[libcamera-devel] [PATCH v2] libcamera: Add support for OmniVision OV8858

[Jacopo Mondi]

From: Nicholas Roth <nicholas at rothemail.net>

Support for the OmniVision OV8858 sensor is scheduled for inclusion in
the Linux kernel in version v6.3.

Add support for the sensor in libcamera by providing static properties
and a camera sensor helper in libipa.

The camera sensor helper expresses analogue gain increments in 1/128
step which differs from what is reported in the sensor documentation in
section "5.8 manual exposure compensation/ manual gain compensation" [0]

A more detailed analysis of the sensor gain model is reported at:
https://patchwork.linuxtv.org/project/linux-media/patch/20221106171129.166892-2-nicholas@rothemail.net/#142267

Record with a \todo note a reference to discussion on the gain model
implementation.

Signed-off-by: Nicholas Roth <nicholas at rothemail.net>
Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
---

Compared to initial Nicholas' submission:
- Change gain step to 128 (link to the driver discussion)
- Add fadeToGray test patter and adjust comment

---
 src/ipa/libipa/camera_sensor_helper.cpp    | 18 ++++++++++++++++++
 src/libcamera/camera_sensor_properties.cpp | 13 +++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp
index 3d8a2835fa28..52e11dfb8ca2 100644
--- a/src/ipa/libipa/camera_sensor_helper.cpp
+++ b/src/ipa/libipa/camera_sensor_helper.cpp
@@ -505,6 +505,24 @@ public:
 };
 REGISTER_CAMERA_SENSOR_HELPER("ov5693", CameraSensorHelperOv5693)

+class CameraSensorHelperOv8858 : public CameraSensorHelper
+{
+public:
+	CameraSensorHelperOv8858()
+	{
+		gainType_ = AnalogueGainLinear;
+
+		/*
+		 * \todo Use an increment step of 1/128 which differs from
+		 * what the sensor manual describes.
+		 *
+		 * See: https://patchwork.linuxtv.org/project/linux-media/patch/20221106171129.166892-2-nicholas@rothemail.net/#142267
+		 */
+		gainConstants_.linear = { 1, 0, 0, 128 };
+	}
+};
+REGISTER_CAMERA_SENSOR_HELPER("ov8858", CameraSensorHelperOv8858)
+
 class CameraSensorHelperOv8865 : public CameraSensorHelper
 {
 public:
diff --git a/src/libcamera/camera_sensor_properties.cpp b/src/libcamera/camera_sensor_properties.cpp
index c3c2caced906..7f6816e72773 100644
--- a/src/libcamera/camera_sensor_properties.cpp
+++ b/src/libcamera/camera_sensor_properties.cpp
@@ -167,6 +167,19 @@ const CameraSensorProperties *CameraSensorProperties::get(const std::string &sen
 				 */
 			},
 		} },
+		{ "ov8858", {
+			.unitCellSize = { 1120, 1120 },
+			.testPatternModes = {
+				{ controls::draft::TestPatternModeOff, 0 },
+				{ controls::draft::TestPatternModeColorBars, 1 },
+				{ controls::draft::TestPatternModeColorBarsFadeToGray, 2 },
+				/*
+				 * No corresponding test patter mode
+				 * 3: "Vertical Color Bar Type 3",
+				 * 4: "Vertical Color Bar Type 4"
+				 */
+			},
+		} },
 		{ "ov8865", {
 			.unitCellSize = { 1400, 1400 },
 			.testPatternModes = {
--
2.39.0