usb: renesas: fix scheduling in atomic context bug

The current renesas_usbhs driver triggers

BUG: scheduling while atomic: ksoftirqd/0/3/0x00000102

with enabled CONFIG_DEBUG_ATOMIC_SLEEP, by submitting DMA transfers from
an atomic (tasklet) context, which is not supported by the shdma dmaengine
driver. Fix it by switching to a work.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/renesas_usbhs/fifo.c

@@ -765,9 +765,9 @@ static int __usbhsf_dma_map_ctrl(struct usbhs_pkt *pkt, int map)
 }
 
 static void usbhsf_dma_complete(void *arg);
-static void usbhsf_dma_prepare_tasklet(unsigned long data)
+static void xfer_work(struct work_struct *work)
 {
-	struct usbhs_pkt *pkt = (struct usbhs_pkt *)data;
+	struct usbhs_pkt *pkt = container_of(work, struct usbhs_pkt, work);
 	struct usbhs_pipe *pipe = pkt->pipe;
 	struct usbhs_fifo *fifo = usbhs_pipe_to_fifo(pipe);
 	struct usbhs_priv *priv = usbhs_pipe_to_priv(pipe);
@@ -847,11 +847,8 @@ static int usbhsf_dma_prepare_push(struct usbhs_pkt *pkt, int *is_done)
 
 	pkt->trans = len;
 
-	tasklet_init(&fifo->tasklet,
-		     usbhsf_dma_prepare_tasklet,
-		     (unsigned long)pkt);
-
-	tasklet_schedule(&fifo->tasklet);
+	INIT_WORK(&pkt->work, xfer_work);
+	schedule_work(&pkt->work);
 
 	return 0;
 
@@ -941,11 +938,8 @@ static int usbhsf_dma_try_pop(struct usbhs_pkt *pkt, int *is_done)
 
 	pkt->trans = len;
 
-	tasklet_init(&fifo->tasklet,
-		     usbhsf_dma_prepare_tasklet,
-		     (unsigned long)pkt);
-
-	tasklet_schedule(&fifo->tasklet);
+	INIT_WORK(&pkt->work, xfer_work);
+	schedule_work(&pkt->work);
 
 	return 0;
 

drivers/usb/renesas_usbhs/fifo.h

@@ -19,6 +19,7 @@
 
 #include <linux/interrupt.h>
 #include <linux/sh_dma.h>
+#include <linux/workqueue.h>
 #include <asm/dma.h>
 #include "pipe.h"
 
@@ -31,7 +32,6 @@ struct usbhs_fifo {
 	u32 ctr;	/* xFIFOCTR */
 
 	struct usbhs_pipe	*pipe;
-	struct tasklet_struct	tasklet;
 
 	struct dma_chan		*tx_chan;
 	struct dma_chan		*rx_chan;
@@ -53,6 +53,7 @@ struct usbhs_pkt {
 	struct usbhs_pkt_handle *handler;
 	void (*done)(struct usbhs_priv *priv,
 		     struct usbhs_pkt *pkt);
+	struct work_struct work;
 	dma_addr_t dma;
 	void *buf;
 	int length;