From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933054AbdBHJrx (ORCPT ); Wed, 8 Feb 2017 04:47:53 -0500 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:44343 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932960AbdBHJru (ORCPT ); Wed, 8 Feb 2017 04:47:50 -0500 Message-ID: <1486547235.2309.15.camel@pengutronix.de> Subject: Re: [PATCH v3 13/24] platform: add video-multiplexer subdevice driver From: Philipp Zabel To: Sakari Ailus Cc: Steve Longerbeam , robh+dt@kernel.org, mark.rutland@arm.com, shawnguo@kernel.org, kernel@pengutronix.de, fabio.estevam@nxp.com, linux@armlinux.org.uk, mchehab@kernel.org, hverkuil@xs4all.nl, nick@shmanahar.org, markus.heiser@darmarIT.de, laurent.pinchart+renesas@ideasonboard.com, bparrot@ti.com, geert@linux-m68k.org, arnd@arndb.de, sudipm.mukherjee@gmail.com, minghsiu.tsai@mediatek.com, tiffany.lin@mediatek.com, jean-christophe.trotin@st.com, horms+renesas@verge.net.au, niklas.soderlund+renesas@ragnatech.se, robert.jarzmik@free.fr, songjun.wu@microchip.com, andrew-ct.chen@mediatek.com, gregkh@linuxfoundation.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, devel@driverdev.osuosl.org, Sascha Hauer , Steve Longerbeam , Sebastian Reichel Date: Wed, 08 Feb 2017 10:47:15 +0100 In-Reply-To: <20170207204617.GD13854@valkosipuli.retiisi.org.uk> References: <1483755102-24785-1-git-send-email-steve_longerbeam@mentor.com> <1483755102-24785-14-git-send-email-steve_longerbeam@mentor.com> <20170207204617.GD13854@valkosipuli.retiisi.org.uk> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9-1+b1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:3ad5:47ff:feaf:1a17 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sakari, On Tue, 2017-02-07 at 22:46 +0200, Sakari Ailus wrote: > Hi Steve, > > On Fri, Jan 06, 2017 at 06:11:31PM -0800, Steve Longerbeam wrote: > > From: Philipp Zabel > > > > This driver can handle SoC internal and external video bus multiplexers, > > controlled either by register bit fields or by a GPIO. The subdevice > > passes through frame interval and mbus configuration of the active input > > to the output side. > > > > Signed-off-by: Sascha Hauer > > Signed-off-by: Philipp Zabel > > > > -- > > > > - fixed a cut&paste error in vidsw_remove(): v4l2_async_register_subdev() > > should be unregister. > > > > - added media_entity_cleanup() and v4l2_device_unregister_subdev() > > to vidsw_remove(). > > > > - there was a line left over from a previous iteration that negated > > the new way of determining the pad count just before it which > > has been removed (num_pads = of_get_child_count(np)). > > > > - Philipp Zabel has developed a set of patches that allow adding > > to the subdev async notifier waiting list using a chaining method > > from the async registered callbacks (v4l2_of_subdev_registered() > > and the prep patches for that). For now, I've removed the use of > > v4l2_of_subdev_registered() for the vidmux driver's registered > > callback. This doesn't affect the functionality of this driver, > > but allows for it to be merged now, before adding the chaining > > support. > > > > Signed-off-by: Steve Longerbeam > > --- > > .../bindings/media/video-multiplexer.txt | 59 +++ > > drivers/media/platform/Kconfig | 8 + > > drivers/media/platform/Makefile | 2 + > > drivers/media/platform/video-multiplexer.c | 472 +++++++++++++++++++++ > > 4 files changed, 541 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/media/video-multiplexer.txt > > create mode 100644 drivers/media/platform/video-multiplexer.c > > > > diff --git a/Documentation/devicetree/bindings/media/video-multiplexer.txt b/Documentation/devicetree/bindings/media/video-multiplexer.txt > > new file mode 100644 > > index 0000000..9d133d9 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/media/video-multiplexer.txt > > @@ -0,0 +1,59 @@ > > +Video Multiplexer > > +================= > > + > > +Video multiplexers allow to select between multiple input ports. Video received > > +on the active input port is passed through to the output port. Muxes described > > +by this binding may be controlled by a syscon register bitfield or by a GPIO. > > + > > +Required properties: > > +- compatible : should be "video-multiplexer" > > +- reg: should be register base of the register containing the control bitfield > > +- bit-mask: bitmask of the control bitfield in the control register > > +- bit-shift: bit offset of the control bitfield in the control register > > +- gpios: alternatively to reg, bit-mask, and bit-shift, a single GPIO phandle > > + may be given to switch between two inputs > > +- #address-cells: should be <1> > > +- #size-cells: should be <0> > > +- port@*: at least three port nodes containing endpoints connecting to the > > + source and sink devices according to of_graph bindings. The last port is > > + the output port, all others are inputs. > > + > > +Example: > > + > > +syscon { > > + compatible = "syscon", "simple-mfd"; > > + > > + mux { > > Could you use standardised properties for this, i.e. ones defined in > Documentation/devicetree/bindings/media/video-interfaces.txt ? What do you mean? Should we add the optional bus-width property to describe the bit width of the parallel bus even though the driver doesn't care about any of the properties? > This is very similar to another patch "[PATCH] devicetree: Add video bus > switch" posted by Pavel Machek recently. The problem with that is also > similar than with this one: how to pass the CSI-2 bus configuration to the > receiver. > > There's some discussion here: > > [Added Sebastian do Cc:] Yes, this is essentially the same driver, except that this driver also handles MMIO-bitfield controlled muxes, and that the actual physical bus (which the drivers currently don't care about) is MIPI CSI-2 in the other case, and parallel this one. They should probably be combined, or maybe split into two separate drivers (MMIO controlled mux, GPIO controlled switch), possibly using the same v4l2_subdev boilerplate. > As Laurent already suggested, I think we should have a common solution for > the problem that, besides conveying the bus parameters to the receiver, also > encompasses CSI-2 virtual channels and data types. Yes, that seems to be necessary, as certainly we can't configure the mux output bus parameters in DT to a fixed setting. > That would mean finishing the series of patches in the branch I believe > Laurent already quoted here. regards Philipp