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() > > 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. > >> 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. 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 >>> >
