On Mon, 2022-06-06 at 13:15 +0000, Souza, Jose wrote:
> On Mon, 2022-06-06 at 11:16 +0300, Jani Nikula wrote:
> > On Mon, 06 Jun 2022, "Hogander, Jouni" <jouni.hogander@xxxxxxxxx>
> > wrote:
> > > On Fri, 2022-06-03 at 16:32 +0000, Souza, Jose wrote:
> > > > On Fri, 2022-06-03 at 13:14 +0000, Hogander, Jouni wrote:
> > > > > On Fri, 2022-06-03 at 15:43 +0300, Jani Nikula wrote:
> > > > > > On Fri, 03 Jun 2022, Jouni Högander <
> > > > > > jouni.hogander@xxxxxxxxx>
> > > > > > wrote:
> > > > > > > Export headless sku bit (bit 13) from opregion->header-
> > > > > > > >pcon as
> > > > > > > an
> > > > > > > interface to check if our device is headless
> > > > > > > configuration.
> > > > > > >
> > > > > > > Bspec: 53441
> > > > > > > Signed-off-by: Jouni Högander <jouni.hogander@xxxxxxxxx>
> > > > > > > ---
> > > > > > > drivers/gpu/drm/i915/display/intel_opregion.c | 12
> > > > > > > ++++++++++++
> > > > > > > drivers/gpu/drm/i915/display/intel_opregion.h | 7
> > > > > > > +++++++
> > > > > > > 2 files changed, 19 insertions(+)
> > > > > > >
> > > > > > > diff --git
> > > > > > > a/drivers/gpu/drm/i915/display/intel_opregion.c
> > > > > > > b/drivers/gpu/drm/i915/display/intel_opregion.c
> > > > > > > index f31e8c3f8ce0..eab3f2e6b786 100644
> > > > > > > --- a/drivers/gpu/drm/i915/display/intel_opregion.c
> > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_opregion.c
> > > > > > > @@ -53,6 +53,8 @@
> > > > > > > #define MBOX_ASLE_EXTBIT(4)/* Mailbox #5 */
> > > > > > > #define MBOX_BACKLIGHTBIT(5)/* Mailbox #2
> > > > > > > (valid from v3.x) */
> > > > > > >
> > > > > > > +#define PCON_HEADLESS_SKUBIT(13)
> > > > > >
> > > > > > Here we go again.
> > > > > >
> > > > > > What does headless mean here? The spec does not say. Does
> > > > > > it have
> > > > > > display hardware? Apparently yes, since otherwise we
> > > > > > wouldn't be
> > > > > > here.
> > > > >
> > > > > This is for hybrid setup with several display hw and the
> > > > > panel wont
> > > > > be
> > > > > connected into device driven by i915 driver.
> > > > >
> > > > > > We have INTEL_DISPLAY_ENABLED() which should do the right
> > > > > > thing
> > > > > > when
> > > > > > you
> > > > > > do have display hardware and have done output setup etc.
> > > > > > but want
> > > > > > to
> > > > > > force them disconnected, i.e. you take the hardware over
> > > > > > properly,
> > > > > > but
> > > > > > put it to sleep for power savings.
> > > > > >
> > > > > > Maybe we should bolt this opregion check in that macro?
> > > > > >
> > > > > > Maybe we need to use INTEL_DISPLAY_ENABLED() also to
> > > > > > prevent
> > > > > > polling.
> > > > >
> > > > > Thank you for pointing this out. HAS_DISPLAY I already notice
> > > > > and
> > > > > it's
> > > > > not suitable for what we want here. I think bolting this
> > > > > check into
> > > > > INTEL_DISPLAY_ENABLED as you suggested is enough. That will
> > > > > prevent
> > > > > waking up the hw into D0 state for polling.
> > > >
> > > > A headless sku should not have any DDI ports enabled, much
> > > > easier
> > > > check for that.
> > >
> > > Could you please clarify this a bit? What exactly you are
> > > thinking
> > > should be checked? Aren't DDI port also disabled when non-
> > > headless
> > > setup is in runtime suspend?
> >
> > I also think "headless" and "DDI ports enabled" need clarification.
> > They
> > are overloaded terms.
>
> In a properly setup headless sku, VBT should have all ports marked as
> disabled.
>
> intel_ddi_init() {
> ...
>
> if (!init_dp && !init_hdmi) {
> drm_dbg_kms(&dev_priv->drm,
> "VBT says port %c is not DVI/HDMI/DP compatible, respect it\n",
> port_name(port));
> return;
> }
>
>
> All DDI should return earlier in the above.
> So you can use the number of enabled connectors to know if it is a
> headless sku or not.
>
> So you can skip the pooling in case there is no connectors.
I went through this and to my understanding this polling doesn't happen
in setup where all ports are marked as disabled in VBT. Connector is
not initialized at all -> polling is not enabled when runtime suspend
happens.
BR,
Jouni Högander
