linux-kernel - Re: [PATCH] clk: Fix invalid execution of clk_set

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Message-ID: <0ea59af3c891859681cac378eaface75.sboyd@kernel.org>
Date: Thu, 14 Nov 2024 15:17:19 -0800
From: Stephen Boyd <sboyd@...nel.org>
To: Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org>, Michael Turquette <mturquette@...libre.com>, chuan.liu@...ogic.com
Cc: linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, Chuan Liu <chuan.liu@...ogic.com>
Subject: Re: [PATCH] clk: Fix invalid execution of clk_set_rate

Quoting Chuan Liu via B4 Relay (2024-09-09 22:53:44)
> From: Chuan Liu <chuan.liu@...ogic.com>
> 
> Some clocks have rates that can be changed elsewhere, so add a flag
> CLK_GET_RATE_NOCACHE(such as scmi_clk) to these clocks to ensure that
> the real-time rate is obtained.
> 
> When clk_set_rate is called, it is returned if the request to set rate
> is consistent with the current rate. Getting the current rate in
> clk_set_rate returns the rate stored in clk_core. CLK_GET_RATE_NOCACHE
> does not take effect here.
> 
> Signed-off-by: Chuan Liu <chuan.liu@...ogic.com>

This looks obviously correct but I'm worried that it will cause some
problem somewhere. It would be nice if there were some kunit tests
associated with this. The worst case situation is that we recalc rates
if the CLK_GET_RATE_NOCACHE flag is set, right? I guess I'll just apply
this as a cleanup for the next merge window and see if it causes
problems for anyone.