Qualcomm Camera Subsystem

Qualcomm SoCs contain a block called CAMSS (camera subsystem). For more information about some of the components that are part of it see Qualcomm Camera Subsystem driver - The Linux Kernel documentation.

This page only contains some more detailed information about the Qualcomm Camera Subsystem, for the general overview please view Camera#Qualcomm.

Test pattern

The CSID part of CAMSS can produce a pattern useful for testing CAMSS without any data from the sensor (which would normally provide the data).

$ v4l2-ctl -d /dev/v4l-subdev3 -L

Image Processing Controls

                   test_pattern 0x009f0903 (menu)   : min=0 max=6 default=0 value=0 (Disabled)
                                0: Disabled
                                1: Incrementing
                                2: Alternating 0x55/0xAA
                                3: All Zeros 0x00
                                4: All Ones 0xFF
                                5: Pseudo-random Data
                                6: User Specified

Newer SoCs additionally have the patterns "Complex pattern", "Color box" and "Color bars".

You can enable the test pattern using e.g. v4l2-ctl -d /dev/v4l-subdev3 -c test_pattern=2 to enable "Alternating 0x55/0xAA". Set to to 0/"Disabled" again to take the data from the sensor.

Also note, that most sensors also provide test patterns that can be used to test the pipeline from sensor to final picture, so CSID test pattern isn't the only test pattern available in V4L2.

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  Pattern 1

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  Pattern 2

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  Pattern 3

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  Pattern 4

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  Pattern 5