[PATCH 0/4] i2c: Support i2c_register_spd() on multiplexed bus segments

[PATCH 0/4] i2c: Support i2c_register_spd() on multiplexed bus segments

[Heiner Kallweit]

i801 is the last bus driver supporting I2C_CLASS_SPD. It's used for
device probing on muxed bus segments. Only known use case so far is
systems with more than 8 memory modules (with thermal sensor) on
muxed smbus segments.
As discussed with Jean, to be able to remove I2C_CLASS_SPD completely
the following has to be done:

1. Extend i2c_register_spd() for use on muxed bus segments
2. Enable explicit instantiation of thermal sensors on memory modules
3. Extend i801 to call i2c_register_spd() on muxed bus segments

Step 2 has been accomplished:
caba40ec3531 ("eeprom: at24: Probe for DDR3 thermal sensor in the SPD case")
393bd1000f81 ("eeprom: ee1004: add support for temperature sensor")

Patch 1 does step 1
Patches 2 and 3 provide the basis for patch 4
Patch 4 does step 3

Note: i801 creates the mux platform device, loading and probing of the
mux driver may be asynchronous. Therefore we can't call i2c_register_spd()
for the muxed segments from i801. Instead we have to add a flag to the
platform data, so that the mux driver knows it's supposed to call
i2c_register_spd().

This series replaces the earlier RFC series.

Heiner Kallweit (4):
  i2c: smbus: Prepare i2c_register_spd for usage on muxed segments
  i2c: mux: add basic support for calling i2c_register_spd on muxed bus
    segments
  i2c: mux: gpio: Allow to call i2c_register_spd on a muxed segment
  i2c: i801: Call i2c_register_spd() on muxed bus segments

 drivers/i2c/busses/i2c-i801.c              |  1 +
 drivers/i2c/i2c-mux.c                      |  4 ++++
 drivers/i2c/i2c-smbus.c                    | 19 ++++++++++++-------
 drivers/i2c/muxes/i2c-mux-gpio.c           |  1 +
 include/linux/i2c-mux.h                    |  1 +
 include/linux/platform_data/i2c-mux-gpio.h |  2 ++
 6 files changed, 21 insertions(+), 7 deletions(-)

-- 
2.43.0

[PATCH 1/4] i2c: smbus: Prepare i2c_register_spd for usage on muxed segments

[Heiner Kallweit]

If this is an adapter on a muxed bus segment, assume that each segment
is connected to a subset of the (> 8) overall memory slots. In this
case let's probe the maximum of 8 slots, however stop if the number
of overall populated slots is reached.

If we're not on a muxed segment and the total number of slots is > 8,
report an error, because then not all SPD eeproms can be addressed.
Presumably the bus is muxed, but the mux config is missing.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/i2c/i2c-smbus.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 74807c6db..e94714d5a 100644
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -351,13 +351,18 @@ void i2c_register_spd(struct i2c_adapter *adap)
 	if (!dimm_count)
 		return;
 
-	dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
-		 dimm_count, slot_count);
-
-	if (slot_count > 8) {
-		dev_warn(&adap->dev,
-			 "Systems with more than 8 memory slots not supported yet, not instantiating SPD\n");
-		return;
+	/* Check whether we're a child adapter on a muxed segment */
+	if (i2c_parent_is_i2c_adapter(adap)) {
+		if (slot_count > 8)
+			slot_count = 8;
+	} else {
+		dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
+			 dimm_count, slot_count);
+		if (slot_count > 8) {
+			dev_err(&adap->dev,
+				"More than 8 memory slots on a single bus, mux config missing?\n");
+			return;
+		}
 	}
 
 	/*
-- 
2.43.0

Re: [PATCH 1/4] i2c: smbus: Prepare i2c_register_spd for usage on muxed segments

[Peter Rosin]

Hi!

