[PATCH v3 0/4] media: Enable the OV5693 front camera on IPU6 Surface devices

[Fernando Rimoli <fernandorimoli11@gmail.com>]

This enables the OV5693 front camera on Intel IPU6 Surface devices such as
the Microsoft Surface Pro 9. Four pieces are needed on a stock kernel:

  1/4  ov5693: add the "OVTI5693" ACPI HID so the i2c core binds the driver
       (these devices enumerate the sensor as OVTI5693, not INT33BE).
  2/4  ipu-bridge: add the same HID so the bridge builds the sensor's fwnode
       graph.
  3/4  ov5693: gate the MIPI clock lane when the endpoint requests a
       non-continuous clock, which the IPU6 CSI-2 receiver needs to lock.
  4/4  ipu-bridge: request the non-continuous clock for the ov5693, but only
       on IPU6 (matched against ipu6_pci_tbl).

v3 reworks the clock-lane gate per Sakari's review of v2: instead of writing
MIPI_CTRL00 unconditionally, the sensor now gates the clock lane only when
the "clock-noncontinuous" endpoint property is present (the
V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK flag), the same way ov5647 does, and the
ipu-bridge supplies that property, gated on the IPU6 PCI IDs. The property is
set only for the ov5693 HIDs and only when the bridge sits on a PCI device
matching ipu6_pci_tbl, so IPU3 users of the same sensor and the non-PCI IVSC
bridge path are left untouched. I scoped it to all ipu6_pci_tbl IDs since the
gate is confirmed needed across two IPU6 generations (see below), happy to
narrow it to specific IDs if you would prefer.

On the register value: unlike ov5647, patch 3 sets bit 5 (clock-lane gate)
and bit 2 (LP11 idle) but not bit 4 (line sync). I re-swept the register at
runtime on my Surface Pro 9 (IPU6) to check bit 4 specifically: 0x24
(bit5+bit2) streams 300/300 frames at ~28 fps, but adding bit 4 (i.e.
ov5647's 0x34) collapses the stream to a couple of frames, and bit 4 alone
fails outright. A bit5-only value recovered to 300/300 in the same run, so
this is a value effect. This matches your point that the IPU6 PHYs differ
(ov2740 writes this register to 0 on Thinkpad IPU6), the ov5693 on IPU6
wants exactly bit5+bit2. Register read-back confirmed the power-on default
is 0x00.

Patches 1-2 are independent and useful on their own for enumeration; patch 1
carries Dan Scally's Reviewed-by from v1.

Changes since v2 [1]:
- Reworked patch 3: gate the MIPI clock lane on the "clock-noncontinuous"
  endpoint property (V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK) rather than writing
  MIPI_CTRL00 unconditionally, following ov5647. When the flag is absent the
  register is left at its reset default (IPU3 and others unaffected).
- New patch 4: ipu-bridge sets "clock-noncontinuous" for the ov5693, gated on
  the IPU6 PCI IDs (ipu6_pci_tbl), skipping non-PCI bridge instances.
- Characterised bit 4 (line sync) on IPU6 and documented why the value stays
  bit5+bit2, differing from ov5647.
- Patch 3 was reworked but is functionally identical on tested hardware (the
  same register value is written whenever the bridge sets the property), so I
  kept Jakob Berg Jespersen's Tested-by; Jakob, please shout if you would
  rather re-test v3.

The two IPU6 units the gate has been tested on: Surface Pro 9 (IPU6EP_ADLP,
0x465d) and, via Jakob, Surface Pro 7+ (IPU6, Tiger Lake, 0x9a19).

[1] https://lore.kernel.org/linux-media/20260717132021.18034-1-fernandorimoli11@gmail.com/

Fernando Rimoli (4):
  media: i2c: ov5693: Add OVTI5693 ACPI HID
  media: ipu-bridge: Add OVTI5693 to the list of supported sensors
  media: i2c: ov5693: Gate the MIPI clock lane for non-continuous clock
  media: ipu-bridge: Request non-continuous clock for ov5693 on IPU6

 drivers/media/i2c/ov5693.c           | 28 ++++++++++++++++++++++++
 drivers/media/pci/intel/ipu-bridge.c | 32 ++++++++++++++++++++++++++++
 include/media/ipu-bridge.h           |  2 +-
 3 files changed, 61 insertions(+), 1 deletion(-)

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2.43.0