[PATCH 0/6] i2c: provide and use i2c_adapter_dev()

[PATCH 0/6] i2c: provide and use i2c_adapter_dev()

[Bartosz Golaszewski]

It's been another year of discussing the object life-time problems at
conferences. I2C is one of the offenders and its problems are more
complex than those of some other subsystems. It seems the revocable[1]
API may make its way into the kernel this year but even with it in
place, I2C won't be able to use it as there's currently nothing to
*revoke*. The struct device is embedded within the i2c_adapter struct
whose lifetime is tied to the provider device being bound to its driver.

Fixing this won't be fast and easy but nothing's going to happen if we
don't start chipping away at it. The ultimate goal in order to be able
to use an SRCU-based solution (revocable or otherwise) is to convert the
embedded struct device in struct i2c_adapter into an __rcu pointer that
can be *revoked*. To that end we need to hide all dereferences of
adap->dev in drivers.

Other series address more generic problems - like printk helpers and
parent/of_node setting - but there are still some more specific
use-cases of drivers dereferencing the internal struct device of
i2c_adapters. We need to hide the fact that the device is embedded in
i2c_adapter before we can move it out so provide a helper that provides
the address of struct device without showing how it's stored and use it
in some drivers.

[1] https://lore.kernel.org/all/20251106152330.11733-1-tzungbi@kernel.org/

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
Bartosz Golaszewski (6):
      i2c: provide i2c_adapter_dev()
      i2c: piix4: use i2c_adapter_dev()
      i2c: amd-asf-plat: use i2c_adapter_dev()
      i2c: designware-amdisp: use i2c_adapter_dev()
      i2c: mv64xxx: use i2c_adapter_dev()
      i2c: viai2c-zhaoxin: use i2c_adapter_dev()

 drivers/i2c/busses/i2c-amd-asf-plat.c      | 4 ++--
 drivers/i2c/busses/i2c-designware-amdisp.c | 2 +-
 drivers/i2c/busses/i2c-mv64xxx.c           | 4 ++--
 drivers/i2c/busses/i2c-piix4.c             | 6 +++---
 drivers/i2c/busses/i2c-viai2c-zhaoxin.c    | 2 +-
 include/linux/i2c.h                        | 5 +++++
 6 files changed, 14 insertions(+), 9 deletions(-)
---
base-commit: 9448598b22c50c8a5bb77a9103e2d49f134c9578
change-id: 20251222-i2c-adapter-dev-wrapper-c882660190a2

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

[PATCH 1/6] i2c: provide i2c_adapter_dev()

[Bartosz Golaszewski]

Provide a wrapper around the dereferencing of i2c_adapter::dev. Once we
convert i2c drivers to using it, it will be possible to finally move the
embedded struct device into a separate, revocable structure protected by
SRCU.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 include/linux/i2c.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 20fd41b51d5c85ee1665395c07345faafd8e2fca..b5f4db9417aca2e058c8be19d57d693339b6f9b9 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -768,6 +768,11 @@ struct i2c_adapter {
 };
 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
 
+static inline struct device *i2c_adapter_dev(struct i2c_adapter *adap)
+{
+	return &adap->dev;
+}
+
 static inline void *i2c_get_adapdata(const struct i2c_adapter *adap)
 {
 	return dev_get_drvdata(&adap->dev);

-- 
2.47.3

[PATCH 2/6] i2c: piix4: use i2c_adapter_dev()

[Bartosz Golaszewski]

Use i2c_adapter_dev() where applicable in order to avoid direct
dereferencing of struct device embedded within struct i2c_adapter.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/i2c/busses/i2c-piix4.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index ac3bb550303fe5893822af50c385004c9292e695..4fe0c49284646a9f2910939c98b51ee6777e8b52 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -788,7 +788,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
 	u8 prev_port;
 	int retval;
 
-	retval = piix4_sb800_region_request(&adap->dev, &adapdata->mmio_cfg);
+	retval = piix4_sb800_region_request(i2c_adapter_dev(adap), &adapdata->mmio_cfg);
 	if (retval)
 		return retval;
 
@@ -859,7 +859,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
 		piix4_imc_wakeup();
 
 release:
-	piix4_sb800_region_release(&adap->dev, &adapdata->mmio_cfg);
+	piix4_sb800_region_release(i2c_adapter_dev(adap), &adapdata->mmio_cfg);
 	return retval;
 }
 
