linux-kernel - Re: [PATCH 1/1] clk: socfpga: gate: Fix of by factor 2 for serial console

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Date:   Thu, 5 Oct 2023 13:34:01 +0200
From:   Maxime Ripard <mripard@...nel.org>
To:     Benedikt Spranger <b.spranger@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Dinh Nguyen <dinguyen@...nel.org>
Subject: Re: [PATCH 1/1] clk: socfpga: gate: Fix of by factor 2 for serial
 console

Hi,

On Thu, Oct 05, 2023 at 11:59:27AM +0200, Benedikt Spranger wrote:
> Commit 9607beb917df ("clk: socfpga: gate: Add a determine_rate hook")
> introduce a specific determine_rate hook. As a result the calculated
> clock for the serial IP is off by factor 2 after that i.e. if the system
> configures a baudrate of 115200 it is set physicaly to 57600.

Where is that factor 2 coming from?

> Change the determine_rate hook to the reparent variant
> __clk_mux_determine_rate() to fix the issue.

It's also not clear to me why that would fix anything. This patch should
only make the old behaviour explicit, could you expand a bit on what
happens?

Thanks!
Maxime

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