[PATCH v4 2/2] firmware: arm_scmi: Implement arm,no-completion-irq property

[Marek Vasut]

On 1/19/26 5:57 PM, Cristian Marussi wrote:
> On Sat, Jan 17, 2026 at 02:02:29AM +0100, Marek Vasut wrote:
>> Implement new property arm,no-completion-irq, which sets all SCMI
>> operation into poll mode. This is meant to work around uncooperative
>> SCP implementations, which do not generate completion interrupts.
>> This applies to mbox/shmem based implementations.
>>
>> With this property set, such implementations which do not generate
>> interrupts can be interacted with, until they are fixed to generate
>> interrupts properly.
>>
>> Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
>> ---
>> Cc: Conor Dooley <conor+dt at kernel.org>
>> Cc: Cristian Marussi <cristian.marussi at arm.com>
>> Cc: Florian Fainelli <florian.fainelli at broadcom.com>
>> Cc: Krzysztof Kozlowski <krzk+dt at kernel.org>
>> Cc: Rob Herring <robh at kernel.org>
>> Cc: Sudeep Holla <sudeep.holla at arm.com>
>> Cc: arm-scmi at vger.kernel.org
>> Cc: devicetree at vger.kernel.org
>> Cc: linux-arm-kernel at lists.infradead.org
>> Cc: linux-renesas-soc at vger.kernel.org
>> ---
>> V2: Drop no IRQ handling from SMC transport and update commit message
>> V3: Rename property from arm,poll-transport to arm,no-completion-irq
>> V4: No change
>> ---
>>   drivers/firmware/arm_scmi/common.h | 4 ++++
>>   drivers/firmware/arm_scmi/driver.c | 4 ++++
>>   2 files changed, 8 insertions(+)
>>
>> diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
>> index 7c35c95fddbaf..7c9617d080a02 100644
>> --- a/drivers/firmware/arm_scmi/common.h
>> +++ b/drivers/firmware/arm_scmi/common.h
>> @@ -235,6 +235,9 @@ struct scmi_transport_ops {
>>    *		      to have an execution latency lesser-equal to the threshold
>>    *		      should be considered for atomic mode operation: such
>>    *		      decision is finally left up to the SCMI drivers.
>> + * @no_completion_irq: Flag to indicate that this transport has no completion
>> + *		       interrupt and has to be polled. This is similar to the
>> + *		       force_polling below, except this is set via DT property.
>>    * @force_polling: Flag to force this whole transport to use SCMI core polling
>>    *		   mechanism instead of completion interrupts even if available.
>>    * @sync_cmds_completed_on_ret: Flag to indicate that the transport assures
>> @@ -254,6 +257,7 @@ struct scmi_desc {
>>   	int max_msg;
>>   	int max_msg_size;
>>   	unsigned int atomic_threshold;
>> +	bool no_completion_irq;
>>   	const bool force_polling;
>>   	const bool sync_cmds_completed_on_ret;
>>   	const bool atomic_enabled;
>> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
>> index 3e76a3204ba4f..f167194f7cf67 100644
>> --- a/drivers/firmware/arm_scmi/driver.c
>> +++ b/drivers/firmware/arm_scmi/driver.c
>> @@ -2735,6 +2735,7 @@ static int scmi_chan_setup(struct scmi_info *info, struct device_node *of_node,
>>   	cinfo->is_p2a = !tx;
>>   	cinfo->rx_timeout_ms = info->desc->max_rx_timeout_ms;
>>   	cinfo->max_msg_size = info->desc->max_msg_size;
>> +	cinfo->no_completion_irq = info->desc->no_completion_irq;
>>   
>>   	/* Create a unique name for this transport device */
>>   	snprintf(name, 32, "__scmi_transport_device_%s_%02X",
>> @@ -3150,6 +3151,9 @@ static const struct scmi_desc *scmi_transport_setup(struct device *dev)
>>   	if (ret && ret != -EINVAL)
>>   		dev_err(dev, "Malformed arm,max-msg DT property.\n");
>>   
>> +	trans->desc.no_completion_irq = of_property_read_bool(dev->of_node,
>> +							      "arm,no-completion-irq");
>> +
>>   	dev_info(dev,
>>   		 "SCMI max-rx-timeout: %dms / max-msg-size: %dbytes / max-msg: %d\n",
>>   		 trans->desc.max_rx_timeout_ms, trans->desc.max_msg_size,
> 
> LGTM.
> 
> Reviewed-by: Cristian Marussi <cristian.marussi at arm.com>

Is there anything left to do with these patches, or can this now be 
picked up ?

Thank you.