Messages in this thread | | | Date | Fri, 4 Aug 2023 14:48:12 +0530 | Subject | Re: [PATCH V3 3/4] coresight: trbe: Add a representative coresight_platform_data for TRBE | From | Anshuman Khandual <> |
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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. + */
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