Re: [PATCH v6 4/4] i2c: qcom-geni: Support multi-owner controllers in GPI mode

[Mukesh Savaliya <mukesh.savaliya@oss.qualcomm.com>]

Thanks Konrad for the review !

On 4/1/2026 3:51 PM, Konrad Dybcio wrote:
> On 3/31/26 1:47 PM, Mukesh Kumar Savaliya wrote:
>> Some platforms use a QUP-based I2C controller in a configuration where the
>> controller is shared with another system processor. In this setup the
>> operating system must not assume exclusive ownership of the controller or
>> its associated pins.
>>
>> Add support for enabling multi-owner operation when DeviceTree specifies
>> qcom,qup-multi-owner. When enabled, mark the underlying serial engine as
>> shared so the common GENI resource handling avoids selecting the "sleep"
>> pinctrl state, which could disrupt transfers initiated by the other
>> processor.
>>
>> For GPI mode transfers, request lock/unlock TRE sequencing from the GPI
>> driver by setting a single lock_action selector per message, emitting lock
>> before the first message and unlock after the last message (handling the
>> single-message case as well). This serializes access to the shared
>> controller without requiring message-position flags to be passed into the
>> DMA engine layer.
>>
>> Signed-off-by: Mukesh Kumar Savaliya <mukesh.savaliya@oss.qualcomm.com>
>> ---
> 
> [...]
> 
>> +	if (of_property_read_bool(pdev->dev.of_node, "qcom,qup-multi-owner")) {
>> +		/*
>> +		 * Multi-owner controller configuration: the controller may be
>> +		 * used by another system processor. Mark the SE as shared so
>> +		 * common GENI resource handling can avoid pin state changes
>> +		 * that would disrupt the other user.
>> +		 */
> 
> I don't find this comment very useful given we have kerneldoc for that
> property and the behavior you described impacts another file
> 
Makes sense, will remove this comment in the next patch upload.
> [...]
> 
>> +		if (gi2c->se.multi_owner)
>> +			dev_err_probe(dev, -EINVAL, "I2C sharing not supported in non GSI mode\n");
> 
> return dev_err_probe()
> 
Done, Thanks !
> Konrad
>