Allow handlers to declare their capabilities and allow clients to
obtain that information. So far we have these use cases:
* If the handler is able to switch DDC separately, clients need to
probe EDID with drm_get_edid_switcheroo(). We should allow them
to detect a capable handler to ensure this function only gets
called when needed.
* Likewise if the handler is unable to switch AUX separately, the active
client needs to communicate link training parameters to the inactive
client, which may then skip the AUX handshake and set up its output
with these pre-calibrated values (DisplayPort specification v1.1a,
section 2.5.3.3). Clients need a way to recognize such a situation.
The flags for the radeon_atpx_handler and amdgpu_atpx_handler are
initially set to 0, this can later on be amended with
handler_flags |= VGA_SWITCHEROO_CAN_SWITCH_DDC;
when a ->switch_ddc callback is added.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
Tested-by: Lukas Wunner <lukas@wunner.de>
[MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina 15"]
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/2b0d93ed6e511ca09e95e45e0b35627f330fabce.1452525860.git.lukas@wunner.de
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