[Nouveau] [PATCH 5/8] acpi: Check returned object type by Optimus _DSM locally

[Ilia Mirkin]

On Tue, May 26, 2015 at 1:10 AM, Pierre Moreau <pierre.morrow at free.fr> wrote:
>> On 26 May 2015, at 00:39, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>
>>> On Mon, May 25, 2015 at 6:22 PM, Pierre Moreau <pierre.morrow at free.fr> wrote:
>>> Most _DSM will return an integer value of 0x80000002 when given an unknown
>>> UUID, revision ID or function ID. Checking locally allows us to differentiate
>>> that case from other ACPI errors, and to not report a "failed to evaluate _DSM"
>>> if 0x80000002 is returned which was confusing.
>>>
>>> Signed-off-by: Pierre Moreau <pierre.morrow at free.fr>
>>> ---
>>> drm/nouveau/nouveau_acpi.c | 15 ++++++++++++---
>>> 1 file changed, 12 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drm/nouveau/nouveau_acpi.c b/drm/nouveau/nouveau_acpi.c
>>> index 073f7d7..7aeaf7d 100644
>>> --- a/drm/nouveau/nouveau_acpi.c
>>> +++ b/drm/nouveau/nouveau_acpi.c
>>> @@ -88,12 +88,12 @@ static int nouveau_evaluate_optimus_dsm(acpi_handle handle, int func, int arg, u
>>>        for (i = 0; i < 4; i++)
>>>                args_buff[i] = (arg >> i * 8) & 0xFF;
>>>
>>> -       obj = acpi_evaluate_dsm_typed(handle, nouveau_op_dsm_muid, nouveau_op_dsm_rid,
>>> -                                     func, &argv4, ACPI_TYPE_BUFFER);
>>> +       obj = acpi_evaluate_dsm(handle, nouveau_op_dsm_muid, nouveau_op_dsm_rid,
>>> +                               func, &argv4);
>>>        if (!obj) {
>>>                acpi_handle_info(handle, "failed to evaluate _DSM\n");
>>>                return AE_ERROR;
>>> -       } else {
>>> +       } else if (obj->type == ACPI_TYPE_BUFFER) {
>>>                if (!result && obj->buffer.length == 4) {
>>>                        *result  = obj->buffer.pointer[0];
>>>                        *result |= (obj->buffer.pointer[1] << 8);
>>> @@ -101,6 +101,15 @@ static int nouveau_evaluate_optimus_dsm(acpi_handle handle, int func, int arg, u
>>>                        *result |= (obj->buffer.pointer[3] << 24);
>>>                }
>>>                ACPI_FREE(obj);
>>> +       } else if (obj->type == ACPI_TYPE_INTEGER &&
>>> +                  obj->integer.value == 0x80000002) {
>>> +               acpi_handle_debug(handle, "failed to query Optimus _DSM\n");
>>> +               ACPI_FREE(obj);
>>> +               return -ENODEV;
>>
>> should this be AE_ERROR?
>
> I would say no, because ACPI was parsed correctly, just that we didn't it give the correct arguments, or rather, the _DSM we tested isn't an Optimus one, but it could a mux or gmux. And I used ENODEV as it is the value returned by nouveau_evaluate_mux_dsm in the same context.

Hm ok. It just seemed odd to be returning AE_* in one context, and
-ENODEV in another context -- they're different types of errors.
However if the caller handles it, I guess it's OK... I haven't looked
at the API in depth.

>
>>
>>> +       } else {
>>> +               acpi_handle_err(handle, "unexpected returned value by Optimus _DSM\n");
>>> +               ACPI_FREE(obj);
>>> +               return AE_ERROR;
>>>        }
>>>
>>>        return 0;
>>> --
>>> 2.4.1
>>>
>>> _______________________________________________
>>> Nouveau mailing list
>>> Nouveau at lists.freedesktop.org
>>> http://lists.freedesktop.org/mailman/listinfo/nouveau