dmaengine: ti: k3-udma: Add missing locking

Recent kernels complain about a missing lock in k3-udma.c when the lock
validator is enabled:

[    4.128073] WARNING: CPU: 0 PID: 746 at drivers/dma/ti/../virt-dma.h:169 udma_start.isra.0+0x34/0x238
[    4.137352] CPU: 0 UID: 0 PID: 746 Comm: kworker/0:3 Not tainted 6.12.9-arm64 #28
[    4.144867] Hardware name: pp-v12 (DT)
[    4.148648] Workqueue: events udma_check_tx_completion
[    4.153841] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    4.160834] pc : udma_start.isra.0+0x34/0x238
[    4.165227] lr : udma_start.isra.0+0x30/0x238
[    4.169618] sp : ffffffc083cabcf0
[    4.172963] x29: ffffffc083cabcf0 x28: 0000000000000000 x27: ffffff800001b005
[    4.180167] x26: ffffffc0812f0000 x25: 0000000000000000 x24: 0000000000000000
[    4.187370] x23: 0000000000000001 x22: 00000000e21eabe9 x21: ffffff8000fa0670
[    4.194571] x20: ffffff8001b6bf00 x19: ffffff8000fa0430 x18: ffffffc083b95030
[    4.201773] x17: 0000000000000000 x16: 00000000f0000000 x15: 0000000000000048
[    4.208976] x14: 0000000000000048 x13: 0000000000000000 x12: 0000000000000001
[    4.216179] x11: ffffffc08151a240 x10: 0000000000003ea1 x9 : ffffffc08046ab68
[    4.223381] x8 : ffffffc083cabac0 x7 : ffffffc081df3718 x6 : 0000000000029fc8
[    4.230583] x5 : ffffffc0817ee6d8 x4 : 0000000000000bc0 x3 : 0000000000000000
[    4.237784] x2 : 0000000000000000 x1 : 00000000001fffff x0 : 0000000000000000
[    4.244986] Call trace:
[    4.247463]  udma_start.isra.0+0x34/0x238
[    4.251509]  udma_check_tx_completion+0xd0/0xdc
[    4.256076]  process_one_work+0x244/0x3fc
[    4.260129]  process_scheduled_works+0x6c/0x74
[    4.264610]  worker_thread+0x150/0x1dc
[    4.268398]  kthread+0xd8/0xe8
[    4.271492]  ret_from_fork+0x10/0x20
[    4.275107] irq event stamp: 220
[    4.278363] hardirqs last  enabled at (219): [<ffffffc080a27c7c>] _raw_spin_unlock_irq+0x38/0x50
[    4.287183] hardirqs last disabled at (220): [<ffffffc080a1c154>] el1_dbg+0x24/0x50
[    4.294879] softirqs last  enabled at (182): [<ffffffc080037e68>] handle_softirqs+0x1c0/0x3cc
[    4.303437] softirqs last disabled at (177): [<ffffffc080010170>] __do_softirq+0x1c/0x28
[    4.311559] ---[ end trace 0000000000000000 ]---

This commit adds the missing locking.

Fixes: 25dcb5d ("dmaengine: ti: New driver for K3 UDMA")
Cc: Peter Ujfalusi <[email protected]>
Cc: Vignesh Raghavendra <[email protected]>
Cc: Vinod Koul <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Ronald Wahl <[email protected]>
Acked-by: Peter Ujfalusi <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

Author: Ronald Wahl

drivers/dma/ti/k3-udma.c

@@ -1091,8 +1091,11 @@ static void udma_check_tx_completion(struct work_struct *work)
 	u32 residue_diff;
 	ktime_t time_diff;
 	unsigned long delay;
+	unsigned long flags;
 
 	while (1) {
+		spin_lock_irqsave(&uc->vc.lock, flags);
+
 		if (uc->desc) {
 			/* Get previous residue and time stamp */
 			residue_diff = uc->tx_drain.residue;
@@ -1127,6 +1130,8 @@ static void udma_check_tx_completion(struct work_struct *work)
 				break;
 			}
 
+			spin_unlock_irqrestore(&uc->vc.lock, flags);
+
 			usleep_range(ktime_to_us(delay),
 				     ktime_to_us(delay) + 10);
 			continue;
@@ -1143,6 +1148,8 @@ static void udma_check_tx_completion(struct work_struct *work)
 
 		break;
 	}
+
+	spin_unlock_irqrestore(&uc->vc.lock, flags);
 }
 
 static irqreturn_t udma_ring_irq_handler(int irq, void *data)