diff mbox series

[v1,1/4] bus: mhi: core: Add support for processing priority of event ring

Message ID 1623965435-30224-2-git-send-email-bbhatt@codeaurora.org (mailing list archive)
State Not Applicable, archived
Headers show
Series MHI event ring priority updates | expand

Commit Message

Bhaumik Bhatt June 17, 2021, 9:30 p.m. UTC 
From: Hemant Kumar <hemantk@codeaurora.org>

Event ring priorities are currently set to 1 and are unused.
Default processing priority for event rings is set to regular
tasklet. Controllers can choose to use high priority tasklet
scheduling for certain event rings critical for processing such
as ones transporting control information if they wish to avoid
with system scheduling delays for those packets. In order to
support these use cases, allow controllers to set event ring
priority to high. This patch only adds support and does not
enable usage of these priorities.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
---
 drivers/bus/mhi/core/internal.h |  2 +-
 drivers/bus/mhi/core/main.c     | 19 ++++++++++++++++---
 include/linux/mhi.h             | 14 ++++++++++++--
 3 files changed, 29 insertions(+), 6 deletions(-)

Comments

Manivannan Sadhasivam June 18, 2021, 7:03 a.m. UTC | #1 
On Thu, Jun 17, 2021 at 02:30:32PM -0700, Bhaumik Bhatt wrote:
> From: Hemant Kumar <hemantk@codeaurora.org>
> 
> Event ring priorities are currently set to 1 and are unused.
> Default processing priority for event rings is set to regular
> tasklet. Controllers can choose to use high priority tasklet
> scheduling for certain event rings critical for processing such
> as ones transporting control information if they wish to avoid
> with system scheduling delays for those packets. In order to
> support these use cases, allow controllers to set event ring
> priority to high. This patch only adds support and does not
> enable usage of these priorities.
> 
> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> ---
>  drivers/bus/mhi/core/internal.h |  2 +-
>  drivers/bus/mhi/core/main.c     | 19 ++++++++++++++++---
>  include/linux/mhi.h             | 14 ++++++++++++--
>  3 files changed, 29 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
> index 672052f..666e102 100644
> --- a/drivers/bus/mhi/core/internal.h
> +++ b/drivers/bus/mhi/core/internal.h
> @@ -535,7 +535,7 @@ struct mhi_event {
>  	u32 intmod;
>  	u32 irq;
>  	int chan; /* this event ring is dedicated to a channel (optional) */
> -	u32 priority;
> +	enum mhi_er_priority priority;

Instead of using enum for priorities, can we just make use of the
existing "priority" field? Since the existing controllers set it to "1",
can we use "0" as the high priority?

This way we don't need to change the controller drivers.

>  	enum mhi_er_data_type data_type;
>  	struct mhi_ring ring;
>  	struct db_cfg db_cfg;
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 8ac73f9..bfc9776 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -425,10 +425,11 @@ void mhi_create_devices(struct mhi_controller *mhi_cntrl)
>  	}
>  }
>  
> -irqreturn_t mhi_irq_handler(int irq_number, void *dev)
> +irqreturn_t mhi_irq_handler(int irq_number, void *priv)
>  {
> -	struct mhi_event *mhi_event = dev;
> +	struct mhi_event *mhi_event = priv;
>  	struct mhi_controller *mhi_cntrl = mhi_event->mhi_cntrl;
> +	struct device *dev = &mhi_cntrl->mhi_dev->dev;
>  	struct mhi_event_ctxt *er_ctxt =
>  		&mhi_cntrl->mhi_ctxt->er_ctxt[mhi_event->er_index];
>  	struct mhi_ring *ev_ring = &mhi_event->ring;
> @@ -454,8 +455,20 @@ irqreturn_t mhi_irq_handler(int irq_number, void *dev)
>  
>  		if (mhi_dev)
>  			mhi_notify(mhi_dev, MHI_CB_PENDING_DATA);
> -	} else {
> +
> +		return IRQ_HANDLED;
> +	}
> +
> +	switch (mhi_event->priority) {
> +	case MHI_ER_PRIORITY_HI:

