[Intel-gfx] [PATCH 03/15] drm/i915: Add PSR docbook

[R, Durgadoss]

>-----Original Message-----
>From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of Rodrigo Vivi
>Sent: Friday, November 14, 2014 10:22 PM
>To: intel-gfx at lists.freedesktop.org
>Cc: Daniel Vetter; Vivi, Rodrigo
>Subject: [Intel-gfx] [PATCH 03/15] drm/i915: Add PSR docbook
>
>Let's document PSR a bit. No functional changes.
>
>v2: Add actual DocBook entry and accept Daniel's improvements.
>
>Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>---
> Documentation/DocBook/drm.tmpl   |  5 +++
> drivers/gpu/drm/i915/intel_psr.c | 73 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 78 insertions(+)
>
>diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
>index 9449cd6..a1168a8 100644
>--- a/Documentation/DocBook/drm.tmpl
>+++ b/Documentation/DocBook/drm.tmpl
>@@ -3893,6 +3893,11 @@ int num_ioctls;</synopsis>
> !Idrivers/gpu/drm/i915/intel_audio.c
>       </sect2>
>       <sect2>
>+	<title>Panel Self Refresh PSR (PSR/SRD)</title>
>+!Pdrivers/gpu/drm/i915/intel_psr.c Panel Self Refresh (PSR/SRD)
>+!Idrivers/gpu/drm/i915/intel_psr.c
>+      </sect2>
>+      <sect2>
>         <title>DPIO</title>
> !Pdrivers/gpu/drm/i915/i915_reg.h DPIO
> 	<table id="dpiox2">
>diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
>index 7b3ed91..716b8a9 100644
>--- a/drivers/gpu/drm/i915/intel_psr.c
>+++ b/drivers/gpu/drm/i915/intel_psr.c
>@@ -21,6 +21,36 @@
>  * DEALINGS IN THE SOFTWARE.
>  */
>
>+/**
>+ * DOC: Panel Self Refresh (PSR/SRD)
>+ *
>+ * Since Haswell Display controller supports Panel Self-Refresh on display
>+ * panels witch have a remote frame buffer (RFB) implemented according to PSR

s/witch/which ;)

oh, I see that this is already merged, anyway..

Thanks,
Durga

>+ * spec in eDP1.3. PSR feature allows the display to go to lower standby states
>+ * when system is idle but display is on as it eliminates display refresh
>+ * request to DDR memory completely as long as the frame buffer for that
>+ * display is unchanged.
>+ *
>+ * Panel Self Refresh must be supported by both Hardware (source) and
>+ * Panel (sink).
>+ *
>+ * PSR saves power by caching the framebuffer in the panel RFB, which allows us
>+ * to power down the link and memory controller. For DSI panels the same idea
>+ * is called "manual mode".
>+ *
>+ * The implementation uses the hardware-based PSR support which automatically
>+ * enters/exits self-refresh mode. The hardware takes care of sending the
>+ * required DP aux message and could even retrain the link (that part isn't
>+ * enabled yet though). The hardware also keeps track of any frontbuffer
>+ * changes to know when to exit self-refresh mode again. Unfortunately that
>+ * part doesn't work too well, hence why the i915 PSR support uses the
>+ * software frontbuffer tracking to make sure it doesn't miss a screen
>+ * update. For this integration intel_psr_invalidate() and intel_psr_flush()
>+ * get called by the frontbuffer tracking code. Note that because of locking
>+ * issues the self-refresh re-enable code is done from a work queue, which
>+ * must be correctly synchronized/cancelled when shutting down the pipe."
>+ */
>+
> #include <drm/drmP.h>
>
> #include "intel_drv.h"
>@@ -217,6 +247,12 @@ static void intel_psr_do_enable(struct intel_dp *intel_dp)
> 	dev_priv->psr.active = true;
> }
>
>+/**
>+ * intel_psr_enable - Enable PSR
>+ * @intel_dp: Intel DP
>+ *
>+ * This function can only be called after the pipe is fully trained and enabled.
>+ */
> void intel_psr_enable(struct intel_dp *intel_dp)
> {
> 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
>@@ -258,6 +294,12 @@ unlock:
> 	mutex_unlock(&dev_priv->psr.lock);
> }
>
>+/**
>+ * intel_psr_disable - Disable PSR
>+ * @intel_dp: Intel DP
>+ *
>+ * This function needs to be called before disabling pipe.
>+ */
> void intel_psr_disable(struct intel_dp *intel_dp)
> {
> 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
>@@ -342,6 +384,18 @@ static void intel_psr_exit(struct drm_device *dev)
>
> }
>
>+/**
>+ * intel_psr_invalidate - Invalidade PSR
>+ * @dev: DRM device
>+ * @frontbuffer_bits: frontbuffer plane tracking bits
>+ *
>+ * Since the hardware frontbuffer tracking has gaps we need to integrate
>+ * with the software frontbuffer tracking. This function gets called every
>+ * time frontbuffer rendering starts and a buffer gets dirtied. PSR must be
>+ * disabled if the frontbuffer mask contains a buffer relevant to PSR.
>+ *
>+ * Dirty frontbuffers relevant to PSR are tracked in busy_frontbuffer_bits."
>+ */
> void intel_psr_invalidate(struct drm_device *dev,
> 			      unsigned frontbuffer_bits)
> {
>@@ -366,6 +420,18 @@ void intel_psr_invalidate(struct drm_device *dev,
> 	mutex_unlock(&dev_priv->psr.lock);
> }
>
>+/**
>+ * intel_psr_flush - Flush PSR
>+ * @dev: DRM device
>+ * @frontbuffer_bits: frontbuffer plane tracking bits
>+ *
>+ * Since the hardware frontbuffer tracking has gaps we need to integrate
>+ * with the software frontbuffer tracking. This function gets called every
>+ * time frontbuffer rendering has completed and flushed out to memory. PSR
>+ * can be enabled again if no other frontbuffer relevant to PSR is dirty.
>+ *
>+ * Dirty frontbuffers relevant to PSR are tracked in busy_frontbuffer_bits.
>+ */
> void intel_psr_flush(struct drm_device *dev,
> 			 unsigned frontbuffer_bits)
> {
>@@ -399,6 +465,13 @@ void intel_psr_flush(struct drm_device *dev,
> 	mutex_unlock(&dev_priv->psr.lock);
> }
>
>+/**
>+ * intel_psr_init - Init basic PSR work and mutex.
>+ * @dev: DRM device
>+ *
>+ * This function is  called only once at driver load to initialize basic
>+ * PSR stuff.
>+ */
> void intel_psr_init(struct drm_device *dev)
> {
> 	struct drm_i915_private *dev_priv = dev->dev_private;
>--
>1.9.3
>
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