[RFC PATCH 00/18] Generic DRRS implementation across the encoders

Ramalingam C
2015-06-26T13:59:43Z

Display Refresh Rate Switching (DRRS) is a power conservation feature
which enables swtching between low and high refresh rates,
dynamically, based on the usage scenario to save power.

This feature is applicable for internal panels.

Indication that the panel supports DRRS is given by the panel EDID, which
would list multiple refresh rates for one resolution along with VBT fields
like drrs_min_vrefresh.

DRRS is of 2 types - static and seamless.
Static needs full modeset. Which can be used in docking and undocking
scenarios.
Seamless DRRS involves changing RR without any visual effect to the user
and can be used during normal system usage. This is done by programming
certain registers.

Support for static/seamless DRRS may be indicated in the VBT based on
inputs from the panel spec.

We have implemented two DRRS use case scenrios :
1. Idleness DRRS, 2. Media playback DRRS (Content's FPS based)

Idleness DRRS:-
The implementation is based on frontbuffer tracking implementation.
When there is a disturbance on the screen triggered by user activity or a
periodic system activity, DRRS is disabled (RR is changed to high RR).
When there is no movement on screen, after a timeout, a switch
to low RR is made.
For integration with frontbuffer tracking code,
intel_drrs_invalidate() and intel_drrs_flush() are called.

Media playback DRRS (Content's FPS based):
Based on the content's Frames Per Second, minimum required vrefresh
is called in userspace. If the panel supports the minimum required vrefresh
and if the DRRS is supported on the platform, userspace will make a modeset
request with same mode and FB but with different vrefresh.
Panel's vrefresh range will be exposed through connector's modelist and
connector property is created to expose the DRRS capability to the userspace.

In DRRS state machine Media plyabck DRRS holds the highest priority.
Idleness DRRS is disabled as soon as Media playback DRRS is requested.
Idleness DRRS is reenabled when the userspace indicates the exit of Media
playback DRRS by requesting for highest vrefresh supported.

NOTE:
1. DRM documentation will be made once the RFC is closed along with IGT.
2. Currently in RFC, platform support is developed only for VLV.
it will be extended to other platform once the design is approved.
3. Basic design of DSI DRRS and Content based DRRS is functionally tested on
Android(VLV & CHT).

Ramalingam C (18):
drm/i915: Removing the eDP specific DRRS implementation
drm/i915: Generic DRRS state Machine
drm/i915: Addition of the drrs_min_vrefresh in VBT
drm/i915: Implementation of Generic DSI DRRS
drm/i915: Adjusting the pclk for dual link and burst mode
drm/i915: VLV dsi drrs support
drm/i915: Generic eDP DRRS implementation
drm/i915: VLV eDP DRRS methods
drm/i915: Cloned mode check
drm/i915: Initializing DRRS for all connectors
drm/i915: Updating the crtc modes in DRRS transitions
drm/i915: Redesigning dp_set_m_n to receive divider values
drm/i915: MEDIA_RR support in general DRRS state machine
drm/i915: MEDIA_RR support in eDP DRRS module
drm/i915: MEDIA_RR support in DSI DRRS module
drm/i915: Filtering media playback DRRS requests
drm/i915: Addition of downclock mode to connector modelist
drm/i915: Connector property for DRRS capability

drivers/gpu/drm/i915/Makefile | 3 +
drivers/gpu/drm/i915/i915_debugfs.c | 110 -----
drivers/gpu/drm/i915/i915_drv.h | 91 +++-
drivers/gpu/drm/i915/i915_reg.h | 4 +
drivers/gpu/drm/i915/intel_bios.c | 3 +
drivers/gpu/drm/i915/intel_bios.h | 9 +-
drivers/gpu/drm/i915/intel_ddi.c | 2 -
drivers/gpu/drm/i915/intel_display.c | 57 ++-
drivers/gpu/drm/i915/intel_dp.c | 397 +---------------
drivers/gpu/drm/i915/intel_drrs.c | 728 ++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/intel_drrs.h | 38 ++
drivers/gpu/drm/i915/intel_drv.h | 45 +-
drivers/gpu/drm/i915/intel_dsi.c | 29 +-
drivers/gpu/drm/i915/intel_dsi.h | 3 +
drivers/gpu/drm/i915/intel_dsi_drrs.c | 415 +++++++++++++++++
drivers/gpu/drm/i915/intel_dsi_drrs.h | 66 +++
drivers/gpu/drm/i915/intel_dsi_pll.c | 303 +++++++++++--
drivers/gpu/drm/i915/intel_edp_drrs.c | 196 ++++++++
drivers/gpu/drm/i915/intel_edp_drrs.h | 29 ++
drivers/gpu/drm/i915/intel_frontbuffer.c | 4 +-
drivers/gpu/drm/i915/intel_modes.c | 28 ++
21 files changed, 1959 insertions(+), 601 deletions(-)
create mode 100644 drivers/gpu/drm/i915/intel_drrs.c
create mode 100644 drivers/gpu/drm/i915/intel_drrs.h
create mode 100644 drivers/gpu/drm/i915/intel_dsi_drrs.c
create mode 100644 drivers/gpu/drm/i915/intel_dsi_drrs.h
create mode 100644 drivers/gpu/drm/i915/intel_edp_drrs.c
create mode 100644 drivers/gpu/drm/i915/intel_edp_drrs.h