2024-01-10 at 21:13, Heiner Kallweit wrote:
> If this is an adapter on a muxed bus segment, assume that each segment
> is connected to a subset of the (> 8) overall memory slots. In this
> case let's probe the maximum of 8 slots, however stop if the number
> of overall populated slots is reached.
> 
> If we're not on a muxed segment and the total number of slots is > 8,
> report an error, because then not all SPD eeproms can be addressed.
> Presumably the bus is muxed, but the mux config is missing.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
>  drivers/i2c/i2c-smbus.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
> index 74807c6db..e94714d5a 100644
> --- a/drivers/i2c/i2c-smbus.c
> +++ b/drivers/i2c/i2c-smbus.c
> @@ -351,13 +351,18 @@ void i2c_register_spd(struct i2c_adapter *adap)
>  	if (!dimm_count)
>  		return;
>  
> -	dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
> -		 dimm_count, slot_count);
> -
> -	if (slot_count > 8) {
> -		dev_warn(&adap->dev,
> -			 "Systems with more than 8 memory slots not supported yet, not instantiating SPD\n");
> -		return;
> +	/* Check whether we're a child adapter on a muxed segment */
> +	if (i2c_parent_is_i2c_adapter(adap)) {
> +		if (slot_count > 8)
> +			slot_count = 8;'

The comment "Only works on systems with 1 to 8 memory slots" above
i2c_register_spd() is now incorrect and needs adjusting.

> +	} else {
> +		dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
> +			 dimm_count, slot_count);
> +		if (slot_count > 8) {
> +			dev_err(&adap->dev,
> +				"More than 8 memory slots on a single bus, mux config missing?\n");
> +			return;
> +		}
>  	}
>  
>  	/*

The loop below this hunk is limited by dimm_count, but it is checked
separately for each muxed segment. It is therefore now possible to
instantiate a total number of slots larger than the dimm_count.
That was not possible before. I don't know if that's a problem, but
the check have been (silently) relaxed.

Cheers,
Peter

Re: [PATCH 1/4] i2c: smbus: Prepare i2c_register_spd for usage on muxed segments

[Heiner Kallweit]

On 11.01.2024 00:00, Peter Rosin wrote:
> Hi!
> 
> 2024-01-10 at 21:13, Heiner Kallweit wrote:
>> If this is an adapter on a muxed bus segment, assume that each segment
>> is connected to a subset of the (> 8) overall memory slots. In this
>> case let's probe the maximum of 8 slots, however stop if the number
>> of overall populated slots is reached.
>>
>> If we're not on a muxed segment and the total number of slots is > 8,
>> report an error, because then not all SPD eeproms can be addressed.
>> Presumably the bus is muxed, but the mux config is missing.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>>  drivers/i2c/i2c-smbus.c | 19 ++++++++++++-------
>>  1 file changed, 12 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
>> index 74807c6db..e94714d5a 100644
>> --- a/drivers/i2c/i2c-smbus.c
>> +++ b/drivers/i2c/i2c-smbus.c
>> @@ -351,13 +351,18 @@ void i2c_register_spd(struct i2c_adapter *adap)
>>  	if (!dimm_count)
>>  		return;
>>  
>> -	dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
>> -		 dimm_count, slot_count);
>> -
>> -	if (slot_count > 8) {
>> -		dev_warn(&adap->dev,
>> -			 "Systems with more than 8 memory slots not supported yet, not instantiating SPD\n");
>> -		return;
>> +	/* Check whether we're a child adapter on a muxed segment */
>> +	if (i2c_parent_is_i2c_adapter(adap)) {
>> +		if (slot_count > 8)
>> +			slot_count = 8;'
> 
> The comment "Only works on systems with 1 to 8 memory slots" above
> i2c_register_spd() is now incorrect and needs adjusting.
> 
Right, this comment can be removed.
I'll wait for more feedback on the series before submitting a v2.

>> +	} else {
>> +		dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
>> +			 dimm_count, slot_count);
>> +		if (slot_count > 8) {
>> +			dev_err(&adap->dev,
>> +				"More than 8 memory slots on a single bus, mux config missing?\n");
>> +			return;
>> +		}
>>  	}
>>  
>>  	/*
> 
> The loop below this hunk is limited by dimm_count, but it is checked
> separately for each muxed segment. It is therefore now possible to
> instantiate a total number of slots larger than the dimm_count.
> That was not possible before. I don't know if that's a problem, but
> the check have been (silently) relaxed.
> 
That's intentional. Keeping the current logic would have required to
add some kind of counter at the parent level, keeping track of how many
memory modules were instantiated per muxed segment.
For the sake of simplicity this was omitted. Instead we may probe more
slots than needed, however only impact should be that i2c_register_spd()
may take a little bit longer on affected systems.