@@ -947,7 +947,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
 	adap->dev.parent = &dev->dev;
 
 	if (has_acpi_companion(&dev->dev)) {
-		acpi_preset_companion(&adap->dev,
+		acpi_preset_companion(i2c_adapter_dev(adap),
 				      ACPI_COMPANION(&dev->dev),
 				      hw_port_nr);
 	}

-- 
2.47.3

[PATCH 3/6] i2c: amd-asf-plat: use i2c_adapter_dev()

[Bartosz Golaszewski]

Use i2c_adapter_dev() where applicable in order to avoid direct
dereferencing of struct device embedded within struct i2c_adapter.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/i2c/busses/i2c-amd-asf-plat.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-amd-asf-plat.c b/drivers/i2c/busses/i2c-amd-asf-plat.c
index ca45f0f233210a3b03a16c4a240012bd524fefb0..271b1b24417d06cc87733268c3191aea16fa1d83 100644
--- a/drivers/i2c/busses/i2c-amd-asf-plat.c
+++ b/drivers/i2c/busses/i2c-amd-asf-plat.c
@@ -209,7 +209,7 @@ static int amd_asf_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	asf_data[0] = dev_msgs->len;
 	memcpy(asf_data + 1, dev_msgs[0].buf, dev_msgs->len);
 
-	ret = piix4_sb800_region_request(&adap->dev, &dev->mmio_cfg);
+	ret = piix4_sb800_region_request(i2c_adapter_dev(adap), &dev->mmio_cfg);
 	if (ret)
 		return ret;
 
@@ -224,7 +224,7 @@ static int amd_asf_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	ret = amd_asf_access(adap, msgs->addr, msgs[0].buf[0], asf_data);
 	piix4_sb800_port_sel(prev_port, &dev->mmio_cfg);
 	amd_asf_setup_target(dev);
-	piix4_sb800_region_release(&adap->dev, &dev->mmio_cfg);
+	piix4_sb800_region_release(i2c_adapter_dev(adap), &dev->mmio_cfg);
 	return ret;
 }
 

-- 
2.47.3

[PATCH 4/6] i2c: designware-amdisp: use i2c_adapter_dev()

[Bartosz Golaszewski]

Use i2c_adapter_dev() where applicable in order to avoid direct
dereferencing of struct device embedded within struct i2c_adapter.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/i2c/busses/i2c-designware-amdisp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-designware-amdisp.c b/drivers/i2c/busses/i2c-designware-amdisp.c
index 450793d5f83921ac9a8c6d00414890779da49c07..67772bccb71927e870c11fa88340caabcb07f264 100644
--- a/drivers/i2c/busses/i2c-designware-amdisp.c
+++ b/drivers/i2c/busses/i2c-designware-amdisp.c
@@ -64,7 +64,7 @@ static int amd_isp_dw_i2c_plat_probe(struct platform_device *pdev)
 	adap = &isp_i2c_dev->adapter;
 	adap->owner = THIS_MODULE;
 	scnprintf(adap->name, sizeof(adap->name), AMDISP_I2C_ADAP_NAME);
-	ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
+	ACPI_COMPANION_SET(i2c_adapter_dev(adap), ACPI_COMPANION(&pdev->dev));
 	adap->dev.of_node = pdev->dev.of_node;
 	/* use dynamically allocated adapter id */
 	adap->nr = -1;

-- 
2.47.3

[PATCH 5/6] i2c: mv64xxx: use i2c_adapter_dev()

[Bartosz Golaszewski]

Use i2c_adapter_dev() where applicable in order to avoid direct
dereferencing of struct device embedded within struct i2c_adapter.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/i2c/busses/i2c-mv64xxx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 1acba628e16c3bd1dbf82c777162870cbe3815ef..7892793d2a1cabf3376efcec1d031c3d764f7731 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -747,7 +747,7 @@ mv64xxx_i2c_xfer_core(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	struct mv64xxx_i2c_data *drv_data = i2c_get_adapdata(adap);
 	int rc, ret = num;
 
