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From: Wolfram Sang <wsa@kernel.org>
To: "Marek Behún" <kabel@kernel.org>
Cc: linux-i2c@vger.kernel.org,
	Gregory CLEMENT <gregory.clement@bootlin.com>,
	Samuel Holland <samuel@sholland.org>,
	Ondrej Jirman <megous@megous.com>
Subject: Re: [PATCH] i2c: mv64xxx: Fix random system lock caused by runtime PM
Date: Thu, 15 Apr 2021 22:13:27 +0200
Message-ID: <20210415201327.GD2360@kunai> (raw)
In-Reply-To: <20210408020000.21914-1-kabel@kernel.org>


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On Thu, Apr 08, 2021 at 04:00:00AM +0200, Marek Behún wrote:
> I noticed a weird bug with this driver on Marvell CN9130 Customer
> Reference Board.
> 
> Sometime after boot, the system locks with the following message:
>  [104.071363] i2c i2c-0: mv64xxx: I2C bus locked, block: 1, time_left: 0
> 
> The system does not respond afterwards, only warns about RCU stalls.
> 
> This first appeared with commit e5c02cf54154 ("i2c: mv64xxx: Add runtime
> PM support").
> 
> With further experimentation I discovered that adding a delay into
> mv64xxx_i2c_hw_init() fixes this issue. This function is called before
> every xfer, due to how runtime PM works in this driver. It seems that in
> order to work correctly, a delay is needed after the bus is reset in
> this function.
> 
> Since there already is a known erratum with this controller needing a
> delay, I assume that this is just another place this needs to be
> applied. Therefore I apply the delay only if errata_delay is true.
> 
> Signed-off-by: Marek Behún <kabel@kernel.org>

Applied to for-current, thanks!


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      parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-08  2:00 Marek Behún
2021-04-10 16:47 ` Marek Behún
2021-04-13 19:58 ` Wolfram Sang
2021-04-14 13:28   ` Gregory CLEMENT
2021-04-14 14:29     ` Marek Behún
2021-04-14 13:42   ` Samuel Holland
2021-04-15 20:13 ` Wolfram Sang [this message]

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