From: Robert Foss <robert.foss@linaro.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: agross@kernel.org, mturquette@baylibre.com, sboyd@kernel.org,
robh+dt@kernel.org, krzk+dt@kernel.org, jonathan@marek.ca,
tdas@codeaurora.org, anischal@codeaurora.org,
linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Subject: Re: [PATCH v2 2/8] clk: Introduce CLK_ASSUME_ENABLED_WHEN_UNUSED
Date: Tue, 3 May 2022 18:23:45 +0200 [thread overview]
Message-ID: <CAG3jFysjzTMJM=DbLGNXBfWYjQKxxRvGQMZp6GOL7uBvRUwRYw@mail.gmail.com> (raw)
In-Reply-To: <YnFEGzTQMsNpczai@builder.lan>
On Tue, 3 May 2022 at 17:02, Bjorn Andersson <bjorn.andersson@linaro.org> wrote:
>
> On Tue 03 May 08:04 CDT 2022, Robert Foss wrote:
>
> > From: Bjorn Andersson <bjorn.andersson@linaro.org>
> >
> > Some clock implementations doesn't provide means of implementing
> > is_enabled(), but still requires to be explicitly disabled when found
> > unused as part of clk_disable_unused().
> >
> > One such set of clocks are Qualcomm's display RCGs. These can be enabled
> > and disabled automatically by the hardware, so it's not possible to
> > reliably query their configuration. Further more, these clocks need to
> > be disabled when unused, to allow them to be "parked" onto a safe
> > parent. Failure to disable the RCG results in the hardware locking up as
> > clk_disable_unused() traverses up the tree and turns off its source
> > clocks.
> >
> > Add a new flag, CLK_ASSUME_ENABLED_BOOT, which clock drivers can use to
> > signal that these clocks should be disabled even if they don't implement
> > the is_enabled() ops.
> >
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > ---
> >
>
> I discussed this with Stephen a while ago and we agreed that in a
> sufficiently complex system with kernel modules booting without
> clk_ignore_unused simply isn't supported.
>
> We will have to design something better. So please drop this patch from
> the series.
Ack
next prev parent reply other threads:[~2022-05-03 16:24 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-03 13:04 [PATCH v2 1/8] clk: qcom: rcg2: Cache rate changes for parked RCGs Robert Foss
2022-05-03 13:04 ` [PATCH v2 2/8] clk: Introduce CLK_ASSUME_ENABLED_WHEN_UNUSED Robert Foss
2022-05-03 15:02 ` Bjorn Andersson
2022-05-03 16:23 ` Robert Foss [this message]
2022-05-03 13:04 ` [PATCH v2 3/8] clk: qcom: sm8250-dispcc: Flag shared RCGs as assumed enable Robert Foss
2022-05-03 13:04 ` [PATCH v2 4/8] clk: qcom: add support for SM8350 GPUCC Robert Foss
2022-05-03 17:21 ` Bjorn Andersson
2022-05-03 20:39 ` Jonathan Marek
2022-05-04 12:24 ` Robert Foss
2022-05-03 13:04 ` [PATCH v2 5/8] dt-bindings: clock: Add Qcom SM8350 GPUCC bindings Robert Foss
2022-05-03 17:24 ` Bjorn Andersson
2022-05-03 13:04 ` [PATCH v2 6/8] clk: qcom: add support for SM8350 DISPCC Robert Foss
2022-05-03 17:25 ` Bjorn Andersson
2022-05-03 17:47 ` Robert Foss
2022-05-03 13:04 ` [PATCH v2 7/8] dt-bindings: clock: Add Qcom SM8350 DISPCC bindings Robert Foss
2022-05-03 17:26 ` Bjorn Andersson
2022-05-03 17:47 ` Robert Foss
2022-05-03 13:04 ` [PATCH v2 8/8] arm64: dts: qcom: sm8350: Add DISPCC node Robert Foss
2022-05-03 17:27 ` Bjorn Andersson
2022-05-03 15:01 ` [PATCH v2 1/8] clk: qcom: rcg2: Cache rate changes for parked RCGs Bjorn Andersson
2022-05-03 16:23 ` Robert Foss
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