On 11/4/20 3:45 PM, Maxime Ripard wrote: > 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 > Thanks for the explanation :) Helen
