linux-kernel - Re: [PATCH] clk: qcom: gcc-x1e80100: Don't use parking clk

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Message-ID: <2156bd2a8bde7f07491ab9ed9cf1ee15.sboyd@kernel.org>
Date: Tue, 27 Aug 2024 11:02:48 -0700
From: Stephen Boyd <sboyd@...nel.org>
To: Abel Vesa <abel.vesa@...aro.org>, Bjorn Andersson <andersson@...nel.org>, Bryan O'Donoghue <bryan.odonoghue@...aro.org>, Konrad Dybcio <konradybcio@...nel.org>, Michael Turquette <mturquette@...libre.com>, Rajendra Nayak <quic_rjendra@...cinc.com>, Sibi Sankar <quic_sibis@...cinc.com>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, Neil Armstrong <neil.armstrong@...aro.org>, Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Subject: Re: [PATCH] clk: qcom: gcc-x1e80100: Don't use parking clk_ops for QUPs

Quoting Bryan O'Donoghue (2024-08-23 05:58:56)
> Per Stephen Boyd's explanation in the link below, QUP RCG clocks do not
> need to be parked when switching frequency. A side-effect in parking to a
> lower frequency can be a momentary invalid clock driven on an in-use serial
> peripheral.
> 
> This can cause "junk" to spewed out of a UART as a low-impact example. On
> the x1e80100-crd this serial port junk can be observed on linux-next.
> 
> Apply a similar fix to the x1e80100 Global Clock controller to remediate.
> 
> Link: https://lore.kernel.org/all/20240819233628.2074654-3-swboyd@chromium.org/
> Fixes: 161b7c401f4b ("clk: qcom: Add Global Clock controller (GCC) driver for X1E80100")
> Fixes: 929c75d57566 ("clk: qcom: gcc-sm8550: Mark RCGs shared where applicable")
> Suggested-by: Neil Armstrong <neil.armstrong@...aro.org>
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
> ---

Applied to clk-fixes