-	rc = pm_runtime_resume_and_get(&adap->dev);
+	rc = pm_runtime_resume_and_get(i2c_adapter_dev(adap));
 	if (rc)
 		return rc;
 
@@ -766,7 +766,7 @@ mv64xxx_i2c_xfer_core(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	drv_data->num_msgs = 0;
 	drv_data->msgs = NULL;
 
-	pm_runtime_put_autosuspend(&adap->dev);
+	pm_runtime_put_autosuspend(i2c_adapter_dev(adap));
 
 	return ret;
 }

-- 
2.47.3

[PATCH 6/6] i2c: viai2c-zhaoxin: use i2c_adapter_dev()

[Bartosz Golaszewski]

Use i2c_adapter_dev() where applicable in order to avoid direct
dereferencing of struct device embedded within struct i2c_adapter.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/i2c/busses/i2c-viai2c-zhaoxin.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-viai2c-zhaoxin.c b/drivers/i2c/busses/i2c-viai2c-zhaoxin.c
index 95dc64902b7cdb01beea04acf7bad8f20133d965..d68c1f38806deeb3f233315e717092e96473c887 100644
--- a/drivers/i2c/busses/i2c-viai2c-zhaoxin.c
+++ b/drivers/i2c/busses/i2c-viai2c-zhaoxin.c
@@ -323,7 +323,7 @@ static int zxi2c_probe(struct platform_device *pdev)
 	adap->algo = &zxi2c_algorithm;
 	adap->quirks = &zxi2c_quirks;
 	adap->dev.parent = &pdev->dev;
-	ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
+	ACPI_COMPANION_SET(i2c_adapter_dev(adap), ACPI_COMPANION(&pdev->dev));
 	snprintf(adap->name, sizeof(adap->name), "zhaoxin-%s-%s",
 		 dev_name(pdev->dev.parent), dev_name(i2c->dev));
 	i2c_set_adapdata(adap, i2c);

-- 
2.47.3

Re: [PATCH 3/6] i2c: amd-asf-plat: use i2c_adapter_dev()

[Shyam Sundar S K]

On 12/23/2025 15:38, Bartosz Golaszewski wrote:
> Use i2c_adapter_dev() where applicable in order to avoid direct
> dereferencing of struct device embedded within struct i2c_adapter.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>

Thanks,
Shyam

> ---
>  drivers/i2c/busses/i2c-amd-asf-plat.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-amd-asf-plat.c b/drivers/i2c/busses/i2c-amd-asf-plat.c
> index ca45f0f233210a3b03a16c4a240012bd524fefb0..271b1b24417d06cc87733268c3191aea16fa1d83 100644
> --- a/drivers/i2c/busses/i2c-amd-asf-plat.c
> +++ b/drivers/i2c/busses/i2c-amd-asf-plat.c
> @@ -209,7 +209,7 @@ static int amd_asf_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  	asf_data[0] = dev_msgs->len;
>  	memcpy(asf_data + 1, dev_msgs[0].buf, dev_msgs->len);
>  
> -	ret = piix4_sb800_region_request(&adap->dev, &dev->mmio_cfg);
> +	ret = piix4_sb800_region_request(i2c_adapter_dev(adap), &dev->mmio_cfg);
>  	if (ret)
>  		return ret;
>  
> @@ -224,7 +224,7 @@ static int amd_asf_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  	ret = amd_asf_access(adap, msgs->addr, msgs[0].buf[0], asf_data);
>  	piix4_sb800_port_sel(prev_port, &dev->mmio_cfg);
>  	amd_asf_setup_target(dev);
> -	piix4_sb800_region_release(&adap->dev, &dev->mmio_cfg);
> +	piix4_sb800_region_release(i2c_adapter_dev(adap), &dev->mmio_cfg);
>  	return ret;
>  }
>  
> 

Re: [PATCH 4/6] i2c: designware-amdisp: use i2c_adapter_dev()

[Andy Shevchenko]

On Tue, Dec 23, 2025 at 11:08:21AM +0100, Bartosz Golaszewski wrote:
> Use i2c_adapter_dev() where applicable in order to avoid direct
> dereferencing of struct device embedded within struct i2c_adapter.

...

> -	ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
> +	ACPI_COMPANION_SET(i2c_adapter_dev(adap), ACPI_COMPANION(&pdev->dev));
>  	adap->dev.of_node = pdev->dev.of_node;

Why not just replace these with i2c_dev_set_node()?


