Hi, On Wed 04 Nov 20, 13:36, Helen Koike wrote: > Hi Paul, > > On 11/4/20 8:11 AM, Paul Kocialkowski wrote: > > Hi Helen, > > > > On Fri 30 Oct 20, 19:44, Helen Koike wrote: > >> Hi Paul, > >> > >> I have some comments through the series, I hope this helps. > > > > Thanks for your comments :) > > > >> On 10/23/20 2:45 PM, Paul Kocialkowski wrote: > >>> This series introduces support for MIPI CSI-2, with the A31 controller that is > >>> found on most SoCs (A31, V3s and probably V5) as well as the A83T-specific > >>> controller. While the former uses the same MIPI D-PHY that is already supported > >>> for DSI, the latter embeds its own D-PHY. > >>> > >>> In order to distinguish the use of the D-PHY between Rx mode (for MIPI CSI-2) > >>> and Tx mode (for MIPI DSI), a submode is introduced for D-PHY in the PHY API. > >>> This allows adding Rx support in the A31 D-PHY driver. > >>> > >>> A few changes and fixes are applied to the A31 CSI controller driver, in order > >>> to support the MIPI CSI-2 use-case. > >>> > >>> Follows is the V4L2 device topology representing the interactions between > >>> the MIPI CSI-2 sensor, the MIPI CSI-2 controller (which controls the D-PHY) > >>> and the CSI controller: > >>> - entity 1: sun6i-csi (1 pad, 1 link) > >>> type Node subtype V4L flags 0 > >>> device node name /dev/video0 > >>> pad0: Sink > >>> <- "sun6i-mipi-csi2":1 [ENABLED,IMMUTABLE] > >>> > >>> - entity 5: sun6i-mipi-csi2 (2 pads, 2 links) > >>> type V4L2 subdev subtype Unknown flags 0 > >>> pad0: Sink > >>> <- "ov5648 0-0036":0 [ENABLED,IMMUTABLE] > >>> pad1: Source > >>> -> "sun6i-csi":0 [ENABLED,IMMUTABLE] > >>> > >>> - entity 8: ov5648 0-0036 (1 pad, 1 link) > >>> type V4L2 subdev subtype Sensor flags 0 > >>> device node name /dev/v4l-subdev0 > >> > >> Question: I noticed is that sun6i-mipi-csi2 doesn't expose a node under /dev/, but the sensor > >> exposes it. Probably because it uses V4L2_SUBDEV_FL_HAS_DEVNODE and sun6i-csi() calls > >> v4l2_device_register_subdev_nodes(). > >> > >> I find this weird from a userspace pov, since usually we don't mix manual and auto propagation > >> of the configs, so I started wondering if sun6i-csi driver should be calling > >> v4l2_device_register_subdev_nodes() in the first place. > > > > I must admit that I didn't really pay attention to that, but since > > sun6i-mipi-csi2 is basically a bridge driver, it doesn't make sense to apply > > manual configuration to it. It is actually designed to forward most subdev ops > > to its own subdev so configuring it manually would actually result in > > configuring the sensor. > > Ack, then maybe sun6i-csi needs a patch removing the call to v4l2_device_register_subdev_nodes() Apparently Sakari suggested that we do need a subdev node for the MIPI CSI-2 bridge so I'll just do that. This implementation that fowards the ops to the sensor was apparently a mistake. Paul > > > > XXX > > > >> Also, sun6i-csi doesn't seem to be used by any board dts (it's declared on the dtsi, but I > >> didn't find any dts enabling it), so I wonder if it would be a bad thing if we update it. > >> > >>> pad0: Source > >>> [fmt:SBGGR8_1X8/640x480@1/30 field:none colorspace:raw xfer:none ycbcr:601 quantization:full-range] > >>> -> "sun6i-mipi-csi2":0 [ENABLED,IMMUTABLE] > >> > >> If I understand correctly, this is very similar to ipu3: > >> sensor->bus->dma_engine > >> > >> in the case of ipu3-cio2: > >> sensor->ipu3-csi2->ipu3-cio2 > >> > >> in this case: > >> ov5648->sun6i-mipi-csi2->sun6i-csi > > > > Yes this is the correct picture. > > > >> On thing that is confusing me is the name csi2 with csi (that makes me think of csi > >> version one, which is not the case), I would rename it to sun6i-video (or maybe > >> it is just me who gets confused). > > > > So the CSI name comes from the Allwinner litterature and implementation for that > > controller. Since it supports parallel input on its own, it does in fact support > > parallel CSI. The DMA engine part alone from that controller is also used for > > MIPI CSI-2, so in this case the name looses its relevance. > > > >> I know this driver is already upstream and not part of this series, but on the other hand it > >> doesn't seem to be used. > > > > Personally I don't find a rename to be necessary and while I agree that > > nothing would apparently prevent us from renaming it, I would prefer to keep > > the naming in line with Allwinner's litterature. > > Ok, I didn't know it was from Allwinner's litterature, I don't mind keeping the name. Great :) > >> On another note, I always wonder if we should expose the bus in the topology, I'm not > >> sure if it provides any useful API or