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From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	Andre Przywara <andre.przywara@arm.com>
Subject: Re: [PATCH v3 1/13] mmc: sunxi: Fix clock frequency change sequence
Date: Wed, 25 Jan 2017 09:26:02 +0100	[thread overview]
Message-ID: <20170125082602.llunpuqwsimtzkds@lukather> (raw)
In-Reply-To: <CAPDyKFp735=MMm02PKEt2iZmN0Afyp52_g-8hKxpW71hw2RyiQ@mail.gmail.com>

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Hi Ulf,

On Tue, Jan 24, 2017 at 09:12:07AM +0100, Ulf Hansson wrote:
> On 16 January 2017 at 17:56, Maxime Ripard
> <maxime.ripard@free-electrons.com> wrote:
> > The MMC and SD specifications documents that the clock frequency should
> > only be changed once gated.
> 
> Where?
> 
> >
> > The current code first modifies the parent clock, gates it and then
> > modifies the internal divider. This means that since the parent clock rate
> > might be changed, the bus clock might be changed as well before it is
> > gated, which breaks the specification.
> >
> > Move the gating before the parent rate modification.
> 
> This all makes perfect sense to me, however I am not sure you need to
> refer to the spec to justify these changes.

I can't find it anymore :/

I'll resend that patch reworking the commit log.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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  reply	other threads:[~2017-01-25  8:26 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-16 16:56 [PATCH v3 0/13] arm64: allwinner: a64: Enable MMC support Maxime Ripard
2017-01-16 16:56 ` [PATCH v3 1/13] mmc: sunxi: Fix clock frequency change sequence Maxime Ripard
2017-01-24  8:12   ` Ulf Hansson
2017-01-25  8:26     ` Maxime Ripard [this message]
2017-01-16 16:56 ` [PATCH v3 2/13] mmc: sunxi: Gate the clock when rate is 0 Maxime Ripard
     [not found]   ` <1f006fd86d1d9ad5eab0c0c9e435003055466a54.1484585798.git-series.maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-01-24  8:14     ` Ulf Hansson
2017-01-16 16:56 ` [PATCH v3 3/13] mmc: sunxi: Always set signal delay to 0 for A64 Maxime Ripard
2017-01-24  8:16   ` Ulf Hansson
2017-01-24  9:15     ` Andre Przywara
     [not found]     ` <CAPDyKFoatUWz0AwY6e73OCguDx70B1B5OAoPUYX-JDPsru+aZw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-01-25  9:10       ` Maxime Ripard
2017-01-16 16:56 ` [PATCH v3 4/13] mmc: sunxi: Enable the new timings for the A64 MMC controllers Maxime Ripard
2017-01-16 16:56 ` [PATCH v3 5/13] mmc: sunxi: Mask DATA0 when updating the clock Maxime Ripard
2017-01-24  8:18   ` Ulf Hansson
2017-01-25  9:16     ` Maxime Ripard
2017-01-16 16:56 ` [PATCH v3 6/13] mmc: sunxi: Add EMMC (MMC2) controller compatible Maxime Ripard
2017-01-16 16:56 ` [PATCH v3 7/13] mmc: sunxi: Add more debug messages Maxime Ripard
2017-01-24  8:22   ` Ulf Hansson
2017-01-25  9:16     ` Maxime Ripard
2017-01-16 16:56 ` [PATCH v3 8/13] arm64: allwinner: a64: Add MMC nodes Maxime Ripard
2017-01-16 19:16   ` Corentin Labbe
2017-01-25  9:17     ` Maxime Ripard
2017-01-16 16:56 ` [PATCH v3 9/13] arm64: allwinner: a64: Add MMC pinctrl nodes Maxime Ripard
2017-01-16 16:57 ` [PATCH v3 10/13] arm64: allwinner: a64: Increase the MMC max frequency Maxime Ripard
2017-01-16 16:57 ` [PATCH v3 11/13] arm64: allwinner: pine64: add MMC support Maxime Ripard
     [not found] ` <cover.a06ce1672d7a72ee7f9bbca46fdd223edd6b2313.1484585798.git-series.maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-01-16 16:57   ` [PATCH v3 12/13] arm64: allwinner: a64: add UART1 pin nodes Maxime Ripard
2017-01-16 16:57 ` [PATCH v3 13/13] arm64: allwinner: add BananaPi-M64 support Maxime Ripard
2017-01-23 10:58 ` [PATCH v3 0/13] arm64: allwinner: a64: Enable MMC support Maxime Ripard

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