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From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: Jonathan Bakker <xc-racer2@live.ca>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, <patches@opensource.cirrus.com>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] regulator: wm8994: Add an off-on delay for WM8994 variant
Date: Mon, 28 Mar 2022 13:11:32 +0000	[thread overview]
Message-ID: <20220328131132.GI38351@ediswmail.ad.cirrus.com> (raw)
In-Reply-To: <CY4PR04MB056771CFB80DC447C30D5A31CB1D9@CY4PR04MB0567.namprd04.prod.outlook.com>

On Sun, Mar 27, 2022 at 06:01:54PM -0700, Jonathan Bakker wrote:
> As per Table 130 of the wm8994 datasheet at [1], there is an off-on
> delay for LDO1 and LDO2.  In the wm8958 datasheet [2], I could not
> find any reference to it.  I could not find a wm1811 datasheet to
> double-check there, but as no one has complained presumably it works
> without it.
> 
> This solves the issue on Samsung Aries boards with a wm8994 where
> register writes fail when the device is powered off and back-on
> quickly.
> 
> [1] https://statics.cirrus.com/pubs/proDatasheet/WM8994_Rev4.6.pdf
> [2] https://statics.cirrus.com/pubs/proDatasheet/WM8958_v3.5.pdf
> 
> Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
> ---

I can confirm the 1811 also doesn't mention the cycle time in the
datasheet. So that checks out.

Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>

Part of me wonders if we should just apply it to 1811 and 8958
anyway, I suspect they have the same IP for the LDO and its just
the datasheets never got updated. I had a go chasing the apps guys
here but we are a little short on people who remember details of
these parts. So I guess we trust the datasheets for now, unless
you have any strong feelings, Mark?

Thanks,
Charles

  reply	other threads:[~2022-03-28 13:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-27 22:15 [PATCH] regulator: wm8994: Add an off-on delay for WM8994 variant Jonathan Bakker
2022-03-27 22:48 ` Mark Brown
2022-03-28  1:01   ` [PATCH v2] " Jonathan Bakker
2022-03-28 13:11     ` Charles Keepax [this message]
2022-03-28 14:36       ` Mark Brown
2022-03-28 14:59         ` Charles Keepax
2022-04-05  9:32     ` Mark Brown

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