctly based on property of system register access. > > +1 >
Do you plan to send an updated patch for this one ?
Kind regards Suzuki
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