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 4/6] i2c: designware-amdisp: use i2c_adapter_dev()

[Andy Shevchenko]

On Sat, Dec 27, 2025 at 04:29:43PM +0200, Andy Shevchenko wrote:
> On Tue, Dec 23, 2025 at 11:08:21AM +0100, Bartosz Golaszewski wrote:

...

> > -	ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
> > +	ACPI_COMPANION_SET(i2c_adapter_dev(adap), ACPI_COMPANION(&pdev->dev));
> >  	adap->dev.of_node = pdev->dev.of_node;
> 
> Why not just replace these with i2c_dev_set_node()?

Oh, I meant the i2c_adapter_set_node() that you just introduced in the previous
series. Effectively this makes a patch of that series.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 6/6] i2c: viai2c-zhaoxin: use i2c_adapter_dev()

[Andy Shevchenko]

On Tue, Dec 23, 2025 at 11:08:23AM +0100, Bartosz Golaszewski wrote:
> Use i2c_adapter_dev() where applicable in order to avoid direct
> dereferencing of struct device embedded within struct i2c_adapter.

...

> -	ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
> +	ACPI_COMPANION_SET(i2c_adapter_dev(adap), ACPI_COMPANION(&pdev->dev));

Same comment, use i2c_adapter_set_node().

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 5/6] i2c: mv64xxx: use i2c_adapter_dev()

[Gregory CLEMENT]

Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com> writes:

> Use i2c_adapter_dev() where applicable in order to avoid direct
> dereferencing of struct device embedded within struct i2c_adapter.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com>

Thanks,

Gregory
> ---
>  drivers/i2c/busses/i2c-mv64xxx.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
> index 1acba628e16c3bd1dbf82c777162870cbe3815ef..7892793d2a1cabf3376efcec1d031c3d764f7731 100644
> --- a/drivers/i2c/busses/i2c-mv64xxx.c
> +++ b/drivers/i2c/busses/i2c-mv64xxx.c
> @@ -747,7 +747,7 @@ mv64xxx_i2c_xfer_core(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  	struct mv64xxx_i2c_data *drv_data = i2c_get_adapdata(adap);
>  	int rc, ret = num;
>  
> -	rc = pm_runtime_resume_and_get(&adap->dev);
> +	rc = pm_runtime_resume_and_get(i2c_adapter_dev(adap));
>  	if (rc)
>  		return rc;
>  
> @@ -766,7 +766,7 @@ mv64xxx_i2c_xfer_core(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  	drv_data->num_msgs = 0;
>  	drv_data->msgs = NULL;
>  
> -	pm_runtime_put_autosuspend(&adap->dev);
> +	pm_runtime_put_autosuspend(i2c_adapter_dev(adap));
>  
>  	return ret;
>  }
>
> -- 
> 2.47.3
>

-- 
Grégory CLEMENT, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH 4/6] i2c: designware-amdisp: use i2c_adapter_dev()

[Nirujogi, Pratap]

On 12/23/2025 5:08 AM, Bartosz Golaszewski wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> Use i2c_adapter_dev() where applicable in order to avoid direct
> dereferencing of struct device embedded within struct i2c_adapter.
>
> Signed-off-by: Bartosz Golaszewski<bartosz.golaszewski@oss.qualcomm.com>

Acked-by: Pratap Nirujogi<pratap.nirujogi@amd.com>

(I'm assuming Andy's suggestion to use i2c_adapter_set_node() will be covered in the other patch series)

Thanks,
Pratap

> ---
>   drivers/i2c/busses/i2c-designware-amdisp.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-amdisp.c b/drivers/i2c/busses/i2c-designware-amdisp.c
> index 450793d5f83921ac9a8c6d00414890779da49c07..67772bccb71927e870c11fa88340caabcb07f264 100644
> --- a/drivers/i2c/busses/i2c-designware-amdisp.c
> +++ b/drivers/i2c/busses/i2c-designware-amdisp.c
> @@ -64,7 +64,7 @@ static int amd_isp_dw_i2c_plat_probe(struct platform_device *pdev)
>          adap = &isp_i2c_dev->adapter;
>          adap->owner = THIS_MODULE;
>          scnprintf(adap->name, sizeof(adap->name), AMDISP_I2C_ADAP_NAME);
> -       ACPI_COMPANION_SET(&adap->dev, ACPI_COMPANION(&pdev->dev));
> +       ACPI_COMPANION_SET(i2c_adapter_dev(adap), ACPI_COMPANION(&pdev->dev));
>          adap->dev.of_node = pdev->dev.of_node;
>          /* use dynamically allocated adapter id */
>          adap->nr = -1;
>
> --
> 2.47.3
>

