Re: [PATCH rtw-next v2] wifi: rtw89: acpi: check for _DSM function support before evaluating it

[Rosen Penev]

On Tue, Nov 3, 2026 at 4:47 PM Ping-Ke Shih <pkshih@xxxxxxxxxxx> wrote:
>
> Rosen Penev <rosenp@xxxxxxxxx> wrote:
> > When the WiFi device has no ACPI companion, or the firmware does not
> > implement a given rtw89 _DSM function, rtw89_acpi_evaluate_dsm() calls
> > acpi_evaluate_dsm() anyway. ACPI core then warns on every probe:
> >
> >   ACPI: \: failed to evaluate _DSM e8c3a8d2-694b-004f-82bd-fe8607803aa7 rev:0 func:10 (0x1001)
> >   ACPI: \: failed to evaluate _DSM e8c3a8d2-694b-004f-82bd-fe8607803aa7 rev:0 func:6 (0x1001)
> >
> > Here the handle is NULL, and acpi_evaluate_object() returns
> > AE_BAD_PARAMETER. All callers already treat failure as "no policy
> > provided by the platform", so this is only noise.
> >
> > Bail out early when there is no ACPI handle, as acpi_check_dsm() would
> > otherwise hit the same warning while querying function 0. Then use
> > acpi_check_dsm() so that functions the firmware does not advertise fail
> > quietly at debug level, as rtw89_acpi_evaluate_method() already does.
>
> Adding this check is fine to me. But my question in v1 is that
> acpi_check_dsm() checks func 0 to determine if BIT(func) is existing.
> Is it possible func 0 not existing, but BIT(func) existing?
Shouldn't happen, but who knows.  I can drop the acpi_check_dsm() part.

7bf2dfccc2dd70821104d15cbab7b6fca21872be

is effectively the same as this.

Note that this specific card was taken out of a laptop and placed in a
desktop, hence the warning.
>
> >
> > Seen on an RTL8852BE in a desktop PCIe slot.
> >
> > Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
> > ---
> >  v2: check handle separately. Remove Fixes.
> >  drivers/net/wireless/realtek/rtw89/acpi.c | 15 +++++++++++++--
> >  1 file changed, 13 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/wireless/realtek/rtw89/acpi.c b/drivers/net/wireless/realtek/rtw89/acpi.c
> > index ebb6cf555747..3396d42594b3 100644
> > --- a/drivers/net/wireless/realtek/rtw89/acpi.c
> > +++ b/drivers/net/wireless/realtek/rtw89/acpi.c
> > @@ -372,11 +372,22 @@ int rtw89_acpi_evaluate_dsm(struct rtw89_dev *rtwdev,
> >                             enum rtw89_acpi_dsm_func func,
> >                             struct rtw89_acpi_dsm_result *res)
> >  {
> > +       acpi_handle handle = ACPI_HANDLE(rtwdev->dev);
> >         union acpi_object *obj;
> >         int ret;
> >
> > -       obj = acpi_evaluate_dsm(ACPI_HANDLE(rtwdev->dev), &rtw89_guid,
> > -                               0, func, NULL);
> > +       if (!handle) {
> > +               rtw89_debug(rtwdev, RTW89_DBG_ACPI, "acpi dsm no handle\n");
> > +               return -ENODEV;
> > +       }
> > +
> > +       if (!acpi_check_dsm(handle, &rtw89_guid, 0, BIT(func))) {
> > +               rtw89_debug(rtwdev, RTW89_DBG_ACPI,
> > +                           "acpi dsm func %d not supported\n", func);
> > +               return -ENOENT;
> > +       }
> > +
> > +       obj = acpi_evaluate_dsm(handle, &rtw89_guid, 0, func, NULL);
> >         if (!obj) {
> >                 rtw89_debug(rtwdev, RTW89_DBG_ACPI,
> >                             "acpi dsm fail to evaluate func: %d\n", func);
> > --
> > 2.56.0
>