On Wed, Nov 04, 2020 at 01:38:08PM -0300, Helen Koike wrote: > > > On 11/4/20 8:17 AM, Paul Kocialkowski wrote: > > Hi, > > > > On Mon 02 Nov 20, 10:21, Maxime Ripard wrote: > >> On Fri, Oct 30, 2020 at 07:45:18PM -0300, Helen Koike wrote: > >>> On 10/23/20 2:45 PM, Paul Kocialkowski wrote: > >>>> The A31 MIPI CSI-2 controller is a dedicated MIPI CSI-2 controller > >>>> found on Allwinner SoCs such as the A31 and V3/V3s. > >>>> > >>>> It is a standalone block, connected to the CSI controller on one side > >>>> and to the MIPI D-PHY block on the other. It has a dedicated address > >>>> space, interrupt line and clock. > >>>> > >>>> Currently, the MIPI CSI-2 controller is hard-tied to a specific CSI > >>>> controller (CSI0) but newer SoCs (such as the V5) may allow switching > >>>> MIPI CSI-2 controllers between CSI controllers. > >>>> > >>>> It is represented as a V4L2 subdev to the CSI controller and takes a > >>>> MIPI CSI-2 sensor as its own subdev, all using the fwnode graph and > >>>> media controller API. > >>> > >>> Maybe this is a bad idea, but I was thinking: > >>> This driver basically just turn on/off and catch some interrupts for errors, > >>> and all the rest of v4l2 config you just forward to the next subdevice > >>> on the pipeline. > >>> > >>> So instead of exposing it as a subdevice, I was wondering if modeling > >>> this driver also through the phy subsystem wouldn't be cleaner, so > >>> you won't need all the v4l2 subdevice/topology boilerplate code that > >>> it seems you are not using (unless you have plans to add controls or > >>> some specific configuration on this node later). > >>> > >>> But this would require changes on the sun6i-csi driver. > >>> > >>> What do you think? > >> > >> Eventually we'll need to filter the virtual channels / datatypes I > >> guess, so it's definitely valuable to have it in v4l2 > > Which kind of datatypes? MIPI-CSI datatypes. Each packet on the MIPI-CSI bus is assigned a virtual channel and data type so that you can multiplex multiple streams (like a 3d camera would send for example, through the virtual channels) and data types (like frames and metadata) and MIPI-CSI controllers usually allow to filter them based on what you want. > I ask to know if this shouldn't be configured through the video node > instead of subdevice. Not really, some setups have a mux that can split the multiple virtual channels to multiple video nodes for example. > Regarding channels, we had a discussion to implement it through the video > node (and not subdevice) [1]. But we discussed about blitters and multi-scalers, > so now I'm wondering if we could use the same API for mipi-csi virtual channels > in the video entity device, or if it doesn't apply and we need another API > for that in a subdevice instead. > > [1] https://patchwork.linuxtv.org/project/linux-media/cover/20200717115435.2632623-1-helen.koike@xxxxxxxxxxxxx/ There's already an API to deal with MIPI-CSI virtual channels: https://patchwork.kernel.org/project/linux-renesas-soc/cover/20190328200608.9463-1-jacopo+renesas@xxxxxxxxxx/ Maxime
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