linux-kernel - Re: [PATCH v3 1/2] clk: qcom: dispcc-sc7180: Only park display clks at init

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Message-ID: <ZtgOMJ2fmkZO8nDG@hovoldconsulting.com>
Date: Wed, 4 Sep 2024 09:37:20 +0200
From: Johan Hovold <johan@...nel.org>
To: Stephen Boyd <sboyd@...nel.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Stephen Boyd <swboyd@...omium.org>, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, patches@...ts.linux.dev,
	linux-clk@...r.kernel.org, Amit Pundir <amit.pundir@...aro.org>,
	Taniya Das <quic_tdas@...cinc.com>
Subject: Re: [PATCH v3 1/2] clk: qcom: dispcc-sc7180: Only park display clks
 at init

On Tue, Sep 03, 2024 at 12:55:07PM -0700, Stephen Boyd wrote:
> Quoting Johan Hovold (2024-09-02 00:15:53)
> > On Fri, Aug 30, 2024 at 03:29:22PM -0700, Stephen Boyd wrote:
> > > Quoting Stephen Boyd (2024-08-29 09:34:05)
> > 
> > > > It sounds like it's better to make the default always park at
> > > > registration time and special case the one or two places where that
> > > > isn't possible, i.e. USB because it has special rate requirements. So I
> > > > should just go back to v1 then and pile on the QUP patches.
> > > 
> > > I've done this now and I'll push out clk-fixes with the QUP patches.
> > 
> > I assumed you'd fix up all the other SoCs affected by this, but I only
> > saw fixes for sm8550, sm8650 and x1e80100 in your fixes branch.
> > 
> > Just sent a corresponding fix for sc8280xp, which I've confirmed also
> > needs this for QUP:
> 
> Thanks!
> 
> >         https://lore.kernel.org/lkml/20240902070830.8535-1-johan+linaro@kernel.org/
> > 
> > But what about the sm8550 USB issue? Don't the other platforms also need
> > a corresponding fix (e.g. for when booting from USB)?
> 
> I don't know. Are you seeing USB host issues on other platforms with
> shared RCG clk_ops for the USB clk? It looks inconsistent that sometimes
> there's a USB GDSC but the shared clk ops aren't used. If nothing is
> broken then let's work on the proper fix, which is parking RCGs when the
> GDSC is turned off so that turning on the GDSC always works. If USB is
> broken for you then send another patch.

I haven't noticed any USB issues on the two platforms I work on and
which both have USB GDSCs (sc8280xp and x1e80100), but then again I
don't test USB booting regularly (if that's when the issue show up).

I was hoping you would have a theory as to why things broke on sm8550 so
that you can reason about which platforms need this, rather than have
multiple users debug these issues and play whack-a-mole with incomplete
fixes.

I don't see anything SoC specific about the QUP fixes and assume early
console handover is now broken on all Qualcomm SoCs for example.

Johan