> Cheers,
> Peter

Heiner

[PATCH 2/4] i2c: mux: add basic support for calling i2c_register_spd on muxed bus segments

[Heiner Kallweit]

This extension allows mux drivers to instruct i2c_mux_add_adapter to
call i2c_register_spd. First user of this feature will be gpio mux.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/i2c/i2c-mux.c   | 4 ++++
 include/linux/i2c-mux.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 57ff09f18..ada9c764f 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -22,6 +22,7 @@
 #include <linux/acpi.h>
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
+#include <linux/i2c-smbus.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -429,6 +430,9 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
 		 i2c_adapter_id(&priv->adap));
 
+	if (muxc->register_spd)
+		i2c_register_spd(&priv->adap);
+
 	muxc->adapter[muxc->num_adapters++] = &priv->adap;
 	return 0;
 
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
index 98ef73b7c..ec51d9bc4 100644
--- a/include/linux/i2c-mux.h
+++ b/include/linux/i2c-mux.h
@@ -21,6 +21,7 @@ struct i2c_mux_core {
 	unsigned int mux_locked:1;
 	unsigned int arbitrator:1;
 	unsigned int gate:1;
+	unsigned int register_spd:1;
 
 	void *priv;
 
-- 
2.43.0

Re: [PATCH 2/4] i2c: mux: add basic support for calling i2c_register_spd on muxed bus segments

[kernel test robot]

Hi Heiner,

kernel test robot noticed the following build errors:

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on next-20240111]
[cannot apply to linus/master v6.7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Heiner-Kallweit/i2c-smbus-Prepare-i2c_register_spd-for-usage-on-muxed-segments/20240111-042152
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
patch link:    https://lore.kernel.org/r/53e5c71a-d954-4211-91a1-de067451d532%40gmail.com
patch subject: [PATCH 2/4] i2c: mux: add basic support for calling i2c_register_spd on muxed bus segments
config: i386-randconfig-053-20240111 (https://download.01.org/0day-ci/archive/20240111/202401112333.GUpSFOuc-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240111/202401112333.GUpSFOuc-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401112333.GUpSFOuc-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: drivers/i2c/i2c-mux.o: in function `i2c_mux_add_adapter':
>> drivers/i2c/i2c-mux.c:434: undefined reference to `i2c_register_spd'


