From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0F04C388F7 for ; Wed, 4 Nov 2020 11:11:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 81922223AB for ; Wed, 4 Nov 2020 11:11:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728523AbgKDLLp (ORCPT ); Wed, 4 Nov 2020 06:11:45 -0500 Received: from relay7-d.mail.gandi.net ([217.70.183.200]:56809 "EHLO relay7-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728287AbgKDLLp (ORCPT ); Wed, 4 Nov 2020 06:11:45 -0500 X-Originating-IP: 93.29.109.196 Received: from aptenodytes (196.109.29.93.rev.sfr.net [93.29.109.196]) (Authenticated sender: paul.kocialkowski@bootlin.com) by relay7-d.mail.gandi.net (Postfix) with ESMTPSA id 809622000D; Wed, 4 Nov 2020 11:11:37 +0000 (UTC) Date: Wed, 4 Nov 2020 12:11:37 +0100 From: Paul Kocialkowski To: Helen Koike Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, linux-sunxi@googlegroups.com, Mauro Carvalho Chehab , Rob Herring , Maxime Ripard , Chen-Yu Tsai , Yong Deng , Kishon Vijay Abraham I , Vinod Koul , Greg Kroah-Hartman , Philipp Zabel , Hans Verkuil , Sakari Ailus , Thomas Petazzoni , Hans Verkuil , kevin.lhopital@hotmail.com Subject: Re: [PATCH 00/14] Allwinner MIPI CSI-2 support for A31/V3s/A83T Message-ID: <20201104111137.GH285779@aptenodytes> References: <20201023174546.504028-1-paul.kocialkowski@bootlin.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="+Z7/5fzWRHDJ0o7Q" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org --+Z7/5fzWRHDJ0o7Q Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Helen, On Fri 30 Oct 20, 19:44, Helen Koike wrote: > Hi Paul, >=20 > 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-speci= fic > > controller. While the former uses the same MIPI D-PHY that is already s= upported > > for DSI, the latter embeds its own D-PHY. > >=20 > > 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 PH= Y API. > > This allows adding Rx support in the A31 D-PHY driver. > >=20 > > A few changes and fixes are applied to the A31 CSI controller driver, i= n order > > to support the MIPI CSI-2 use-case. > >=20 > > Follows is the V4L2 device topology representing the interactions betwe= en > > 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] > >=20 > > - 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] > >=20 > > - entity 8: ov5648 0-0036 (1 pad, 1 link) > > type V4L2 subdev subtype Sensor flags 0 > > device node name /dev/v4l-subdev0 >=20 > 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(). >=20 > 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 call= ing > 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. XXX > Also, sun6i-csi doesn't seem to be used by any board dts (it's declared o= n 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 ycbc= r:601 quantization:full-range] > > -> "sun6i-mipi-csi2":0 [ENABLED,IMMUTABLE] >=20 > If I understand correctly, this is very similar to ipu3: > sensor->bus->dma_engine >=20 > in the case of ipu3-cio2: > sensor->ipu3-csi2->ipu3-cio2 >=20 > 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 th= ink 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 su= pport parallel CSI. The DMA engine part alone from that controller is also used f= or 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 o= n 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. > On another note, I always wonder if we should expose the bus in the topol= ogy, 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. >=20 > 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, t= wo 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. Cheers, Paul > > Happy reviewing! > >=20 > > 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 > >=20 > > .../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,s= un6i-a31-mipi-csi2.yaml > > create mode 100644 Documentation/devicetree/bindings/media/allwinner,s= un8i-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/Makefi= le > > 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/K= config > > create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/M= akefile > > create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/s= un8i_a83t_dphy.c > > create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/s= un8i_a83t_dphy.h > > create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/s= un8i_a83t_mipi_csi2.c > > create mode 100644 drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/s= un8i_a83t_mipi_csi2.h > >=20 --=20 Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com --+Z7/5fzWRHDJ0o7Q Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEJZpWjZeIetVBefti3cLmz3+fv9EFAl+ijGgACgkQ3cLmz3+f v9GBXwgAjVuRycsMuOMUzhHXri4G20BBgDZQMfdouy8RuJ/ZhfBzwTDSLxJO2Yik fwYmb9vlc5aUBafplFZ0F2AkBQI65FwJqXzgMWpiwWEcUKtRtUe429qFHIWuRfx2 wapYJfBawJOFQ9Zk4NXVeqefDQbdtgZolYMomLE0cCo97s/hEdLXGbrIM0EpiU7a rczQRZ475D6c5haWlEZnQQxlaMDN6n2TjGzlSGyOc7n+AEj4uRAkWqObmZTmbl4x nGjsfkL2pgdPTZcSYt/mOMMMzudkzCpmH6a2ugwYWdWF3u0Sudl9Op5fV9qVaxgr JPOflqUjlhq3MUJLNEfVaHyPzfsOOw== =jv1S -----END PGP SIGNATURE----- --+Z7/5fzWRHDJ0o7Q--