This could be,

	/* Use high priority tasklet for high priority event ring */
	if (!mhi_event->priority)
		tasklet_hi_schedule(&mhi_event->task);
	else
		tasklet_schedule(&mhi_event->task);

Thanks,
Mani

> +		tasklet_hi_schedule(&mhi_event->task);
> +		break;
> +	case MHI_ER_PRIORITY_DEFAULT:
>  		tasklet_schedule(&mhi_event->task);
> +		break;
> +	default:
> +		dev_err(dev, "Skip event of unknown priority\n");
> +		break;
>  	}
>  
>  	return IRQ_HANDLED;
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 86cea52..25ee312 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -198,6 +198,16 @@ enum mhi_er_data_type {
>  };
>  
>  /**
> + * enum mhi_er_priority - Event ring processing priority
> + * @MHI_ER_PRIORITY_HI: processed by hi-priority tasklet
> + * @MHI_ER_PRIORITY_DEFAULT: processed by regular tasklet
> + */
> +enum mhi_er_priority {
> +	MHI_ER_PRIORITY_HI,
> +	MHI_ER_PRIORITY_DEFAULT,
> +};
> +
> +/**
>   * enum mhi_db_brst_mode - Doorbell mode
>   * @MHI_DB_BRST_DISABLE: Burst mode disable
>   * @MHI_DB_BRST_ENABLE: Burst mode enable
> @@ -250,7 +260,7 @@ struct mhi_channel_config {
>   * @irq_moderation_ms: Delay irq for additional events to be aggregated
>   * @irq: IRQ associated with this ring
>   * @channel: Dedicated channel number. U32_MAX indicates a non-dedicated ring
> - * @priority: Priority of this ring. Use 1 for now
> + * @priority: Processing priority of this ring.
>   * @mode: Doorbell mode
>   * @data_type: Type of data this ring will process
>   * @hardware_event: This ring is associated with hardware channels
> @@ -262,7 +272,7 @@ struct mhi_event_config {
>  	u32 irq_moderation_ms;
>  	u32 irq;
>  	u32 channel;
> -	u32 priority;
> +	enum mhi_er_priority priority;
>  	enum mhi_db_brst_mode mode;
>  	enum mhi_er_data_type data_type;
>  	bool hardware_event;
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
Bhaumik Bhatt June 18, 2021, 5:17 p.m. UTC | #2 
Hi Mani,

On 2021-06-18 12:03 AM, Manivannan Sadhasivam wrote:
> On Thu, Jun 17, 2021 at 02:30:32PM -0700, Bhaumik Bhatt wrote:
>> From: Hemant Kumar <hemantk@codeaurora.org>
>> 
>> Event ring priorities are currently set to 1 and are unused.
>> Default processing priority for event rings is set to regular
>> tasklet. Controllers can choose to use high priority tasklet
>> scheduling for certain event rings critical for processing such
>> as ones transporting control information if they wish to avoid
>> with system scheduling delays for those packets. In order to
>> support these use cases, allow controllers to set event ring
>> priority to high. This patch only adds support and does not
>> enable usage of these priorities.
>> 
>> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
>> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
>> ---
>>  drivers/bus/mhi/core/internal.h |  2 +-
>>  drivers/bus/mhi/core/main.c     | 19 ++++++++++++++++---
>>  include/linux/mhi.h             | 14 ++++++++++++--
>>  3 files changed, 29 insertions(+), 6 deletions(-)
>> 
>> diff --git a/drivers/bus/mhi/core/internal.h 
>> b/drivers/bus/mhi/core/internal.h
>> index 672052f..666e102 100644
>> --- a/drivers/bus/mhi/core/internal.h
>> +++ b/drivers/bus/mhi/core/internal.h
>> @@ -535,7 +535,7 @@ struct mhi_event {
>>  	u32 intmod;
>>  	u32 irq;
>>  	int chan; /* this event ring is dedicated to a channel (optional) */
>> -	u32 priority;
>> +	enum mhi_er_priority priority;
> 
> Instead of using enum for priorities, can we just make use of the
> existing "priority" field? Since the existing controllers set it to 
> "1",
> can we use "0" as the high priority?
> 
> This way we don't need to change the controller drivers.
> 
I agree but the reasons to do the enum approach was to allow for future
expansion of the handling if it becomes necessary and provide clarity 
for
the field.