vim +434 drivers/i2c/i2c-mux.c

   283	
   284	int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
   285				u32 force_nr, u32 chan_id,
   286				unsigned int class)
   287	{
   288		struct i2c_adapter *parent = muxc->parent;
   289		struct i2c_mux_priv *priv;
   290		char symlink_name[20];
   291		int ret;
   292	
   293		if (muxc->num_adapters >= muxc->max_adapters) {
   294			dev_err(muxc->dev, "No room for more i2c-mux adapters\n");
   295			return -EINVAL;
   296		}
   297	
   298		priv = kzalloc(sizeof(*priv), GFP_KERNEL);
   299		if (!priv)
   300			return -ENOMEM;
   301	
   302		/* Set up private adapter data */
   303		priv->muxc = muxc;
   304		priv->chan_id = chan_id;
   305	
   306		/* Need to do algo dynamically because we don't know ahead
   307		 * of time what sort of physical adapter we'll be dealing with.
   308		 */
   309		if (parent->algo->master_xfer) {
   310			if (muxc->mux_locked)
   311				priv->algo.master_xfer = i2c_mux_master_xfer;
   312			else
   313				priv->algo.master_xfer = __i2c_mux_master_xfer;
   314		}
   315		if (parent->algo->master_xfer_atomic)
   316			priv->algo.master_xfer_atomic = priv->algo.master_xfer;
   317	
   318		if (parent->algo->smbus_xfer) {
   319			if (muxc->mux_locked)
   320				priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
   321			else
   322				priv->algo.smbus_xfer = __i2c_mux_smbus_xfer;
   323		}
   324		if (parent->algo->smbus_xfer_atomic)
   325			priv->algo.smbus_xfer_atomic = priv->algo.smbus_xfer;
   326	
   327		priv->algo.functionality = i2c_mux_functionality;
   328	
   329		/* Now fill out new adapter structure */
   330		snprintf(priv->adap.name, sizeof(priv->adap.name),
   331			 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
   332		priv->adap.owner = THIS_MODULE;
   333		priv->adap.algo = &priv->algo;
   334		priv->adap.algo_data = priv;
   335		priv->adap.dev.parent = &parent->dev;
   336		priv->adap.retries = parent->retries;
   337		priv->adap.timeout = parent->timeout;
   338		priv->adap.quirks = parent->quirks;
   339		if (muxc->mux_locked)
   340			priv->adap.lock_ops = &i2c_mux_lock_ops;
   341		else
   342			priv->adap.lock_ops = &i2c_parent_lock_ops;
   343	
   344		/* Sanity check on class */
   345		if (i2c_mux_parent_classes(parent) & class & ~I2C_CLASS_DEPRECATED)
   346			dev_err(&parent->dev,
   347				"Segment %d behind mux can't share classes with ancestors\n",
   348				chan_id);
   349		else
   350			priv->adap.class = class;
   351	
   352		/*
   353		 * Try to populate the mux adapter's of_node, expands to
   354		 * nothing if !CONFIG_OF.
   355		 */
   356		if (muxc->dev->of_node) {
   357			struct device_node *dev_node = muxc->dev->of_node;
   358			struct device_node *mux_node, *child = NULL;
   359			u32 reg;
   360	
   361			if (muxc->arbitrator)
   362				mux_node = of_get_child_by_name(dev_node, "i2c-arb");
   363			else if (muxc->gate)
   364				mux_node = of_get_child_by_name(dev_node, "i2c-gate");
   365			else
   366				mux_node = of_get_child_by_name(dev_node, "i2c-mux");
   367	
   368			if (mux_node) {
   369				/* A "reg" property indicates an old-style DT entry */
   370				if (!of_property_read_u32(mux_node, "reg", &reg)) {
   371					of_node_put(mux_node);
   372					mux_node = NULL;
   373				}
   374			}
   375	
   376			if (!mux_node)
   377				mux_node = of_node_get(dev_node);
   378			else if (muxc->arbitrator || muxc->gate)
   379				child = of_node_get(mux_node);
   380	
   381			if (!child) {
   382				for_each_child_of_node(mux_node, child) {
   383					ret = of_property_read_u32(child, "reg", &reg);
   384					if (ret)
   385						continue;
   386					if (chan_id == reg)
   387						break;
   388				}
   389			}
   390	
   391			priv->adap.dev.of_node = child;
   392			of_node_put(mux_node);
   393		}
   394	
   395		/*
   396		 * Associate the mux channel with an ACPI node.
   397		 */
   398		if (has_acpi_companion(muxc->dev))
   399			acpi_preset_companion(&priv->adap.dev,
   400					      ACPI_COMPANION(muxc->dev),
   401					      chan_id);
   402	
   403		if (force_nr) {
   404			priv->adap.nr = force_nr;
   405			ret = i2c_add_numbered_adapter(&priv->adap);
   406			if (ret < 0) {
   407				dev_err(&parent->dev,
   408					"failed to add mux-adapter %u as bus %u (error=%d)\n",
   409					chan_id, force_nr, ret);
   410				goto err_free_priv;
   411			}
   412		} else {
   413			ret = i2c_add_adapter(&priv->adap);
   414			if (ret < 0) {
   415				dev_err(&parent->dev,
   416					"failed to add mux-adapter %u (error=%d)\n",
   417					chan_id, ret);
   418				goto err_free_priv;
   419			}
   420		}
   421	
   422		WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj,
   423				       "mux_device"),
   424		     "can't create symlink to mux device\n");
   425	
   426		snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
   427		WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj,
   428				       symlink_name),
   429		     "can't create symlink to channel %u\n", chan_id);
   430		dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
   431			 i2c_adapter_id(&priv->adap));
   432	
   433		if (muxc->register_spd)
 > 434			i2c_register_spd(&priv->adap);
   435	
   436		muxc->adapter[muxc->num_adapters++] = &priv->adap;
   437		return 0;
   438	
   439	err_free_priv:
   440		kfree(priv);
   441		return ret;
   442	}
   443	EXPORT_SYMBOL_GPL(i2c_mux_add_adapter);
   444	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 2/4] i2c: mux: add basic support for calling i2c_register_spd on muxed bus segments

