linux-kernel - [PATCH v2] bus: mhi: core: Add support for processing priority of event ring

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Date:   Fri, 18 Jun 2021 15:05:03 -0700
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     manivannan.sadhasivam@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
        loic.poulain@...aro.org, Bhaumik Bhatt <bbhatt@...eaurora.org>
Subject: [PATCH v2] bus: mhi: core: Add support for processing priority of event ring

From: Hemant Kumar <hemantk@...eaurora.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
system scheduling delays for those packets. In order to support
these use cases, allow controllers to set event ring priority to
high.

Signed-off-by: Hemant Kumar <hemantk@...eaurora.org>
Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
---
 drivers/bus/mhi/core/init.c | 3 +--
 drivers/bus/mhi/core/main.c | 9 +++++++--
 include/linux/mhi.h         | 2 +-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index c81b377..4446760 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -673,8 +673,7 @@ static int parse_ev_cfg(struct mhi_controller *mhi_cntrl,
 				&mhi_cntrl->mhi_chan[mhi_event->chan];
 		}
 
-		/* Priority is fixed to 1 for now */
-		mhi_event->priority = 1;
+		mhi_event->priority = event_cfg->priority;
 
 		mhi_event->db_cfg.brstmode = event_cfg->mode;
 		if (MHI_INVALID_BRSTMODE(mhi_event->db_cfg.brstmode))
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 8ac73f9..3775c77 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -454,10 +454,15 @@ irqreturn_t mhi_irq_handler(int irq_number, void *dev)
 
 		if (mhi_dev)
 			mhi_notify(mhi_dev, MHI_CB_PENDING_DATA);
-	} else {
-		tasklet_schedule(&mhi_event->task);
+
+		return IRQ_HANDLED;
 	}
 
+	if (!mhi_event->priority)
+		tasklet_hi_schedule(&mhi_event->task);
+	else
+		tasklet_schedule(&mhi_event->task);
+
 	return IRQ_HANDLED;
 }
 
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 86cea52..bf23c21 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -250,7 +250,7 @@ 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. 0 is high and 1 is regular
  * @mode: Doorbell mode
  * @data_type: Type of data this ring will process
  * @hardware_event: This ring is associated with hardware channels
-- 
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