From 94b8395755cca629d9f8fc66912cd56e13f35bf6 Mon Sep 17 00:00:00 2001 From: Rodrigo Vivi Date: Mon, 8 Dec 2014 06:46:31 -0800 Subject: [PATCH] drm/i915: Introduce FBC DocBook. No functional changes. v2 (Paulo): Rebase. v3: Accept Daniel's suggestions: * remove unclear and duplicated explanation. * remove marketing like doc and replace by a simple one. * remove bdw_fbc_sw_flush documentation. Signed-off-by: Rodrigo Vivi Signed-off-by: Paulo Zanoni Signed-off-by: Daniel Vetter --- Documentation/DocBook/drm.tmpl | 5 +++++ drivers/gpu/drm/i915/intel_fbc.c | 44 ++++++++++++++++++++++++++++++++-------- 2 files changed, 40 insertions(+), 9 deletions(-) diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl index 56e2a9b65c68..4fc5d730959b 100644 --- a/Documentation/DocBook/drm.tmpl +++ b/Documentation/DocBook/drm.tmpl @@ -3926,6 +3926,11 @@ int num_ioctls; !Idrivers/gpu/drm/i915/intel_psr.c + Frame Buffer Compression (FBC) +!Pdrivers/gpu/drm/i915/intel_fbc.c Frame Buffer Compression (FBC) +!Idrivers/gpu/drm/i915/intel_fbc.c + + DPIO !Pdrivers/gpu/drm/i915/i915_reg.h DPIO diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c index f1eeb86a3d1b..4daceaeeb30d 100644 --- a/drivers/gpu/drm/i915/intel_fbc.c +++ b/drivers/gpu/drm/i915/intel_fbc.c @@ -21,20 +21,26 @@ * DEALINGS IN THE SOFTWARE. */ -#include "intel_drv.h" -#include "i915_drv.h" - -/* FBC, or Frame Buffer Compression, is a technique employed to compress the - * framebuffer contents in-memory, aiming at reducing the required bandwidth - * during in-memory transfers and, therefore, reduce the power packet. +/** + * DOC: Frame Buffer Compression (FBC) + * + * FBC tries to save memory bandwidth (and so power consumption) by + * compressing the amount of memory used by the display. It is total + * transparent to user space and completely handled in the kernel. * * The benefits of FBC are mostly visible with solid backgrounds and - * variation-less patterns. + * variation-less patterns. It comes from keeping the memory footprint small + * and having fewer memory pages opened and accessed for refreshing the display. * - * FBC-related functionality can be enabled by the means of the - * i915.i915_fbc_enable parameter + * i915 is responsible to reserve stolen memory for FBC and configure its + * offset on proper registers. The hardware takes care of all + * compress/decompress. However there are many known cases where we have to + * forcibly disable it to allow proper screen updates. */ +#include "intel_drv.h" +#include "i915_drv.h" + static void i8xx_fbc_disable(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; @@ -318,6 +324,14 @@ static void gen7_fbc_enable(struct drm_crtc *crtc) DRM_DEBUG_KMS("enabled fbc on plane %c\n", plane_name(intel_crtc->plane)); } +/** + * intel_fbc_enabled - Is FBC enabled? + * @dev: the drm_device + * + * This function is used to verify the current state of FBC. + * FIXME: This should be tracked in the plane config eventually + * instead of queried at runtime for most callers. + */ bool intel_fbc_enabled(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; @@ -429,6 +443,12 @@ static void intel_fbc_enable(struct drm_crtc *crtc) schedule_delayed_work(&work->work, msecs_to_jiffies(50)); } +/** + * intel_fbc_disable - disable FBC + * @dev: the drm_device + * + * This function disables FBC. + */ void intel_fbc_disable(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; @@ -643,6 +663,12 @@ out_disable: i915_gem_stolen_cleanup_compression(dev); } +/** + * intel_fbc_init - Initialize FBC + * @dev_priv: the i915 device + * + * This function might be called during PM init process. + */ void intel_fbc_init(struct drm_i915_private *dev_priv) { if (!HAS_FBC(dev_priv)) { -- 2.11.0