From 02f09e080b34d08954757737a7a6e28f8c5ea060 Mon Sep 17 00:00:00 2001
From: Artem Mygaiev <joculator@gmail.com>
Date: Sun, 12 May 2024 00:48:07 +0200
Subject: [PATCH] Simplify interrupt message processing

---
 fl2000_interrupt.c | 94 ++++++++++++++--------------------------------
 1 file changed, 28 insertions(+), 66 deletions(-)

diff --git a/fl2000_interrupt.c b/fl2000_interrupt.c
index df2a14a..8523749 100644
--- a/fl2000_interrupt.c
+++ b/fl2000_interrupt.c
@@ -11,63 +11,44 @@
 struct fl2000_intr {
 	struct usb_device *usb_dev;
 	struct drm_device *drm;
-	u8 poll_interval;
-	struct urb *urb;
 	u8 *buf;
-	dma_addr_t transfer_dma;
+	int pipe;
 	struct work_struct work;
 	struct workqueue_struct *work_queue;
 };
 
 static void fl2000_intr_work(struct work_struct *work)
 {
-	int event;
 	struct fl2000_intr *intr = container_of(work, struct fl2000_intr, work);
-
-	event = fl2000_check_interrupt(intr->usb_dev);
-	if (event)
-		drm_kms_helper_hotplug_event(intr->drm);
+	struct usb_device *usb_dev = intr->usb_dev;
+
+	while (1) {
+		int ret;
+
+		/* Receive interrupt message */
+		ret = usb_interrupt_msg(usb_dev, intr->pipe, intr->buf, INTR_BUFSIZE, NULL, 0);
+		if (ret) {
+			dev_err(&usb_dev->dev, "Interrupt message failed (%d)", ret);
+			/* TODO: Signal fault to system and start shutdown of usb_dev */
+			return;
+		}
+
+		ret = fl2000_check_interrupt(intr->usb_dev);
+		if (ret)
+			drm_kms_helper_hotplug_event(intr->drm);
+	}
 }
 
 static void fl2000_intr_release(struct device *dev, void *res)
 {
 	struct fl2000_intr *intr = res;
-	struct usb_device *usb_dev = to_usb_device(dev);
 
-	usb_poison_urb(intr->urb);
+	UNUSED(dev);
+
 	cancel_work_sync(&intr->work);
 	destroy_workqueue(intr->work_queue);
-	usb_free_coherent(usb_dev, INTR_BUFSIZE, intr->buf, intr->transfer_dma);
-	usb_free_urb(intr->urb);
-}
-
-static void fl2000_intr_completion(struct urb *urb)
-{
-	int ret;
-	struct usb_device *usb_dev = urb->dev;
-	struct fl2000_intr *intr = urb->context;
-
-	ret = fl2000_urb_status(usb_dev, urb->status, urb->pipe);
-	if (ret) {
-		dev_err(&usb_dev->dev, "Stopping interrupts");
-		return;
-	}
-
-	/* This possibly involves reading I2C registers, etc. so better to schedule a work queue */
-	queue_work(intr->work_queue, &intr->work);
-
-	/* For interrupt URBs, as part of successful URB submission urb->interval is modified to
-	 * reflect the actual transfer period used, so we need to restore it
-	 */
-	urb->interval = intr->poll_interval;
-	urb->start_frame = -1;
-
-	/* Restart urb */
-	ret = fl2000_submit_urb(urb);
-	if (ret) {
-		dev_err(&usb_dev->dev, "URB submission failed (%d)", ret);
-		/* TODO: Signal fault to system and start shutdown of usb_dev */
-	}
+	
+	kfree(intr->buf);
 }
 
 /**
@@ -95,6 +76,8 @@ struct fl2000_intr *fl2000_intr_create(struct usb_device *usb_dev, struct drm_de
 		dev_err(&usb_dev->dev, "Cannot find interrupt endpoint");
 		return ERR_PTR(ret);
 	}
+	ret = usb_endpoint_num(desc);
+	intr->pipe = usb_rcvintpipe(usb_dev, ret);
 
 	intr = devres_alloc(&fl2000_intr_release, sizeof(*intr), GFP_KERNEL);
 	if (!intr) {
@@ -103,45 +86,24 @@ struct fl2000_intr *fl2000_intr_create(struct usb_device *usb_dev, struct drm_de
 	}
 	devres_add(&usb_dev->dev, intr);
 
-	intr->poll_interval = desc->bInterval;
 	intr->usb_dev = usb_dev;
 	intr->drm = drm;
-	INIT_WORK(&intr->work, &fl2000_intr_work);
-
-	intr->urb = usb_alloc_urb(0, GFP_ATOMIC);
-	if (!intr->urb) {
-		dev_err(&usb_dev->dev, "Allocate interrupt URB failed");
-		devres_release(&usb_dev->dev, fl2000_intr_release, NULL, NULL);
-		return ERR_PTR(-ENOMEM);
-	}
-
-	intr->buf = usb_alloc_coherent(usb_dev, INTR_BUFSIZE, GFP_KERNEL, &intr->transfer_dma);
+	intr->buf = kmalloc(INTR_BUFSIZE, GFP_KERNEL);
 	if (!intr->buf) {
 		dev_err(&usb_dev->dev, "Cannot allocate interrupt data");
 		devres_release(&usb_dev->dev, fl2000_intr_release, NULL, NULL);
 		return ERR_PTR(-ENOMEM);
 	}
 
+	/* This possibly involves reading I2C registers, etc. so better to schedule a work queue */
+	INIT_WORK(&intr->work, &fl2000_intr_work);
 	intr->work_queue = create_workqueue("fl2000_interrupt");
 	if (!intr->work_queue) {
 		dev_err(&usb_dev->dev, "Create interrupt workqueue failed");
 		devres_release(&usb_dev->dev, fl2000_intr_release, NULL, NULL);
 		return ERR_PTR(-ENOMEM);
 	}
-
-	/* Interrupt URB configuration is static, including allocated buffer */
-	usb_fill_int_urb(intr->urb, usb_dev, usb_rcvintpipe(usb_dev, 3), intr->buf, INTR_BUFSIZE,
-			 fl2000_intr_completion, intr, intr->poll_interval);
-	intr->urb->transfer_dma = intr->transfer_dma;
-	intr->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; /* use urb->transfer_dma */
-
-	/* Start checking for interrupts */
-	ret = usb_submit_urb(intr->urb, GFP_KERNEL);
-	if (ret) {
-		dev_err(&usb_dev->dev, "URB submission failed");
-		devres_release(&usb_dev->dev, fl2000_intr_release, NULL, NULL);
-		return ERR_PTR(ret);
-	}
+	queue_work(intr->work_queue, &intr->work);
 
 	return intr;
 }