linux-kernel - Re: [PATCH] clk: sunxi-ng: sun6i-a31: Force AHB1 clock to use PLL6 as parent

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Message-Id: <20161018095044.d1664c4935ad13007453fb35@free.fr>
Date:   Tue, 18 Oct 2016 09:50:44 +0200
From:   Jean-Francois Moine <moinejf@...e.fr>
To:     Chen-Yu Tsai <wens@...e.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        linux-sunxi@...glegroups.com, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: sunxi-ng: sun6i-a31: Force AHB1 clock to use PLL6
 as parent

On Tue, 18 Oct 2016 13:42:09 +0800
Chen-Yu Tsai <wens@...e.org> wrote:

> On the A31, the DMA engine only works if AHB1 is clocked from PLL6.
> In addition, the hstimer is clocked from AHB1, and if AHB1 is clocked
> from the CPU clock, and cpufreq is working, we get an unstable timer.
> 
> Force the AHB1 clock to use PLL6 as its parent. Previously this was done
> in the device tree with the assigned-clocks and assigned-clocks-parent
> bindings. However with this new monolithic driver, the system critical
> clocks aren't exported through the device tree. The alternative is to
> force this setting in the driver before the clocks are registered.

It should be simpler to export the constant (CLK_AHB1) instead of
adding code...

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/