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

[Sudeep Holla]

On Mon, Feb 09, 2026 at 11:53:19AM +0100, Marek Vasut wrote:
> 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 ?
> 

As I had mentioned here[1], I am happy with it and I will pick it up for
v7.1 once I start collecting the patches after v7.0-rc1. It just came in after
I had sent my PR to SoC team for v7.0

-- 
Regards,
Sudeep

[1] https://lore.kernel.org/all/aW5jwtoYCFs-Pzpk@bogus/