Re: [PATCH 4/6] i2c: designware-amdisp: use i2c_adapter_dev()

[Andy Shevchenko]

On Mon, Jan 05, 2026 at 02:26:06PM -0500, Nirujogi, Pratap wrote:
> On 12/23/2025 5:08 AM, Bartosz Golaszewski wrote:

> > Use i2c_adapter_dev() where applicable in order to avoid direct
> > dereferencing of struct device embedded within struct i2c_adapter.
> > 
> > Signed-off-by: Bartosz Golaszewski<bartosz.golaszewski@oss.qualcomm.com>
> 
> Acked-by: Pratap Nirujogi<pratap.nirujogi@amd.com>
> 
> (I'm assuming Andy's suggestion to use i2c_adapter_set_node() will be covered
> in the other patch series)

With that done, this patch won't be needed at all.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 2/6] i2c: piix4: use i2c_adapter_dev()

[Jean Delvare]

Hi Bartosz,

On Tue, 23 Dec 2025 11:08:19 +0100, Bartosz Golaszewski wrote:
> Use i2c_adapter_dev() where applicable in order to avoid direct
> dereferencing of struct device embedded within struct i2c_adapter.

I will confess that I don't know what is wrong with the current way of
embedding struct device in a more specific device structure. I seem to
recall it was fairly standard to do things this way back when we
implemented this in the i2c subsystem. But I will trust you that this
change is needed now.

> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
> ---
>  drivers/i2c/busses/i2c-piix4.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index ac3bb550303fe5893822af50c385004c9292e695..4fe0c49284646a9f2910939c98b51ee6777e8b52 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -788,7 +788,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>  	u8 prev_port;
>  	int retval;
>  
> -	retval = piix4_sb800_region_request(&adap->dev, &adapdata->mmio_cfg);
> +	retval = piix4_sb800_region_request(i2c_adapter_dev(adap), &adapdata->mmio_cfg);
>  	if (retval)
>  		return retval;
>  
> @@ -859,7 +859,7 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
>  		piix4_imc_wakeup();
>  
>  release:
> -	piix4_sb800_region_release(&adap->dev, &adapdata->mmio_cfg);
> +	piix4_sb800_region_release(i2c_adapter_dev(adap), &adapdata->mmio_cfg);
>  	return retval;
>  }
>  
> @@ -947,7 +947,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
>  	adap->dev.parent = &dev->dev;
>  
>  	if (has_acpi_companion(&dev->dev)) {
> -		acpi_preset_companion(&adap->dev,
> +		acpi_preset_companion(i2c_adapter_dev(adap),
>  				      ACPI_COMPANION(&dev->dev),
>  				      hw_port_nr);
>  	}
> 

Acked-by: Jean Delvare <jdelvare@suse.de>

I see that you left one occurrence:

	adap->dev.parent = &dev->dev;

I presume we'll need a wrapper for this construct as well?

Thanks,
-- 
Jean Delvare
SUSE L3 Support

Re: [PATCH 2/6] i2c: piix4: use i2c_adapter_dev()

[Wolfram Sang]

Hi Jean,

> > Use i2c_adapter_dev() where applicable in order to avoid direct
> > dereferencing of struct device embedded within struct i2c_adapter.
> 
> I will confess that I don't know what is wrong with the current way of
> embedding struct device in a more specific device structure. I seem to
> recall it was fairly standard to do things this way back when we
> implemented this in the i2c subsystem. But I will trust you that this
> change is needed now.

I guess more people will wonder about the upcoming I2C core changes, so
I wrote a bit of explanation:

https://lore.kernel.org/all/aWYYZEPX-_1GfQtL@ninjato/

Happy hacking,

   Wolfram