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From: Konrad Dybcio <konradybcio@kernel.org>
To: Bryan O'Donoghue <bryan.odonoghue@linaro.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>,
	Rajendra Nayak <quic_rjendra@quicinc.com>,
	Sibi Sankar <quic_sibis@quicinc.com>,
	Abel Vesa <abel.vesa@linaro.org>,
	Konrad Dybcio <konradybcio@kernel.org>
Cc: linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Neil Armstrong <neil.armstrong@linaro.org>
Subject: Re: [PATCH] clk: qcom: gcc-x1e80100: Don't use parking clk_ops for QUPs
Date: Mon, 26 Aug 2024 15:44:02 +0200	[thread overview]
Message-ID: <df107382-5c9b-4568-b9e3-5a893070fad7@kernel.org> (raw)
In-Reply-To: <20240823-x1e80100-clk-fix-v1-1-0b1b4f5a96e8@linaro.org>

On 23.08.2024 2:58 PM, Bryan O'Donoghue wrote:
> 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@linaro.org>
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
> ---
> I ran into some junk on the x1e80100 serial port and asked around to see if
> someone had already found and fixed.
> 
> Neil pointed me at Stephen's fix for sm8550 which I found is also required
> to fix the same thing x1e80100.
> ---

Reviewed-by: Konrad Dybcio <konradybcio@kernel.org>

Mind also fixing up 8650 that seems to have this issue?

Konrad

  reply	other threads:[~2024-08-26 13:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-23 12:58 Bryan O'Donoghue
2024-08-26 13:44 ` Konrad Dybcio [this message]
2024-08-27 13:13   ` Bryan O'Donoghue
2024-08-27 18:02 ` Stephen Boyd
2024-08-27 18:16   ` Stephen Boyd

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