linux-next: manual merge of the i2c-rust tree with the origin tree

linux-next: manual merge of the i2c-rust tree with the origin tree

[Mark Brown]

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Hi all,

Today's linux-next merge of the i2c-rust tree got a conflict in:

  drivers/i2c/busses/i2c-imx-lpi2c.c

between commits:

  d1f112e2fa9b7 ("i2c: busses: drop redundant dev_err_probe() around irq helpers")
  cbd043b00ee3f ("i2c: imx-lpi2c: properly unwind resources on probe failure")
  a4c419356a333 ("i2c: imx-lpi2c: reset controller in probe stage")
  27c9445be86b1 ("i2c: imx-lpi2c: avoid accessing target registers on master-only controllers")

from the origin tree and commits:

  d2b83deba536d ("i2c: busses: drop redundant dev_err_probe() around irq helpers")
  c19f6f452664a ("i2c: imx-lpi2c: properly unwind resources on probe failure")
  90311787f483a ("i2c: imx-lpi2c: reset controller in probe stage")

from the i2c-rust tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

diff --combined drivers/i2c/busses/i2c-imx-lpi2c.c
index 1cfd7a4c82370,e1a4338bc51e9..0000000000000
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@@ -29,7 -29,6 +29,7 @@@
  
  #define DRIVER_NAME "imx-lpi2c"
  
 +#define LPI2C_VERID	0x00	/* i2c version ID */
  #define LPI2C_PARAM	0x04	/* i2c RX/TX FIFO size */
  #define LPI2C_MCR	0x10	/* i2c contrl register */
  #define LPI2C_MSR	0x14	/* i2c status register */
@@@ -137,9 -136,6 +137,9 @@@
  #define I2C_PM_LONG_TIMEOUT_MS	1000 /* Avoid dead lock caused by big clock prepare lock */
  #define I2C_DMA_THRESHOLD	8 /* bytes */
  
 +/* Bit 0 indicates the presence of the target feature */
 +#define VERID_FEATURE_TARGET_PRESENT	BIT(0)
 +
  enum lpi2c_imx_mode {
  	STANDARD,	/* 100+Kbps */
  	FAST,		/* 400+Kbps */
@@@ -198,7 -194,6 +198,7 @@@ struct lpi2c_imx_struct 
  	bool			can_use_dma;
  	struct lpi2c_imx_dma	*dma;
  	struct i2c_client	*target;
 +	bool			target_supported;
  	int			irq;
  	const struct imx_lpi2c_hwdata *hwdata;
  };
@@@ -1335,10 -1330,6 +1335,10 @@@ static int lpi2c_imx_register_target(st
  	struct lpi2c_imx_struct *lpi2c_imx = i2c_get_adapdata(client->adapter);
  	int ret;
  
 +	/* Reject target-mode registration on controllers that don't support it. */
 +	if (!lpi2c_imx->target_supported)
 +		return -EOPNOTSUPP;
 +
  	if (lpi2c_imx->target)
  		return -EBUSY;
  
@@@ -1555,23 -1546,13 +1555,13 @@@ static int lpi2c_imx_probe(struct platf
  	pm_runtime_enable(&pdev->dev);
  
  	/*
- 	 * Reset all internal controller registers to avoid effects of any
- 	 * state left over from a previous stage (e.g. the bootloader).
- 	 *
- 	 * The Master block (MCR) is present on every controller, so reset it
- 	 * unconditionally. VERID shows whether the target feature is supported.
- 	 * Do not touch the Target block (SCR) on a master-only controller to
- 	 * avoid an asynchronous SError.
+ 	 * Reset all internal controller registers of both Master and Target
+ 	 * to avoid effects of previous status.
  	 */
  	writel(MCR_RST, lpi2c_imx->base + LPI2C_MCR);
+ 	writel(SCR_RST, lpi2c_imx->base + LPI2C_SCR);
  	writel(0, lpi2c_imx->base + LPI2C_MCR);
- 
- 	lpi2c_imx->target_supported = !!(readl(lpi2c_imx->base + LPI2C_VERID) &
- 					 VERID_FEATURE_TARGET_PRESENT);
- 	if (lpi2c_imx->target_supported) {
- 		writel(SCR_RST, lpi2c_imx->base + LPI2C_SCR);
- 		writel(0, lpi2c_imx->base + LPI2C_SCR);
- 	}
+ 	writel(0, lpi2c_imx->base + LPI2C_SCR);
  
  	ret = devm_request_irq(&pdev->dev, lpi2c_imx->irq, lpi2c_imx_isr, IRQF_NO_SUSPEND,
  			       pdev->name, lpi2c_imx);

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Re: linux-next: manual merge of the i2c-rust tree with the origin tree

[Sasha Levin]

On Thu, Sep 10, 2026 at 03:21:28PM +0100, Mark Brown wrote:
> Today's linux-next merge of the i2c-rust tree got a conflict in:
>
>   drivers/i2c/busses/i2c-imx-lpi2c.c

Hi Mark,

The probe hunk of this resolution takes the i2c-rust side, which
reverts

27c9445be86b ("i2c: imx-lpi2c: avoid accessing target registers on master-only controllers")

SCR is written unconditionally again, so master-only controllers such
as i.MX8QM are back to the asynchronous SError at probe. target_supported
is also never set, so lpi2c_imx_register_target() always returns
-EOPNOTSUPP. It builds without warnings, and next-20261016 still has it.

That block should match mainline. The delta against next-20261016 is
below.

The conflict comes back on every merge because rust-i2c-next carries
older copies of mainline's lpi2c commits, for example

90311787f483 ("i2c: imx-lpi2c: reset controller in probe stage")

This is what llminus generated:

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
index dd5b8bcd05d04..7302464c371ae 100644
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -1553,13 +1553,23 @@ static int lpi2c_imx_probe(struct platform_device *pdev)
 	pm_runtime_enable(&pdev->dev);
 
 	/*
-	 * Reset all internal controller registers of both Master and Target
-	 * to avoid effects of previous status.
+	 * Reset all internal controller registers to avoid effects of any
+	 * state left over from a previous stage (e.g. the bootloader).
+	 *
+	 * The Master block (MCR) is present on every controller, so reset it
+	 * unconditionally. VERID shows whether the target feature is supported.
+	 * Do not touch the Target block (SCR) on a master-only controller to
+	 * avoid an asynchronous SError.
 	 */
 	writel(MCR_RST, lpi2c_imx->base + LPI2C_MCR);
-	writel(SCR_RST, lpi2c_imx->base + LPI2C_SCR);
 	writel(0, lpi2c_imx->base + LPI2C_MCR);
-	writel(0, lpi2c_imx->base + LPI2C_SCR);
+
+	lpi2c_imx->target_supported = !!(readl(lpi2c_imx->base + LPI2C_VERID) &
+					 VERID_FEATURE_TARGET_PRESENT);
+	if (lpi2c_imx->target_supported) {
+		writel(SCR_RST, lpi2c_imx->base + LPI2C_SCR);
+		writel(0, lpi2c_imx->base + LPI2C_SCR);
+	}
 
 	ret = devm_request_irq(&pdev->dev, lpi2c_imx->irq, lpi2c_imx_isr, IRQF_NO_SUSPEND,
 			       pdev->name, lpi2c_imx);
-- 
Thanks,
Sasha