[kernel test robot]

Hi Heiner,

kernel test robot noticed the following build errors:

[auto build test ERROR on wsa/i2c/for-next]
[also build test ERROR on next-20240112]
[cannot apply to linus/master v6.7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Heiner-Kallweit/i2c-smbus-Prepare-i2c_register_spd-for-usage-on-muxed-segments/20240111-042152
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
patch link:    https://lore.kernel.org/r/53e5c71a-d954-4211-91a1-de067451d532%40gmail.com
patch subject: [PATCH 2/4] i2c: mux: add basic support for calling i2c_register_spd on muxed bus segments
config: loongarch-randconfig-001-20240111 (https://download.01.org/0day-ci/archive/20240113/202401131601.Qe16pupf-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240113/202401131601.Qe16pupf-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401131601.Qe16pupf-lkp@intel.com/

All errors (new ones prefixed by >>):

   loongarch64-linux-ld: drivers/i2c/i2c-mux.o: in function `.L155':
>> i2c-mux.c:(.text+0xc84): undefined reference to `i2c_register_spd'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH 3/4] i2c: mux: gpio: Allow to call i2c_register_spd on a muxed segment

[Heiner Kallweit]

Allow the gpio-based multiplexer to call i2c_register_spd on
muxed segments. First user will be i801.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/i2c/muxes/i2c-mux-gpio.c           | 1 +
 include/linux/platform_data/i2c-mux-gpio.h | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index 6b979a0a6..c841407c7 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -161,6 +161,7 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
 	}
 	mux->gpios = muxc->priv;
 	muxc->priv = mux;
+	muxc->register_spd = mux->data.register_spd;
 
 	platform_set_drvdata(pdev, muxc);
 
diff --git a/include/linux/platform_data/i2c-mux-gpio.h b/include/linux/platform_data/i2c-mux-gpio.h
index 5e4c2c272..cbeb74f92 100644
--- a/include/linux/platform_data/i2c-mux-gpio.h
+++ b/include/linux/platform_data/i2c-mux-gpio.h
@@ -20,6 +20,7 @@
  * @n_values: Number of multiplexer positions (busses to instantiate)
  * @classes: Optional I2C auto-detection classes
  * @idle: Bitmask to write to MUX when idle or GPIO_I2CMUX_NO_IDLE if not used
+ * @register_spd: call i2c_register_spd for the child adapters on muxed segments
  */
 struct i2c_mux_gpio_platform_data {
 	int parent;
@@ -28,6 +29,7 @@ struct i2c_mux_gpio_platform_data {
 	int n_values;
 	const unsigned *classes;
 	unsigned idle;
+	unsigned int register_spd:1;
 };
 
 #endif /* _LINUX_I2C_MUX_GPIO_H */
-- 
2.43.0

[PATCH 4/4] i2c: i801: Call i2c_register_spd() on muxed bus segments

[Heiner Kallweit]

Instruct child adapters to call i2c_register_spd() for each muxed
bus segment.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/i2c/busses/i2c-i801.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 3932e8d96..15c93ec5b 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -1404,6 +1404,7 @@ static void i801_add_mux(struct i801_priv *priv)
 	gpio_data.n_values = mux_config->n_values;
 	gpio_data.classes = mux_config->classes;
 	gpio_data.idle = I2C_MUX_GPIO_NO_IDLE;
+	gpio_data.register_spd = 1;
 
 	/* Register GPIO descriptor lookup table */
 	lookup = devm_kzalloc(dev,
-- 
2.43.0