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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <df107382-5c9b-4568-b9e3-5a893070fad7@kernel.org>
Date: Mon, 26 Aug 2024 15:44:02 +0200
From: Konrad Dybcio <konradybcio@...nel.org>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
 Bjorn Andersson <andersson@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rajendra Nayak <quic_rjendra@...cinc.com>,
 Sibi Sankar <quic_sibis@...cinc.com>, Abel Vesa <abel.vesa@...aro.org>,
 Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
 linux-kernel@...r.kernel.org, Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH] clk: qcom: gcc-x1e80100: Don't use parking clk_ops for
 QUPs

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@...aro.org>
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.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@...nel.org>

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

Konrad