Re: [PATCH] drm/radeon: add new AMD ACPI header and update relevant code

[Luca Tettamanti <kronos.it@gmail.com>]

On Sat, Jul 28, 2012 at 05:29:25PM -0400, Alex Deucher wrote:
> On Sat, Jul 28, 2012 at 10:56 AM, Luca Tettamanti <kronos.it@gmail.com> wrote:
> > I just found the first problem (probably a BIOS bug):
> > ATIF_FUNCTION_GET_SYSTEM_PARAMETERS is implemented in the DSDT, but the
> > corresponding bit ATIF_GET_SYSTEM_PARAMETERS_SUPPORTED is not set :(
> > I intended to use the method to set up the notification handler but now
> > my BIOS says that it's not there even if it is...
> > Can I assume some default values (e.g. notifications are enabled and will
> > use 0x81 unless ATIF_FUNCTION_GET_SYSTEM_PARAMETERS says something
> > different)?
> 
> The spec says that the bits in the supported functions vector mean
> that if bit n is set, function n+1 exists, 

Hum, I don't follow. The vector in my case is 0x2 (1 << 1), that would
mean that ATIF_SELECT_ACTIVE_DISPLAYS_SUPPORTED (1 << 2) is supported?

Maybe if the bit n is set then functions 0..n are available? That would
(almost) match what I see...

> but it's possible that the
> spec is wrong and it's actually a 1 to 1 mapping; if bit n is set,
> function n is supported.  In which case the the supported functions
> vector bits should be:
> +/* supported functions vector */
> +#       define ATIF_GET_SYSTEM_PARAMETERS_SUPPORTED               (1 << 1)
> +#       define ATIF_GET_SYSTEM_BIOS_REQUESTS_SUPPORTED            (1 << 2)
> +#       define ATIF_SELECT_ACTIVE_DISPLAYS_SUPPORTED              (1 << 3)
> +#       define ATIF_GET_LID_STATE_SUPPORTED                       (1 << 4)
> +#       define ATIF_GET_TV_STANDARD_FROM_CMOS_SUPPORTED           (1 << 5)
> +#       define ATIF_SET_TV_STANDARD_IN_CMOS_SUPPORTED             (1 << 6)
> +#       define ATIF_GET_PANEL_EXPANSION_MODE_FROM_CMOS_SUPPORTED  (1 << 7)
> +#       define ATIF_SET_PANEL_EXPANSION_MODE_IN_CMOS_SUPPORTED    (1 << 8)
> +#       define ATIF_TEMPERATURE_CHANGE_NOTIFICATION_SUPPORTED     (1 << 13)
> +#       define ATIF_GET_GRAPHICS_DEVICE_TYPES_SUPPORTED           (1 << 15)
> 
> See if that lines up better. 

Not really... the value returned by VERIFY_INTERFACE is 0x2, but in the
DSDT I see:

ATIF_FUNCTION_GET_SYSTEM_PARAMETERS
ATIF_FUNCTION_GET_SYSTEM_BIOS_REQUESTS
ATIF_FUNCTION_GET_TV_STANDARD_FROM_CMOS
ATIF_FUNCTION_SET_TV_STANDARD_IN_CMOS

The implementation of the first one makes sense, the second is used for
brightness control. The other two _might_ be a leftover (the machine
does not have an analog TV out).

> I'm still new to these ACPI interfaces
> so I'm not an expert yet.

I've been exposed to a lot of ACPI code (I wrote the asus_atk0110
driver), in my experience the DSDT is full of crap: code copied&pasted
from other machines, leftover no longer used, and other stuff that's
plainly wrong.

Luca