I can always do it this way for now and we can have the enum for another
time but would prefer updating what we have now.
>>  	enum mhi_er_data_type data_type;
>>  	struct mhi_ring ring;
>>  	struct db_cfg db_cfg;
>> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
>> index 8ac73f9..bfc9776 100644
>> --- a/drivers/bus/mhi/core/main.c
>> +++ b/drivers/bus/mhi/core/main.c
>> @@ -425,10 +425,11 @@ void mhi_create_devices(struct mhi_controller 
>> *mhi_cntrl)
>>  	}
>>  }
>> 
>> -irqreturn_t mhi_irq_handler(int irq_number, void *dev)
>> +irqreturn_t mhi_irq_handler(int irq_number, void *priv)
>>  {
>> -	struct mhi_event *mhi_event = dev;
>> +	struct mhi_event *mhi_event = priv;
>>  	struct mhi_controller *mhi_cntrl = mhi_event->mhi_cntrl;
>> +	struct device *dev = &mhi_cntrl->mhi_dev->dev;
>>  	struct mhi_event_ctxt *er_ctxt =
>>  		&mhi_cntrl->mhi_ctxt->er_ctxt[mhi_event->er_index];
>>  	struct mhi_ring *ev_ring = &mhi_event->ring;
>> @@ -454,8 +455,20 @@ irqreturn_t mhi_irq_handler(int irq_number, void 
>> *dev)
>> 
>>  		if (mhi_dev)
>>  			mhi_notify(mhi_dev, MHI_CB_PENDING_DATA);
>> -	} else {
>> +
>> +		return IRQ_HANDLED;
>> +	}
>> +
>> +	switch (mhi_event->priority) {
>> +	case MHI_ER_PRIORITY_HI:
> 
> This could be,
> 
> 	/* Use high priority tasklet for high priority event ring */
> 	if (!mhi_event->priority)
> 		tasklet_hi_schedule(&mhi_event->task);
> 	else
> 		tasklet_schedule(&mhi_event->task);
> 
> Thanks,
> Mani
> 
Yes, this works too if we keep the current non-enum approach.
>> +		tasklet_hi_schedule(&mhi_event->task);
>> +		break;
>> +	case MHI_ER_PRIORITY_DEFAULT:
>>  		tasklet_schedule(&mhi_event->task);
>> +		break;
>> +	default:
>> +		dev_err(dev, "Skip event of unknown priority\n");
>> +		break;
>>  	}
>> 
>>  	return IRQ_HANDLED;
>> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
>> index 86cea52..25ee312 100644
>> --- a/include/linux/mhi.h
>> +++ b/include/linux/mhi.h
>> @@ -198,6 +198,16 @@ enum mhi_er_data_type {
>>  };
>> 
>>  /**
>> + * enum mhi_er_priority - Event ring processing priority
>> + * @MHI_ER_PRIORITY_HI: processed by hi-priority tasklet
>> + * @MHI_ER_PRIORITY_DEFAULT: processed by regular tasklet
>> + */
>> +enum mhi_er_priority {
>> +	MHI_ER_PRIORITY_HI,
>> +	MHI_ER_PRIORITY_DEFAULT,
>> +};
>> +
>> +/**
>>   * enum mhi_db_brst_mode - Doorbell mode
>>   * @MHI_DB_BRST_DISABLE: Burst mode disable
>>   * @MHI_DB_BRST_ENABLE: Burst mode enable
>> @@ -250,7 +260,7 @@ struct mhi_channel_config {
>>   * @irq_moderation_ms: Delay irq for additional events to be 
>> aggregated
>>   * @irq: IRQ associated with this ring
>>   * @channel: Dedicated channel number. U32_MAX indicates a 
>> non-dedicated ring
>> - * @priority: Priority of this ring. Use 1 for now
>> + * @priority: Processing priority of this ring.
>>   * @mode: Doorbell mode
>>   * @data_type: Type of data this ring will process
>>   * @hardware_event: This ring is associated with hardware channels
>> @@ -262,7 +272,7 @@ struct mhi_event_config {
>>  	u32 irq_moderation_ms;
>>  	u32 irq;
>>  	u32 channel;
>> -	u32 priority;
>> +	enum mhi_er_priority priority;
>>  	enum mhi_db_brst_mode mode;
>>  	enum mhi_er_data_type data_type;
>>  	bool hardware_event;
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>> 
Existing controllers would be fine.