information for userspace, and you could have > >> a cleaner code (maybe code could be under phy subsystem). But at the same time, it > >> seems this is a pattern on v4l2. > >> > >> I'd like to hear what others think on the above. > > > > My view on this is that we are dealing with two distinct controllers here, > > one that acts as a DMA engine and one that acts as a bridge. As a result, two > > chained subdevs looks like the most appropriate representation to me. > > > > Using the PHY subsystem would probably be abusing the framework since the > > MIPI CSI-2 controller is not a PHY (and we do have a D-PHY driver for the D-PHY > > part that uses the PHY API already). > > > > So tl;dr I don't agree that it would be cleaner. > > My point is, this is a "dummy" subdevice in userspace pov, > but if it is only used with auto-propagation of the configurations, then > it doesn't matter (since userspace won't interact with that node). > And in the kernel space you need to implement media boilerplate code. > So I was trying to think in another alternative, but tbh I don't mind > keeping it in the media topology. Undestood and thanks for sharing your thoughts either way, they are definitely welcome! Cheers, Paul > Regards, > Helen > > > > > Cheers, > > > > Paul > > > >>> Happy reviewing! > >>> > >>> Paul Kocialkowski (14): > >>> phy: Distinguish between Rx and Tx for MIPI D-PHY with submodes > >>> phy: allwinner: phy-sun6i-mipi-dphy: Support D-PHY Rx mode for MIPI > >>> CSI-2 > >>> media: sun6i-csi: Support an optional dedicated memory pool > >>> media: sun6i-csi: Fix the image storage bpp for 10/12-bit Bayer > >>> formats > >>> media: sun6i-csi: Only configure the interface data width for parallel > >>> media: sun6i-csi: Support feeding from the MIPI CSI-2 controller > >>> dt-bindings: media: i2c: Add A31 MIPI CSI-2 bindings documentation > >>> media: sunxi: Add support for the A31 MIPI CSI-2 controller > >>> ARM: dts: sun8i: v3s: Add CSI0 camera interface node > >>> ARM: dts: sun8i: v3s: Add MIPI D-PHY and MIPI CSI-2 interface nodes > >>> dt-bindings: media: i2c: Add A83T MIPI CSI-2 bindings documentation > >>> media: sunxi: Add support for the A83T MIPI CSI-2 controller > >>> ARM: dts: sun8i: a83t: Add MIPI CSI-2 controller node > >>> media: sunxi: sun8i-a83t-mipi-csi2: Avoid using the (unsolicited) > >>> interrupt > >>> > >>> .../media/allwinner,sun6i-a31-mipi-csi2.yaml | 168 +++++ > >>> .../media/allwinner,sun8i-a83t-mipi-csi2.yaml | 158 +++++ > >>> arch/arm/boot/dts/sun8i-a83t.dtsi | 26 + > >>> arch/arm/boot/dts/sun8i-v3s.dtsi | 62 ++ > >>> drivers/media/platform/sunxi/Kconfig | 2 + > >>> drivers/media/platform/sunxi/Makefile | 2 + > >>> .../platform/sunxi/sun6i-csi/sun6i_csi.c | 54 +- > >>> .../platform/sunxi/sun6i-csi/sun6i_csi.h | 20 +- > >>> .../platform/sunxi/sun6i-mipi-csi2/Kconfig | 11 + > >>> .../platform/sunxi/sun6i-mipi-csi2/Makefile | 4 + > >>> .../sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c | 635 +++++++++++++++++ > >>> .../sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.h | 116 +++ > >>> .../sunxi/sun8i-a83t-mipi-csi2/Kconfig | 11 + > >>> .../sunxi/sun8i-a83t-mipi-csi2/Makefile | 4 + > >>> .../sun8i-a83t-mipi-csi2/sun8i_a83t_dphy.c | 92 +++ > >>> .../sun8i-a83t-mipi-csi2/sun8i_a83t_dphy.h | 39 ++ > >>> .../sun8i_a83t_mipi_csi2.c | 660 ++++++++++++++++++ > >>> .../sun8i_a83t_mipi_csi2.h | 196 ++++++ > >>> drivers/phy/allwinner/phy-sun6i-mipi-dphy.c | 164 ++++- > >>> drivers/staging/media/rkisp1/rkisp1-isp.c | 3 +- > >>> include/linux/phy/phy-mipi-dphy.h | 13 + > >>> 21 files changed, 2408 insertions(+), 32 deletions(-) > >>> create mode 100644 Documentation/devicetree/bindings/media/allwinner,sun6i-a31-mipi-csi2.yaml > >>> create mode 100644 Documentation/devicetree/bindings/media/allwinner,sun8i-a83t-mipi-csi2.yaml > >>> create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/Kconfig > >>> create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/Makefile > >>> create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c > >>> create mode 100644 drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.h > >>> create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/Kconfig > >>> create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/Makefile > >>> create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_dphy.c > >>> create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_dphy.h > >>> create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c > >>> create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h > >>> > > -- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com
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