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Message-ID: <20181128102212.4sodbbk6uu52nug3@flea>
Date: Wed, 28 Nov 2018 11:22:12 +0100
From: Maxime Ripard <maxime.ripard@...tlin.com>
To: Chen-Yu Tsai <wens@...e.org>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>,
Alessandro Zummo <a.zummo@...ertech.it>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
linux-arm-kernel@...ts.infradead.org, linux-rtc@...r.kernel.org,
linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH 06/15] rtc: sun6i: Add support for different variants
On Wed, Nov 28, 2018 at 05:30:03PM +0800, Chen-Yu Tsai wrote:
> Amongst the Allwinner SoCs that have seen some kind of coverage by the
> linux-sunxi community, whether it be mainline Linux or U-boot support,
> or just available datasheets, most newer chips use the RTC design first
> seen in the A31 (sun6i).
>
> Overall there have been some minor differences. This patch covers the
> following:
>
> - average clock rate of the internal RC oscillator
> + presence of fixed and adjustable prescaler for this clock
> - availability of an external (to the SoC) clock output
>
> One major difference regarding the H6 is the 24 MHz crystal is now
> routed through the RTC, as a digitally compensated oscillator (DCXO).
> This is not covered in this patch and will be supported later.
>
> Other differences are either unrelated to RTC or clock functionality,
> such as boot or crypto related registers, or the driver simply doesn't
> use the feature in question. One example of the latter is the
> calibration function for the RC oscillator. We consider this clock to
> be very bad and avoid using it.
>
> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
Acked-by: Maxime Ripard <maxime.ripard@...tlin.com>
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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