Do you think we have a problem if a new controller blindly inputs a "0" 
in
the priority not knowing the impact of it?

If you give me a go ahead, I can make these changes in v2 and leave the 
enum
stuff out.

Thanks,
Bhaumik
---
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum,
a Linux Foundation Collaborative Project
Manivannan Sadhasivam June 18, 2021, 5:31 p.m. UTC | #3 
On Fri, Jun 18, 2021 at 10:17:59AM -0700, Bhaumik Bhatt wrote:
> Hi Mani,
> 
> On 2021-06-18 12:03 AM, Manivannan Sadhasivam wrote:
> > On Thu, Jun 17, 2021 at 02:30:32PM -0700, Bhaumik Bhatt wrote:
> > > From: Hemant Kumar <hemantk@codeaurora.org>
> > > 
> > > Event ring priorities are currently set to 1 and are unused.
> > > Default processing priority for event rings is set to regular
> > > tasklet. Controllers can choose to use high priority tasklet
> > > scheduling for certain event rings critical for processing such
> > > as ones transporting control information if they wish to avoid
> > > with system scheduling delays for those packets. In order to
> > > support these use cases, allow controllers to set event ring
> > > priority to high. This patch only adds support and does not
> > > enable usage of these priorities.
> > > 
> > > Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> > > Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> > > ---
> > >  drivers/bus/mhi/core/internal.h |  2 +-
> > >  drivers/bus/mhi/core/main.c     | 19 ++++++++++++++++---
> > >  include/linux/mhi.h             | 14 ++++++++++++--
> > >  3 files changed, 29 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/bus/mhi/core/internal.h
> > > b/drivers/bus/mhi/core/internal.h
> > > index 672052f..666e102 100644
> > > --- a/drivers/bus/mhi/core/internal.h
> > > +++ b/drivers/bus/mhi/core/internal.h
> > > @@ -535,7 +535,7 @@ struct mhi_event {
> > >  	u32 intmod;
> > >  	u32 irq;
> > >  	int chan; /* this event ring is dedicated to a channel (optional) */
> > > -	u32 priority;
> > > +	enum mhi_er_priority priority;
> > 
> > Instead of using enum for priorities, can we just make use of the
> > existing "priority" field? Since the existing controllers set it to "1",
> > can we use "0" as the high priority?
> > 
> > This way we don't need to change the controller drivers.
> > 
> I agree but the reasons to do the enum approach was to allow for future
> expansion of the handling if it becomes necessary and provide clarity for
> the field.
> 
> I can always do it this way for now and we can have the enum for another
> time but would prefer updating what we have now.

Yeah, let's deal with it later once the necessity arises.

> > >  	enum mhi_er_data_type data_type;
> > >  	struct mhi_ring ring;
> > >  	struct db_cfg db_cfg;
> > > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> > > index 8ac73f9..bfc9776 100644
> > > --- a/drivers/bus/mhi/core/main.c
> > > +++ b/drivers/bus/mhi/core/main.c
> > > @@ -425,10 +425,11 @@ void mhi_create_devices(struct mhi_controller
> > > *mhi_cntrl)
> > >  	}
> > >  }
> > > 

[...]

