Re: [Patch v5 2/2] ACPI: processor: reduce CPUFREQ thermal reduction pctg for Tegra241

[Sumit Gupta]

On 09/11/23 13:20, Hanjun Guo wrote:
> External email: Use caution opening links or attachments
>
>
> On 2023/10/20 16:30, Sumit Gupta wrote:
> > > > Current implementation of processor_thermal performs software 
> > > > throttling
> > > > in fixed steps of "20%" which can be too coarse for some platforms.
> > > > We observed some performance gain after reducing the throttle
> > > > percentage.
> > > > Change the CPUFREQ thermal reduction percentage and maximum thermal
> > > > steps
> > > > to be configurable. Also, update the default values of both for Nvidia
> > > > Tegra241 (Grace) SoC. The thermal reduction percentage is reduced to
> > > > "5%"
> > > > and accordingly the maximum number of thermal steps are increased as
> > > > they
> > > > are derived from the reduction percentage.
> > > >
> > > > Signed-off-by: Srikar Srimath Tirumala <srikars@xxxxxxxxxx>
> > > > Co-developed-by: Sumit Gupta <sumitg@xxxxxxxxxx>
> > > > Signed-off-by: Sumit Gupta <sumitg@xxxxxxxxxx>
> > > > ---
> > > >   drivers/acpi/arm64/Makefile          |  1 +
> > > >   drivers/acpi/arm64/thermal_cpufreq.c | 20 ++++++++++++++++
> > > >   drivers/acpi/processor_thermal.c     | 35 
> > > > +++++++++++++++++++++++++---
> > > >   include/linux/acpi.h                 |  9 +++++++
> > > >   4 files changed, 62 insertions(+), 3 deletions(-)
> > > >   create mode 100644 drivers/acpi/arm64/thermal_cpufreq.c
> > > >
> > > > diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
> > > > index 143debc1ba4a..3f181d8156cc 100644
> > > > --- a/drivers/acpi/arm64/Makefile
> > > > +++ b/drivers/acpi/arm64/Makefile
> > > > @@ -5,3 +5,4 @@ obj-$(CONFIG_ACPI_GTDT)         += gtdt.o
> > > >   obj-$(CONFIG_ACPI_APMT)        += apmt.o
> > > >   obj-$(CONFIG_ARM_AMBA)         += amba.o
> > > >   obj-y                          += dma.o init.o
> > > > +obj-$(CONFIG_ACPI)             += thermal_cpufreq.o
> > > > diff --git a/drivers/acpi/arm64/thermal_cpufreq.c
> > > > b/drivers/acpi/arm64/thermal_cpufreq.c
> > > > new file mode 100644
> > > > index 000000000000..de834fb013e7
> > > > --- /dev/null
> > > > +++ b/drivers/acpi/arm64/thermal_cpufreq.c
> > > > @@ -0,0 +1,20 @@
> > > > +// SPDX-License-Identifier: GPL-2.0-only
> > > > +#include <linux/acpi.h>
> > > > +
> > > > +#ifdef CONFIG_HAVE_ARM_SMCCC_DISCOVERY
> > > > +#define SMCCC_SOC_ID_T241      0x036b0241
> > > > +
> > > > +int acpi_thermal_cpufreq_pctg(void)
> > > > +{
> > > > +       s32 soc_id = arm_smccc_get_soc_id_version();
> > > > +
> > > > +       /*
> > > > +        * Check JEP106 code for NVIDIA Tegra241 chip (036b:0241) and
> > > > +        * reduce the CPUFREQ Thermal reduction percentage to 5%.
> > > > +        */
> > > > +       if (soc_id == SMCCC_SOC_ID_T241)
> > > > +               return 5;
> > > > +
> > > > +       return 0;
> > > > +}
> > > > +#endif
> > >
> > > This part needs an ACK from the ARM folks.
> > Sorry, missed adding 'ACPI arm64' maintainers. Added Lorenzo, Sudeep and
> > Hanjun.
>
> Sorry for the late reply, would mind giving me the link which the ID
> (SMCCC_SOC_ID_T241) is documented?
>
> Thanks
> Hanjun

The ID is already used in file 'irq-gic-v3.c'. Please refer change [1].

[1] 
https://lore.kernel.org/linux-arm-kernel/20230319024314.3540573-2-sdonthineni@xxxxxxxxxx/

Best Regards,
Sumit Gupta