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

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Message-Id: <20251120103039.1824209-1-carlos.song@nxp.com>
Date: Thu, 20 Nov 2025 18:30:39 +0800
From: Carlos Song <carlos.song@....com>
To: aisheng.dong@....com,
	andi.shyti@...nel.org,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	carlos.song@....com,
	frank.li@....com
Cc: linux-i2c@...r.kernel.org,
	imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] i2c: imx-lpi2c: change to PIO mode in system-wide suspend/resume progress

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>
---
 drivers/i2c/busses/i2c-imx-lpi2c.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
index 2a0962a0b441..d882126c1778 100644
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -592,6 +592,13 @@ static bool is_use_dma(struct lpi2c_imx_struct *lpi2c_imx, struct i2c_msg *msg)
 	if (!lpi2c_imx->can_use_dma)
 		return false;
 
+	/*
+	 * A system-wide suspend or resume transition is in progress. LPI2C should use PIO to
+	 * transfer data to avoid issue caused by no ready DMA HW resource.
+	 */
+	if (pm_suspend_in_progress())
+		return false;
+
 	/*
 	 * When the length of data is less than I2C_DMA_THRESHOLD,
 	 * cpu mode is used directly to avoid low performance.
-- 
2.34.1