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

[Quan, Evan]

[AMD Official Use Only - General]



> -----Original Message-----
> From: Simon Horman <horms at kernel.org>
> Sent: Friday, August 11, 2023 5:38 PM
> To: Quan, Evan <Evan.Quan at amd.com>
> Cc: rafael at kernel.org; lenb at kernel.org; Deucher, Alexander
> <Alexander.Deucher at 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 at amd.com>
> > Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
> > Co-developed-by: Evan Quan <evan.quan at amd.com>
> > Signed-off-by: Evan Quan <evan.quan at 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;
> > +}
> 
> ...