Messages in this thread | | | Date | Thu, 27 Oct 2022 14:52:34 +0800 | Subject | Re: [PATCH 4/9] coresight-tpdm: Add reset node to TPDM node | From | Tao Zhang <> |
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Hi Suzuki,
在 10/24/2022 6:10 PM, Suzuki K Poulose 写道: > On 08/09/2022 09:45, Tao Zhang wrote: >> TPDM device need a node to reset the configurations and status of >> it. This change provides a node to reset the configurations and >> disable the TPDM if it has been enabled. > > It is not clear to me *why* this is needed. Please could you > elaborate on the use case of this ? See my questions below. For example, we usually reset the configuration through the "reset" node before using a TPDM, so as to avoid the previous configuration affecting the current use. And in some scenarios, it may be necessary to reset the TPDM configuration to complete the verification of certain function. >> >> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com> >> --- >> drivers/hwtracing/coresight/coresight-tpdm.c | 32 >> ++++++++++++++++++++++++++++ >> 1 file changed, 32 insertions(+) >> >> diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c >> b/drivers/hwtracing/coresight/coresight-tpdm.c >> index 69ea453..74cc653 100644 >> --- a/drivers/hwtracing/coresight/coresight-tpdm.c >> +++ b/drivers/hwtracing/coresight/coresight-tpdm.c >> @@ -152,6 +152,37 @@ static void tpdm_init_default_data(struct >> tpdm_drvdata *drvdata) >> } >> } >> +static ssize_t reset_store(struct device *dev, >> + struct device_attribute *attr, >> + const char *buf, >> + size_t size) > > minor nit: Alignment > I will update this in the next patch series. >> +{ >> + int ret = 0; >> + unsigned long val; >> + struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent); >> + >> + ret = kstrtoul(buf, 10, &val); > > So, any integer value written to the sysfs knob triggers the rest ? > It may be better to restrict this to "1". > Make sense, I will update this in the next patch series. > >> + if (ret) >> + return ret; >> + >> + spin_lock(&drvdata->spinlock); >> + /* Reset all datasets to ZERO */ >> + if (drvdata->dsb != NULL) >> + memset(drvdata->dsb, 0, sizeof(struct dsb_dataset)); >> + >> + /* Init the default data */ >> + tpdm_init_default_data(drvdata); > > Why is this needed ? Does the DSB device configuration change > on the fly ? > We usually reset the configuration through the "reset" node at the beginning of using a TPDM. DSB related elements need to be initialized before configuring them. The TPDM is usually to be used by the following sequence. Reset(initialization) -> Configure -> Enable to use >> + >> + spin_unlock(&drvdata->spinlock); >> + >> + /* Disable tpdm if enabled */ >> + if (drvdata->enable) >> + coresight_disable(drvdata->csdev); > > Why is this needed ? Isn't this supposed to be triggered from the "path" > when the trace session is complete ? > In some scenarios, it may be necessary to reset the TPDM configuration in the process of verification and re-configure the TPDM. If this is the case, we need to disable the TPDM first, and re-configure before enabling it again. > > Suzuki > >> + >> + return size; >> +} >> +static DEVICE_ATTR_WO(reset); >> + >> /* >> * value 1: 64 bits test data >> * value 2: 32 bits test data >> @@ -192,6 +223,7 @@ static ssize_t integration_test_store(struct >> device *dev, >> static DEVICE_ATTR_WO(integration_test); >> static struct attribute *tpdm_attrs[] = { >> + &dev_attr_reset.attr, >> &dev_attr_integration_test.attr, >> NULL, >> }; > Best Regards Tao
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