linux-kernel - Re: [PATCH v2] i2c: imx-lpi2c: change to PIO mode in system-wide suspend/resume progress

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Message-ID: <CAEnQRZDcaWAQTLVHL1q+n2nhk3Cop2-fbOL+BqibrJHze2F9xw@mail.gmail.com>
Date: Thu, 20 Nov 2025 15:55:49 +0200
From: Daniel Baluta <daniel.baluta@...il.com>
To: Carlos Song <carlos.song@....com>
Cc: aisheng.dong@....com, andi.shyti@...nel.org, shawnguo@...nel.org, 
	s.hauer@...gutronix.de, kernel@...gutronix.de, frank.li@....com, 
	linux-i2c@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] i2c: imx-lpi2c: change to PIO mode in system-wide
 suspend/resume progress

On Thu, Nov 20, 2025 at 12:31 PM Carlos Song <carlos.song@....com> wrote:
>
> EDMA resume is in early stage and suspend is in late stage, but LPI2C
> resume and suspend are in NOIRQ stage. So LPI2C resource become ready
> earlier than EDMA. When IRQ enabled, immediately slave will trigger LPI2C
> to read data and the length meets the requirements for DMA usage, the DMA
> will be needed at this time. Within a very small time window, EDMA is
> still not resumed.
>
> If a system-wide suspend or resume transition is in progress. LPI2C should
> use PIO to transfer data not DMA to avoid issue caused by not ready DMA HW
> resource.
>
> Fixes: a09c8b3f9047 ("i2c: imx-lpi2c: add eDMA mode support for LPI2C")
> Signed-off-by: Carlos Song <carlos.song@....com>
> ---

For future patches please add here a small description of what changed since v1:
e.g

Changes since v1:
* updated commit message as per discussion with Frank.