On Mon, May 15, 2023 at 04:22:38PM +0200, AngeloGioacchino Del Regno wrote: > Il 15/05/23 15:36, Julien Stephan ha scritto: > > On Mon, May 15, 2023 at 02:22:52PM +0200, AngeloGioacchino Del Regno wrote: > > > Il 15/05/23 11:05, Julien Stephan ha scritto: > > ..snip.. > > > > + port->is_cdphy = of_property_read_bool(dev->of_node, "mediatek,is_cdphy"); > > > > > > This driver doesn't support C-PHY mode, so you either add support for that, or in > > > my opinion you should simply refuse to probe it, as it is *dysfunctional* for the > > > unsupported case (and might even introduce unstabilities). > > > > > > /* At the moment, only D-PHY mode is supported */ > > > if (!port->is_cdphy) > > > return -EINVAL; > > > > > > Also, please don't use underscores for devicetree properties: "mediatek,is-cdphy" > > > is fine. > > > > > Hi Angelo, > > You are right this driver does not support C-PHY mode, but some of the > > PHYs themselves support BOTH C-PHY AND D-PHY. The idea of `is_cdphy` variable > > is to know if the CSI port supports BOTH C-PHY AND D-PHY or only DPHY. > > For example mt8365 has 2 PHYs: CSI0 and CSI1. CSI1 support only D-PHY, > > while CSI0 can be configured in C-PHY or D-PHY. Registers for CD-PHY and > > D-PHY are almost identical, except that CD-PHY compatible has some extra > > bitfields to configure properly the mode and the lanes (because supporting > > trios for CD-PHY). > > If C-PHY support is eventually added into the driver, I think we will need > > another variable such as `mode` to know the mode. I was also thinking > > of adding a phy argument to determine if the mode is C-PHY or D-PHY. > > > > So here, I don't want to stop the probe if `is_cdphy` variable is set to > > true. Does it make sense ? > > > > Comments in the code convinced me that the other PHYs providing only C or D PHY > support weren't compatible at all with this driver. > > I got it now - but at this point can you please add a comment in the code actually > clarifying that this driver supports both PHYs providing *only* D-PHY and ones > providing selectable C-or-D PHY? > > That clarified, it would not make sense to stop probing if it's not a CDPHY because > as you said there might be a D-only PHY that would be actually supported here. > > Regards, > Angelo > > Ok, I will add a comment in the code to make it more clear. Regards Julien
