drm: Add helpers to kick off self refresh mode in drivers
This patch adds a new drm helper library to help drivers implement self refresh. Drivers choosing to use it will register crtcs and will receive callbacks when it's time to enter or exit self refresh mode. In its current form, it has a timer which will trigger after a driver-specified amount of inactivity. When the timer triggers, the helpers will submit a new atomic commit to shut the refreshing pipe off. On the next atomic commit, the drm core will revert the self refresh state and bring everything back up to be actively driven. From the driver's perspective, this works like a regular disable/enable cycle. The driver need only check the 'self_refresh_active' state in crtc_state. It should initiate self refresh mode on the panel and enter an off or low-power state. Changes in v2: - s/psr/self_refresh/ (Daniel) - integrated the psr exit into the commit that wakes it up (Jose/Daniel) - made the psr state per-crtc (Jose/Daniel) Changes in v3: - Remove the self_refresh_(active|changed) from connector state (Daniel) - Simplify loop in drm_self_refresh_helper_alter_state (Daniel) - Improve self_refresh_aware comment (Daniel) - s/self_refresh_state/self_refresh_data/ (Daniel) Changes in v4: - Move docbook location below panel (Daniel) - Improve docbook with references and more detailed explanation (Daniel) - Instead of register/unregister, use init/cleanup (Daniel) Changes in v5: - Resolved conflict in drm_atomic_helper.c #include block - Resolved conflict in rst with HDCP helper docs Changes in v6: - Fix include ordering, clean up forward declarations (Sam) Link to v1: https://patchwork.freedesktop.org/patch/msgid/20190228210939.83386-2-sean@poorly.run Link to v2: https://patchwork.freedesktop.org/patch/msgid/20190326204509.96515-1-sean@poorly.run Link to v3: https://patchwork.freedesktop.org/patch/msgid/20190502194956.218441-6-sean@poorly.run Link to v4: https://patchwork.freedesktop.org/patch/msgid/20190508160920.144739-6-sean@poorly.run Link to v5: https://patchwork.freedesktop.org/patch/msgid/20190611160844.257498-6-sean@poorly.run Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Jose Souza <jose.souza@intel.com> Cc: Zain Wang <wzz@rock-chips.com> Cc: Tomasz Figa <tfiga@chromium.org> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Sam Ravnborg <sam@ravnborg.org> Tested-by:Heiko Stuebner <heiko@sntech.de> Reviewed-by: