ipa: ipu3: Rework IPAFrameContext

Currently, IPAFrameContext consolidates the values computed by the
active state of the algorithms, along with the values applied on
the sensor.

Moving ahead, we want to have a frame context associated with each
incoming request (or frame to be captured). This shouldn't necessarily
be tied to "active state" of the algorithms hence:

- Rename current IPAFrameContext -> IPAActiveState
  This will now reflect the latest active state of the algorithms and
  has nothing to do with any frame-related ops/values.

- Re-instate IPAFrameContext with a sub-structure 'sensor' currently
  storing the exposure and gain value.

Adapt the various access to the frame context to the new changes
as described above.

Subsequently, the re-instated IPAFrameContext will be extended to
contain a frame number and ControlList to remember the incoming
request controls provided by the application. A ring-buffer will
be introduced to store these frame contexts for a certain number
of frames.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 50 insertions, 38 deletions

diff --git a/src/ipa/ipu3/ipa_context.cpp b/src/ipa/ipu3/ipa_context.cpp
index b1570dde..383c2e37 100644
--- a/src/ipa/ipu3/ipa_context.cpp
+++ b/src/ipa/ipu3/ipa_context.cpp
@@ -25,18 +25,30 @@ namespace libcamera::ipa::ipu3 {
  */
 
 /**
+ * \struct IPAActiveState
+ * \brief The active state of the IPA algorithms
+ *
+ * The IPA is fed with the statistics generated from the latest frame captured
+ * by the hardware. The statistics are then processed by the IPA algorithms to
+ * compute ISP parameters required for the next frame capture. The current state
+ * of the algorithms is reflected through the IPAActiveState to store the values
+ * most recently computed by the IPA algorithms.
+ */
+
+/**
  * \struct IPAFrameContext
- * \brief Per-frame context for algorithms
+ * \brief Context for a frame
  *
  * The frame context stores data specific to a single frame processed by the
  * IPA. Each frame processed by the IPA has a context associated with it,
  * accessible through the IPAContext structure.
  *
- * \todo Detail how to access contexts for a particular frame
- *
- * Each of the fields in the frame context belongs to either a specific
- * algorithm, or to the top-level IPA module. A field may be read by any
- * algorithm, but should only be written by its owner.
+ * Fields in the frame context should reflect values and controls
+ * associated with the specific frame as requested by the application, and
+ * as configured by the hardware. Fields can be read by algorithms to
+ * determine if they should update any specific action for this frame, and
+ * finally to update the metadata control lists when the frame is fully
+ * completed.
  */
 
 /**
@@ -49,10 +61,10 @@ namespace libcamera::ipa::ipu3 {
  * \var IPAContext::frameContext
  * \brief The frame context for the frame being processed
  *
- * \todo While the frame context is supposed to be per-frame, this
- * single frame context stores data related to both the current frame
- * and the previous frames, with fields being updated as the algorithms
- * are run. This needs to be turned into real per-frame data storage.
+ * \var IPAContext::activeState
+ * \brief The current state of IPA algorithms
+ *
+ * \todo The frame context needs to be turned into real per-frame data storage.
  */
 
 /**
@@ -78,17 +90,17 @@ namespace libcamera::ipa::ipu3 {
  */
 
 /**
- * \var IPAFrameContext::af
+ * \var IPAActiveState::af
  * \brief Context for the Automatic Focus algorithm
  *
- * \struct  IPAFrameContext::af
- * \var IPAFrameContext::af.focus
+ * \struct IPAActiveState::af
+ * \var IPAActiveState::af.focus
  * \brief Current position of the lens
  *
- * \var IPAFrameContext::af.maxVariance
+ * \var IPAActiveState::af.maxVariance
  * \brief The maximum variance of the current image.
  *
- * \var IPAFrameContext::af.stable
+ * \var IPAActiveState::af.stable
  * \brief It is set to true, if the best focus is found.
  */
 
@@ -121,64 +133,64 @@ namespace libcamera::ipa::ipu3 {
  */
 
 /**
- * \var IPAFrameContext::agc
+ * \var IPAActiveState::agc
  * \brief Context for the Automatic Gain Control algorithm
  *
  * The exposure and gain determined are expected to be applied to the sensor
  * at the earliest opportunity.
  *
- * \var IPAFrameContext::agc.exposure
+ * \var IPAActiveState::agc.exposure
  * \brief Exposure time expressed as a number of lines
  *
- * \var IPAFrameContext::agc.gain
+ * \var IPAActiveState::agc.gain
  * \brief Analogue gain multiplier
  *
  * The gain should be adapted to the sensor specific gain code before applying.
  */
 
 /**
- * \var IPAFrameContext::awb
+ * \var IPAActiveState::awb
  * \brief Context for the Automatic White Balance algorithm
  *
- * \struct IPAFrameContext::awb.gains
+ * \struct IPAActiveState::awb.gains
  * \brief White balance gains
  *
- * \var IPAFrameContext::awb.gains.red
+ * \var IPAActiveState::awb.gains.red
  * \brief White balance gain for R channel
  *
- * \var IPAFrameContext::awb.gains.green
+ * \var IPAActiveState::awb.gains.green
  * \brief White balance gain for G channel
  *
- * \var IPAFrameContext::awb.gains.blue
+ * \var IPAActiveState::awb.gains.blue
  * \brief White balance gain for B channel
  *
- * \var IPAFrameContext::awb.temperatureK
+ * \var IPAActiveState::awb.temperatureK
  * \brief Estimated color temperature
  */
 
 /**
- * \var IPAFrameContext::sensor
- * \brief Effective sensor values
- *
- * \var IPAFrameContext::sensor.exposure
- * \brief Exposure time expressed as a number of lines
- *
- * \var IPAFrameContext::sensor.gain
- * \brief Analogue gain multiplier
- */
-
-/**
- * \var IPAFrameContext::toneMapping
+ * \var IPAActiveState::toneMapping
  * \brief Context for ToneMapping and Gamma control
  *
- * \var IPAFrameContext::toneMapping.gamma
+ * \var IPAActiveState::toneMapping.gamma
  * \brief Gamma value for the LUT
  *
- * \var IPAFrameContext::toneMapping.gammaCorrection
+ * \var IPAActiveState::toneMapping.gammaCorrection
  * \brief Per-pixel tone mapping implemented as a LUT
  *
  * The LUT structure is defined by the IPU3 kernel interface. See
  * <linux/intel-ipu3.h> struct ipu3_uapi_gamma_corr_lut for further details.
  */
 
+/**
+ * \var IPAFrameContext::sensor
+ * \brief Effective sensor values that were applied for the frame
+ *
+ * \var IPAFrameContext::sensor.exposure
+ * \brief Exposure time expressed as a number of lines
+ *
+ * \var IPAFrameContext::sensor.gain
+ * \brief Analogue gain multiplier
+ */
+
 } /* namespace libcamera::ipa::ipu3 */