linux-kernel - Re: [PATCH 1/3] clk: qcom: smd-rpm: Add rate hooks for clk_smd_rpm_branch

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 for Android: free password hash cracker in your pocket

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

Message-ID: <163165658855.763609.14080313241484048687@swboyd.mtv.corp.google.com>
Date:   Tue, 14 Sep 2021 14:56:28 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Shawn Guo <shawn.guo@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Loic Poulain <loic.poulain@...aro.org>,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shawn Guo <shawn.guo@...aro.org>
Subject: Re: [PATCH 1/3] clk: qcom: smd-rpm: Add rate hooks for clk_smd_rpm_branch_ops

Quoting Shawn Guo (2021-09-13 19:55:52)
> On QCM2290 platform, the clock xo_board runs at 38400000, while the
> child clock bi_tcxo needs to run at 19200000.  That said,
> clk_smd_rpm_branch_ops needs the capability of setting rate. Add rate
> hooks into clk_smd_rpm_branch_ops to make it possible.

This doesn't sound right. The branch is a simple on/off. If xo_board is
38.4MHz, then there is an internal divider in the SoC that makes bi_tcxo
(i.e. the root of the entire clk tree) be 19.2MHz. We don't model the
divider, I guess because it isn't very important to. Instead, we tack on
a divider field and implement recalc_rate op. See clk-rpmh.c in the qcom
directory for this.