Messages in this thread | | | Date | Fri, 4 Aug 2023 11:04:25 +0100 | Subject | Re: [PATCH V3 3/4] coresight: trbe: Add a representative coresight_platform_data for TRBE | From | Suzuki K Poulose <> |
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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
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