net: ethernet: ti: davinci_cpdma: split descs num between all channels

Tx channels share same pool of descriptors. Thus one channel can
block another if pool is emptied by one. But, the shaper should
decide which channel is allowed to send packets. To avoid such
impact of one channel on another, let every channel to have its
own piece of pool.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Reviewed-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 44 insertions, 2 deletions

diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
index cf72b3390d85..167fd659319d 100644
--- a/drivers/net/ethernet/ti/davinci_cpdma.c
+++ b/drivers/net/ethernet/ti/davinci_cpdma.c
@@ -104,6 +104,7 @@ struct cpdma_ctlr {
 	struct cpdma_desc_pool	*pool;
 	spinlock_t		lock;
 	struct cpdma_chan	*channels[2 * CPDMA_MAX_CHANNELS];
+	int chan_num;
 };
 
 struct cpdma_chan {
@@ -256,6 +257,7 @@ struct cpdma_ctlr *cpdma_ctlr_create(struct cpdma_params *params)
 	ctlr->state = CPDMA_STATE_IDLE;
 	ctlr->params = *params;
 	ctlr->dev = params->dev;
+	ctlr->chan_num = 0;
 	spin_lock_init(&ctlr->lock);
 
 	ctlr->pool = cpdma_desc_pool_create(ctlr->dev,
@@ -399,6 +401,31 @@ void cpdma_ctlr_eoi(struct cpdma_ctlr *ctlr, u32 value)
 }
 EXPORT_SYMBOL_GPL(cpdma_ctlr_eoi);
 
+/**
+ * cpdma_chan_split_pool - Splits ctrl pool between all channels.
+ * Has to be called under ctlr lock
+ */
+static void cpdma_chan_split_pool(struct cpdma_ctlr *ctlr)
+{
+	struct cpdma_desc_pool *pool = ctlr->pool;
+	struct cpdma_chan *chan;
+	int ch_desc_num;
+	int i;
+
+	if (!ctlr->chan_num)
+		return;
+
+	/* calculate average size of pool slice */
+	ch_desc_num = pool->num_desc / ctlr->chan_num;
+
+	/* split ctlr pool */
+	for (i = 0; i < ARRAY_SIZE(ctlr->channels); i++) {
+		chan = ctlr->channels[i];
+		if (chan)
+			chan->desc_num = ch_desc_num;
+	}
+}
+
 struct cpdma_chan *cpdma_chan_create(struct cpdma_ctlr *ctlr, int chan_num,
 				     cpdma_handler_fn handler)
 {
@@ -447,14 +474,25 @@ struct cpdma_chan *cpdma_chan_create(struct cpdma_ctlr *ctlr, int chan_num,
 	spin_lock_init(&chan->lock);
 
 	ctlr->channels[chan_num] = chan;
+	ctlr->chan_num++;
+
+	cpdma_chan_split_pool(ctlr);
+
 	spin_unlock_irqrestore(&ctlr->lock, flags);
 	return chan;
 }
 EXPORT_SYMBOL_GPL(cpdma_chan_create);
 
-int cpdma_chan_get_rx_buf_num(struct cpdma_ctlr *ctlr)
+int cpdma_chan_get_rx_buf_num(struct cpdma_chan *chan)
 {
-	return ctlr->pool->num_desc / 2;
+	unsigned long flags;
+	int desc_num;
+
+	spin_lock_irqsave(&chan->lock, flags);
+	desc_num = chan->desc_num;
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	return desc_num;
 }
 EXPORT_SYMBOL_GPL(cpdma_chan_get_rx_buf_num);
 
@@ -471,6 +509,10 @@ int cpdma_chan_destroy(struct cpdma_chan *chan)
 	if (chan->state != CPDMA_STATE_IDLE)
 		cpdma_chan_stop(chan);
 	ctlr->channels[chan->chan_num] = NULL;
+	ctlr->chan_num--;
+
+	cpdma_chan_split_pool(ctlr);
+
 	spin_unlock_irqrestore(&ctlr->lock, flags);
 	return 0;
 }