| Message ID | 20230803055652.1322801-4-anshuman.khandual@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | coresight: trbe: Enable ACPI based devices | expand |
On 03/08/2023 06:56, Anshuman Khandual wrote: > TRBE coresight devices do not need regular connections information, as the > paths get built between all percpu source and their respective percpu sink > devices. Please refer 'commit 2cd87a7b293d ("coresight: core: Add support > for dedicated percpu sinks")' which added support for percpu sink devices. > > coresight_register() expect device connections via the platform_data. TRBE > devices do not have any graph connections and thus is empty. With upcoming > ACPI support for TRBE, we do not get a real acpi_device and thus > coresight_get_platform_dat() will end up in failures. Hence this allocates > a zeroed coresight_platform_data structure and assigns that back into the > device. > > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > Cc: Mike Leach <mike.leach@linaro.org> > Cc: Leo Yan <leo.yan@linaro.org> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> > Cc: coresight@lists.linaro.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > drivers/hwtracing/coresight/coresight-trbe.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index 7720619909d6..e1d9d06e7725 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -1494,9 +1494,9 @@ static int arm_trbe_device_probe(struct platform_device *pdev) > if (!drvdata) > return -ENOMEM; > > - pdata = coresight_get_platform_data(dev); > - if (IS_ERR(pdata)) > - return PTR_ERR(pdata); > + pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); > + if (!pdata) > + return -ENOMEM; Please could you add a comment in here, on why we use a dummy platform data ? It is good to have documented it in the code too. Suzuki > > dev_set_drvdata(dev, drvdata); > dev->platform_data = pdata;
On 8/3/23 19:25, Suzuki K Poulose wrote: > On 03/08/2023 06:56, Anshuman Khandual wrote: >> TRBE coresight devices do not need regular connections information, as the >> paths get built between all percpu source and their respective percpu sink >> devices. Please refer 'commit 2cd87a7b293d ("coresight: core: Add support >> for dedicated percpu sinks")' which added support for percpu sink devices. >> >> coresight_register() expect device connections via the platform_data. TRBE >> devices do not have any graph connections and thus is empty. With upcoming >> ACPI support for TRBE, we do not get a real acpi_device and thus >> coresight_get_platform_dat() will end up in failures. Hence this allocates >> a zeroed coresight_platform_data structure and assigns that back into the >> device. >> >> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> >> Cc: Mike Leach <mike.leach@linaro.org> >> Cc: Leo Yan <leo.yan@linaro.org> >> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> >> Cc: coresight@lists.linaro.org >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >> --- >> drivers/hwtracing/coresight/coresight-trbe.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c >> index 7720619909d6..e1d9d06e7725 100644 >> --- a/drivers/hwtracing/coresight/coresight-trbe.c >> +++ b/drivers/hwtracing/coresight/coresight-trbe.c >> @@ -1494,9 +1494,9 @@ static int arm_trbe_device_probe(struct platform_device *pdev) >> if (!drvdata) >> return -ENOMEM; >> - pdata = coresight_get_platform_data(dev); >> - if (IS_ERR(pdata)) >> - return PTR_ERR(pdata); >> + pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); >> + if (!pdata) >> + return -ENOMEM; > > Please could you add a comment in here, on why we use a dummy platform > data ? It is good to have documented it in the code too. Sure, will add the following in-code documentation. + /* + * TRBE coresight devices do not need regular connections + * information, as the paths get built between all percpu + * source and their respective percpu sink devices. Though + * coresight_register() expect device connections via the + * platform_data, which TRBE devices do not have. As they + * are not real ACPI devices, coresight_get_platform_dat() + * ends up failing. Instead let's allocate a dummy zeroed + * coresight_platform_data structure and assign that back + * into the device for that purpose. + */
On 04/08/2023 10:18, Anshuman Khandual wrote: > > > On 8/3/23 19:25, Suzuki K Poulose wrote: >> On 03/08/2023 06:56, Anshuman Khandual wrote: >>> TRBE coresight devices do not need regular connections information, as the >>> paths get built between all percpu source and their respective percpu sink >>> devices. Please refer 'commit 2cd87a7b293d ("coresight: core: Add support >>> for dedicated percpu sinks")' which added support for percpu sink devices. >>> >>> coresight_register() expect device connections via the platform_data. TRBE >>> devices do not have any graph connections and thus is empty. With upcoming >>> ACPI support for TRBE, we do not get a real acpi_device and thus >>> coresight_get_platform_dat() will end up in failures. Hence this allocates >>> a zeroed coresight_platform_data structure and assigns that back into the >>> device. >>> >>> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> >>> Cc: Mike Leach <mike.leach@linaro.org> >>> Cc: Leo Yan <leo.yan@linaro.org> >>> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> >>> Cc: coresight@lists.linaro.org >>> Cc: linux-arm-kernel@lists.infradead.org >>> Cc: linux-kernel@vger.kernel.org >>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >>> --- >>> drivers/hwtracing/coresight/coresight-trbe.c | 6 +++--- >>> 1 file changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c >>> index 7720619909d6..e1d9d06e7725 100644 >>> --- a/drivers/hwtracing/coresight/coresight-trbe.c >>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c >>> @@ -1494,9 +1494,9 @@ static int arm_trbe_device_probe(struct platform_device *pdev) >>> if (!drvdata) >>> return -ENOMEM; >>> - pdata = coresight_get_platform_data(dev); >>> - if (IS_ERR(pdata)) >>> - return PTR_ERR(pdata); >>> + pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); >>> + if (!pdata) >>> + return -ENOMEM; >> >> Please could you add a comment in here, on why we use a dummy platform >> data ? It is good to have documented it in the code too. > > Sure, will add the following in-code documentation. > > + /* > + * TRBE coresight devices do not need regular connections > + * information, as the paths get built between all percpu > + * source and their respective percpu sink devices. Though > + * coresight_register() expect device connections via the > + * platform_data, which TRBE devices do not have. As they > + * are not real ACPI devices, coresight_get_platform_dat() minor nit: s/coresight_get_platform_dat/coresight_get_platform_data/ here and above in the description. Otherwise, looks good. Suzuki
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c index 7720619909d6..e1d9d06e7725 100644 --- a/drivers/hwtracing/coresight/coresight-trbe.c +++ b/drivers/hwtracing/coresight/coresight-trbe.c @@ -1494,9 +1494,9 @@ static int arm_trbe_device_probe(struct platform_device *pdev) if (!drvdata) return -ENOMEM; - pdata = coresight_get_platform_data(dev); - if (IS_ERR(pdata)) - return PTR_ERR(pdata); + pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); + if (!pdata) + return -ENOMEM; dev_set_drvdata(dev, drvdata); dev->platform_data = pdata;
TRBE coresight devices do not need regular connections information, as the paths get built between all percpu source and their respective percpu sink devices. Please refer 'commit 2cd87a7b293d ("coresight: core: Add support for dedicated percpu sinks")' which added support for percpu sink devices. coresight_register() expect device connections via the platform_data. TRBE devices do not have any graph connections and thus is empty. With upcoming ACPI support for TRBE, we do not get a real acpi_device and thus coresight_get_platform_dat() will end up in failures. Hence this allocates a zeroed coresight_platform_data structure and assigns that back into the device. Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Mike Leach <mike.leach@linaro.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- drivers/hwtracing/coresight/coresight-trbe.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)