bcm2835-dma: Limit cyclic transfers on lite channels to 32k

Transfers larger than 32k cause repeated clicking with I2S soundcards.
The exact reason is yet unknown, so limit to 32k as bcm2708-dmaengine
did as an intermediate fix.

Author: HiassofT

drivers/dma/bcm2835-dma.c

@@ -141,6 +141,12 @@ struct bcm2835_desc {
  */
 #define MAX_LITE_TRANSFER	(SZ_64K - 4)
 
+/*
+ * Transfers larger than 32k cause issues with the bcm2708-i2s driver,
+ * so limit transfer size to 32k as bcm2708-dmaengine did.
+ */
+#define MAX_CYCLIC_LITE_TRANSFER	SZ_32K
+
 static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d)
 {
 	return container_of(d, struct bcm2835_dmadev, ddev);
@@ -397,7 +403,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic(
 
 	d->dir = direction;
 	if (c->ch >= 8) /* LITE channel */
-		max_size = MAX_LITE_TRANSFER;
+		max_size = MAX_CYCLIC_LITE_TRANSFER;
 	else
 		max_size = MAX_NORMAL_TRANSFER;
 	period_len = min(period_len, max_size);