RE: [PATCH V8 2/9] drivers core: add ACPI based WBRF mechanism introduced by AMD

Quan, Evan
2023-08-14T07:46:56Z

[AMD Official Use Only - General]

> -----Original Message-----
> From: Simon Horman <horms@kernel.org>
> Sent: Friday, August 11, 2023 5:38 PM
> To: Quan, Evan <Evan.Quan@amd.com>
> Cc: rafael@kernel.org; lenb@kernel.org; Deucher, Alexander
> <Alexander.Deucher@amd.com>; Koenig, Christian
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> Subject: Re: [PATCH V8 2/9] drivers core: add ACPI based WBRF mechanism
> introduced by AMD
>
> On Thu, Aug 10, 2023 at 03:37:56PM +0800, Evan Quan wrote:
> > AMD has introduced an ACPI based mechanism to support WBRF for some
> > platforms with AMD dGPU + WLAN. This needs support from BIOS equipped
> > with necessary AML implementations and dGPU firmwares.
> >
> > For those systems without the ACPI mechanism and developing solutions,
> > user can use/fall-back the generic WBRF solution for diagnosing potential
> > interference issues.
> >
> > And for the platform which does not equip with the necessary AMD ACPI
> > implementations but with CONFIG_WBRF_AMD_ACPI built as 'y', it will
> > fall back to generic WBRF solution if the `wbrf` is set as "on".
> >
> > Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
> > Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> > Co-developed-by: Evan Quan <evan.quan@amd.com>
> > Signed-off-by: Evan Quan <evan.quan@amd.com>
>
> ...
>
> > diff --git a/drivers/acpi/amd_wbrf.c b/drivers/acpi/amd_wbrf.c
>
> ...
>
> > +static bool check_acpi_wbrf(acpi_handle handle, u64 rev, u64 funcs)
> > +{
> > + int i;
> > + u64 mask = 0;
> > + union acpi_object *obj;
> > +
> > + if (funcs == 0)
> > + return false;
> > +
> > + obj = acpi_evaluate_wbrf(handle, rev, 0);
> > + if (!obj)
> > + return false;
> > +
> > + if (obj->type != ACPI_TYPE_BUFFER)
> > + return false;
> > +
> > + /*
> > + * Bit vector providing supported functions information.
> > + * Each bit marks support for one specific function of the WBRF
> method.
> > + */
> > + for (i = 0; i < obj->buffer.length && i < 8; i++)
> > + mask |= (((u64)obj->buffer.pointer[i]) << (i * 8));
> > +
> > + ACPI_FREE(obj);
> > +
> > + if ((mask & BIT(WBRF_ENABLED)) &&
> > + (mask & funcs) == funcs)
>
> Hi Evan,
>
> a minor nit from my side: the indentation of the line above seems odd.
Thanks. Will update this.

Evan
>
> if ((mask & BIT(WBRF_ENABLED)) &&
> (mask & funcs) == funcs)
>
> > + return true;
> > +
> > + return false;
> > +}
>
> ...