Messages in this thread | | | Date | Mon, 2 Oct 2023 11:13:00 +0200 | Subject | Re: [PATCH 2/2] clk: qcom: gcc-sc8280xp: Don't keep display AHB clocks always-on | From | Konrad Dybcio <> |
| |
On 10/2/23 10:34, Johan Hovold wrote: > On Sat, Sep 30, 2023 at 06:44:47PM +0200, Konrad Dybcio wrote: >> On 9/30/23 11:39, Johan Hovold wrote: >>> On Fri, Sep 29, 2023 at 03:38:53PM +0200, Konrad Dybcio wrote: >>>> These clocks are consumed by the dispcc[01] clock controllers, so there's >>>> no reason to keep them on from gcc probe. Remove that hack. >>> >>> Eh, how did you test this patch? > >> Oehh you're right, I didn't notice that I still had clk_ignore_unused :/ > > That doesn't matter since these clocks are never even registered with > the clock framework. That's the point, if it was missing and was not enabled I would have noticed display not working (unless the bootloader left it on, which it did for at least the mdss instance with the eDP panel)
> > But you'd notice that if you try to verify the clock state by looking at > /sys/kernel/debug/clk/clk_summary for example. > >>> The GCC_DISP_AHB_CLK clocks are not modelled by the clock driver >>> currently so nothing is guaranteeing them to be enabled if we were to >>> apply this patch. They just happen to be left on by the bootloader on >>> some machines currently (well at least one of them is on one machine). > >> What fooled me is that despite not being modeled by the clock driver, it >> is defined in bindings and referenced in the device tree. >> >> Another thing I'll fix up! > > Right, a number of Qualcomm SoCs apparently fail to register these > clocks. You should start by determining why that is as I assume (hope) > it was done for a reason. The reason is, downstream lazily enables clocks because people decided they don't leak much power and are still enabled after a clock controller reset (or something) and we started blindly copying that around 2017 :/
> > Then the Qualcomm drivers use sloppy bulk clock look-up and enable so > that an integrator would never even notice when clocks are missing. Once > the clocks are registered, that could be tightened up as well. Yeah the current state of things is not great.
Konrad
| |