On Mon, Apr 17, 2023 at 6:23 PM Marek Vasut <marex@xxxxxxx> wrote: > > On 4/18/23 00:24, Adam Ford wrote: > > On Mon, Apr 17, 2023 at 3:08 PM Marek Vasut <marex@xxxxxxx> wrote: > >> > >> On 4/17/23 13:57, Adam Ford wrote: > >>> On Sun, Apr 16, 2023 at 5:13 PM Marek Vasut <marex@xxxxxxx> wrote: > >>>> > >>>> On 4/15/23 12:41, Adam Ford wrote: > >>>>> The high-speed clock is hard-coded to the burst-clock > >>>>> frequency specified in the device tree. However, when > >>>>> using devices like certain bridge chips without burst mode > >>>>> and varying resolutions and refresh rates, it may be > >>>>> necessary to set the high-speed clock dynamically based > >>>>> on the desired pixel clock for the connected device. > >>>> > >>>> The link rate negotiation should happen internally between the nearest > >>>> bridge and DSIM, so please add that to DRM core instead of hacking > >>>> around it by tweaking the HS clock again. > >>> > >>> I thought you tried to add something like this before and had some resistance. > >> > >> Yes, all my attempts were rejected by a single reviewer. I suspended my > >> efforts in that area for now. > >> > >>> The Pixel clock is set by the bridge already without any new code > >>> added to the DRM core.. I am just reading that value that's there, > >>> and setting the clock accordingly. I don't see how this is a hack. > >> > >> Assume you have a DSI-to-HDMI bridge attached to your DSIM bridge, it > >> operates in non-burst mode, like ADV7533 . How would you configure the > > > > I have an ADV7535 > > > >> HS clock rate for such a bridge in DT ? (hint: you cannot, because the > >> required clock comes from the EDID, which may not be available just yet) > > > > The whole idea is that you wouldn't want to or need to configure the > > clock speed in the device tree because it comes from the > > EDID->bridge->DSI. > > > > I've tested this configuration on imx8mm, imx8mn, and imx8mp and I can > > change the resolution and refresh rate on the fly and the DSI will > > automatically readjust accordingly. If you fixed the clock in the > > device tree, you wouldn't be able to do that, and that was the point > > of this patch. > > Uh, I retract my comment, I was clearly confused here and we're talking > about the same thing. I'm working on a V2 for this series. Are you OK with this if I update the commit message a bit to make it more clear? adam
