linux-kernel - Re: [PATCH v2 1/5] clk: qcom: apss-ipq-pll: drop 'alpha_en

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Message-ID: <3qdbri4ymlbzn7dcl3dxyggyjberohytpoq2qe3zj2lxwq5hj6@n5f3gkaqpsu4>
Date: Mon, 28 Oct 2024 23:31:43 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Gabor Juhos <j4g8y7@...il.com>
Cc: Bjorn Andersson <andersson@...nel.org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org, 
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/5] clk: qcom: apss-ipq-pll: drop 'alpha_en_mask'
 from IPQ5018 PLL config

On Mon, Oct 28, 2024 at 07:48:15PM +0100, Gabor Juhos wrote:
> Since neither 'alpha' nor 'alpha_hi' is defined in the configuration,
> those will be initialized with zero values  implicitly. By using zero
> alpha values, the output rate of the PLL will be the same whether
> alpha mode is enabled or not.
> 
> Remove the superfluous initialization of the 'alpha_en_mask' member
> to make it clear that enabling alpha mode is not required to get the
> desired output rate.
> 
> Despite that enabling alpha mode is not needed for the initial
> configuration, the set_rate() op might require that it is enabled
> already. In this particular case however, the
> clk_alpha_pll_stromer_set_rate() function will get reset the
> ALPHA_EN bit when the PLL's rate changes, so dropping 'alpha_en_mask'
> is safe.
> 
> No functional changes, the initial rate of the PLL is the same both
> before and after the patch.
> 
> Tested on TP-Link Archer AX55 v1 (IPQ5018).
> 
> Signed-off-by: Gabor Juhos <j4g8y7@...il.com>
> ---
> Changes in v2:
>   - extend the commit message to indicate that dropping 'alpha_en_mask' is safe
>   - Link to v1: https://lore.kernel.org/r/20241021-alpha-mode-cleanup-v1-1-55df8ed73645@gmail.com
> ---
>  drivers/clk/qcom/apss-ipq-pll.c | 1 -
>  1 file changed, 1 deletion(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

-- 
With best wishes
Dmitry