> Existing controllers would be fine.
> 
> Do you think we have a problem if a new controller blindly inputs a "0" in
> the priority not knowing the impact of it?
> 

We should document it in the kernel doc for the struct field and that
should be enough. We can't do much if people doesn't read the doc ;)

Thanks,
Mani

> If you give me a go ahead, I can make these changes in v2 and leave the enum
> stuff out.
> 
> Thanks,
> Bhaumik
> ---
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
Bhaumik Bhatt June 18, 2021, 5:43 p.m. UTC | #4 
Hi Mani,
On 2021-06-18 10:31 AM, Manivannan Sadhasivam wrote:
> On Fri, Jun 18, 2021 at 10:17:59AM -0700, Bhaumik Bhatt wrote:
>> Hi Mani,
>> 
>> On 2021-06-18 12:03 AM, Manivannan Sadhasivam wrote:
>> > On Thu, Jun 17, 2021 at 02:30:32PM -0700, Bhaumik Bhatt wrote:
>> > > From: Hemant Kumar <hemantk@codeaurora.org>
>> > >
>> > > Event ring priorities are currently set to 1 and are unused.
>> > > Default processing priority for event rings is set to regular
>> > > tasklet. Controllers can choose to use high priority tasklet
>> > > scheduling for certain event rings critical for processing such
>> > > as ones transporting control information if they wish to avoid
>> > > with system scheduling delays for those packets. In order to
>> > > support these use cases, allow controllers to set event ring
>> > > priority to high. This patch only adds support and does not
>> > > enable usage of these priorities.
>> > >
>> > > Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
>> > > Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
>> > > ---
>> > >  drivers/bus/mhi/core/internal.h |  2 +-
>> > >  drivers/bus/mhi/core/main.c     | 19 ++++++++++++++++---
>> > >  include/linux/mhi.h             | 14 ++++++++++++--
>> > >  3 files changed, 29 insertions(+), 6 deletions(-)
>> > >
>> > > diff --git a/drivers/bus/mhi/core/internal.h
>> > > b/drivers/bus/mhi/core/internal.h
>> > > index 672052f..666e102 100644
>> > > --- a/drivers/bus/mhi/core/internal.h
>> > > +++ b/drivers/bus/mhi/core/internal.h
>> > > @@ -535,7 +535,7 @@ struct mhi_event {
>> > >  	u32 intmod;
>> > >  	u32 irq;
>> > >  	int chan; /* this event ring is dedicated to a channel (optional) */
>> > > -	u32 priority;
>> > > +	enum mhi_er_priority priority;
>> >
>> > Instead of using enum for priorities, can we just make use of the
>> > existing "priority" field? Since the existing controllers set it to "1",
>> > can we use "0" as the high priority?
>> >
>> > This way we don't need to change the controller drivers.
>> >
>> I agree but the reasons to do the enum approach was to allow for 
>> future
>> expansion of the handling if it becomes necessary and provide clarity 
>> for
>> the field.
>> 
>> I can always do it this way for now and we can have the enum for 
>> another
>> time but would prefer updating what we have now.
> 
> Yeah, let's deal with it later once the necessity arises.
> 
Sure. I will make the v2.

>> > >  	enum mhi_er_data_type data_type;
>> > >  	struct mhi_ring ring;
>> > >  	struct db_cfg db_cfg;
>> > > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
>> > > index 8ac73f9..bfc9776 100644
>> > > --- a/drivers/bus/mhi/core/main.c
>> > > +++ b/drivers/bus/mhi/core/main.c
>> > > @@ -425,10 +425,11 @@ void mhi_create_devices(struct mhi_controller
>> > > *mhi_cntrl)
>> > >  	}
>> > >  }
>> > >
> 
> [...]
> 
>> Existing controllers would be fine.
>> 
>> Do you think we have a problem if a new controller blindly inputs a 
>> "0" in
>> the priority not knowing the impact of it?
>> 
> 
> We should document it in the kernel doc for the struct field and that
> should be enough. We can't do much if people doesn't read the doc ;)
> 
> Thanks,
> Mani
> 
Totally agree :)

