linux-kernel - Re: [PATCH v3] i2c: imx-lpi2c: change to PIO mode in system-wide suspend/resume progress

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Message-ID: <aWeFHNiNuHLdhZrO@ninjato>
Date: Wed, 14 Jan 2026 12:59:24 +0100
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Carlos Song <carlos.song@....com>
Cc: frank.li@....com, aisheng.dong@....com, andi.shyti@...nel.org,
	shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
	linux-i2c@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] i2c: imx-lpi2c: change to PIO mode in system-wide
 suspend/resume progress

On Fri, Nov 21, 2025 at 11:00:30AM +0800, Carlos Song wrote:
> EDMA resumes early and suspends late in the system power transition
> sequence, while LPI2C enters the NOIRQ stage for both suspend and resume.
> This means LPI2C resources become available before EDMA is fully resumed.
> Once IRQs are enabled, a slave device may immediately trigger an LPI2C
> transfer. If the transfer length meets DMA requirements, the driver will
> attempt to use EDMA even though EDMA may still be unavailable.
> 
> This timing gap can lead to transfer failures. To prevent this, force
> LPI2C to use PIO mode during system-wide suspend and resume transitions.
> This reduces dependency on EDMA and avoids using an unready DMA resource.
> 
> Fixes: a09c8b3f9047 ("i2c: imx-lpi2c: add eDMA mode support for LPI2C")
> Signed-off-by: Carlos Song <carlos.song@....com>
> Reviewed-by: Frank Li <Frank.Li@....com>

Applied to for-current, thanks!