Messages in this thread | | | Date | Wed, 14 Sep 2022 23:00:39 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v2] coresight: etm4x: Fix crash observed on Qcom ETM parts with 'Low power override' |
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On Wed, Sep 14, 2022 at 03:43:53PM +0100, Suzuki Kuruppassery Poulose wrote:
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> > > + /* > > > + * 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().
Agreed, this is more clear.
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> > A side topic, in the mainline kernel I found the value > > "desc.access.io_mem" is always zero (see the initialized value in > > etm4_probe() and etm4_init_sysreg_access()). Should we initialize > > desc.access.io_mem to true in etm4_probe()? > > Thats not true. It is initialised at : > > etm4_init_iomem_access(): > > *csa = CSDEV_ACCESS_IOMEM(drvdata->base); > > Where > > #define CSDEV_ACCESS_IOMEM(_addr) \ > ((struct csdev_access) { \ > .io_mem = true, \ > .base = (_addr), \ > })
Thanks a lot for explaination, sorry for noise.
Leo
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