>> If you give me a go ahead, I can make these changes in v2 and leave 
>> the enum
>> stuff out.
>> 
>> Thanks,
>> Bhaumik
>> ---
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project

Thanks,
Bhaumik
---
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum,
a Linux Foundation Collaborative Project
diff mbox series

Patch

diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 672052f..666e102 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -535,7 +535,7 @@  struct mhi_event {
 	u32 intmod;
 	u32 irq;
 	int chan; /* this event ring is dedicated to a channel (optional) */
-	u32 priority;
+	enum mhi_er_priority priority;
 	enum mhi_er_data_type data_type;
 	struct mhi_ring ring;
 	struct db_cfg db_cfg;
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 8ac73f9..bfc9776 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -425,10 +425,11 @@  void mhi_create_devices(struct mhi_controller *mhi_cntrl)
 	}
 }
 
-irqreturn_t mhi_irq_handler(int irq_number, void *dev)
+irqreturn_t mhi_irq_handler(int irq_number, void *priv)
 {
-	struct mhi_event *mhi_event = dev;
+	struct mhi_event *mhi_event = priv;
 	struct mhi_controller *mhi_cntrl = mhi_event->mhi_cntrl;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
 	struct mhi_event_ctxt *er_ctxt =
 		&mhi_cntrl->mhi_ctxt->er_ctxt[mhi_event->er_index];
 	struct mhi_ring *ev_ring = &mhi_event->ring;
@@ -454,8 +455,20 @@  irqreturn_t mhi_irq_handler(int irq_number, void *dev)
 
 		if (mhi_dev)
 			mhi_notify(mhi_dev, MHI_CB_PENDING_DATA);
-	} else {
+
+		return IRQ_HANDLED;
+	}
+
+	switch (mhi_event->priority) {
+	case MHI_ER_PRIORITY_HI:
+		tasklet_hi_schedule(&mhi_event->task);
+		break;
+	case MHI_ER_PRIORITY_DEFAULT:
 		tasklet_schedule(&mhi_event->task);
+		break;
+	default:
+		dev_err(dev, "Skip event of unknown priority\n");
+		break;
 	}
 
 	return IRQ_HANDLED;
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 86cea52..25ee312 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -198,6 +198,16 @@  enum mhi_er_data_type {
 };
 
 /**
+ * enum mhi_er_priority - Event ring processing priority
+ * @MHI_ER_PRIORITY_HI: processed by hi-priority tasklet
+ * @MHI_ER_PRIORITY_DEFAULT: processed by regular tasklet
+ */
+enum mhi_er_priority {
+	MHI_ER_PRIORITY_HI,
+	MHI_ER_PRIORITY_DEFAULT,
+};
+
+/**
  * enum mhi_db_brst_mode - Doorbell mode
  * @MHI_DB_BRST_DISABLE: Burst mode disable
  * @MHI_DB_BRST_ENABLE: Burst mode enable
@@ -250,7 +260,7 @@  struct mhi_channel_config {
  * @irq_moderation_ms: Delay irq for additional events to be aggregated
  * @irq: IRQ associated with this ring
  * @channel: Dedicated channel number. U32_MAX indicates a non-dedicated ring
- * @priority: Priority of this ring. Use 1 for now
+ * @priority: Processing priority of this ring.
  * @mode: Doorbell mode
  * @data_type: Type of data this ring will process
  * @hardware_event: This ring is associated with hardware channels
@@ -262,7 +272,7 @@  struct mhi_event_config {
 	u32 irq_moderation_ms;
 	u32 irq;
 	u32 channel;
-	u32 priority;
+	enum mhi_er_priority priority;
 	enum mhi_db_brst_mode mode;
 	enum mhi_er_data_type data_type;
 	bool hardware_event;