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Subject: Re: [PATCH v2 6/6] PM / devfreq: Add a driver for the sun8i/sun50i
 MBUS
To:     Samuel Holland <samuel@sholland.org>,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Maxime Ripard <mripard@kernel.org>,
        Chen-Yu Tsai <wens@csie.org>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Rob Herring <robh+dt@kernel.org>
Cc:     Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
        linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org
From:   Chanwoo Choi <cw00.choi@samsung.com>
Organization: Samsung Electronics
Message-ID: <b6650bd2-7459-2604-f6ff-6eb6df739412@samsung.com>
Date:   Fri, 15 Oct 2021 17:28:45 +0900
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        <CGME20211004012806epcas1p1ba8ec0edc024a14e520865f689773be8@epcas1p1.samsung.com>
        <20211004012739.39053-7-samuel@sholland.org>
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Hi Samuel,

On 10/4/21 10:27 AM, Samuel Holland wrote:
> This driver works by adjusting the divider on the DRAM controller's
> module clock. Thus there is no fixed set of OPPs, only "full speed" down
> to "quarter speed" (or whatever the maximum divider is on that variant).
> 
> It makes use of the MDFS hardware in the MBUS, in "DFS" mode, which
> takes care of updating registers during the critical section while DRAM
> is inaccessible.
> 
> This driver should support several sunxi SoCs, starting with the A33,
> which have a DesignWare DDR3 controller with merged PHY register space
> and the matching MBUS register layout (so not A63 or later). However,
> the driver has only been tested on the A64/H5, so those are the only
> compatibles enabled for now.
> 
> Signed-off-by: Samuel Holland <samuel@sholland.org>
> ---
>  drivers/devfreq/Kconfig          |   8 +
>  drivers/devfreq/Makefile         |   1 +
>  drivers/devfreq/sun8i-a33-mbus.c | 511 +++++++++++++++++++++++++++++++
>  3 files changed, 520 insertions(+)
>  create mode 100644 drivers/devfreq/sun8i-a33-mbus.c


(snip)

Looks good to me.

Acked-by: Chanwoo Choi <cw00.choi@samsung.com>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics