rapidio/tsi721_dma: fix pending transaction queue handling

Fix pending DMA request queue handling to avoid broken ordering during
concurrent request submissions.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 32 insertions, 30 deletions

diff --git a/drivers/rapidio/devices/tsi721.h b/drivers/rapidio/devices/tsi721.h
index f81d01149b39..d675a44ffc17 100644
--- a/drivers/rapidio/devices/tsi721.h
+++ b/drivers/rapidio/devices/tsi721.h
@@ -674,7 +674,7 @@ struct tsi721_bdma_chan {
         struct dma_chan         dchan;
         struct tsi721_tx_desc   *tx_desc;
         spinlock_t              lock;
-        struct list_head        active_list;
+        struct tsi721_tx_desc   *active_tx;
         struct list_head        queue;
         struct list_head        free_list;
         struct tasklet_struct   tasklet;
diff --git a/drivers/rapidio/devices/tsi721_dma.c b/drivers/rapidio/devices/tsi721_dma.c
index 47295940a868..500e1e044c36 100644
--- a/drivers/rapidio/devices/tsi721_dma.c
+++ b/drivers/rapidio/devices/tsi721_dma.c
@@ -63,14 +63,6 @@ struct tsi721_tx_desc *to_tsi721_desc(struct dma_async_tx_descriptor *txd)
         return container_of(txd, struct tsi721_tx_desc, txd);
 }
 
-static inline
-struct tsi721_tx_desc *tsi721_dma_first_active(
-                                struct tsi721_bdma_chan *bdma_chan)
-{
-        return list_first_entry(&bdma_chan->active_list,
-                                struct tsi721_tx_desc, desc_node);
-}
-
 static int tsi721_bdma_ch_init(struct tsi721_bdma_chan *bdma_chan, int bd_num)
 {
         struct tsi721_dma_desc *bd_ptr;
@@ -534,23 +526,30 @@ entry_done:
         return err;
 }
 
-static void tsi721_advance_work(struct tsi721_bdma_chan *bdma_chan)
+static void tsi721_advance_work(struct tsi721_bdma_chan *bdma_chan,
+                                struct tsi721_tx_desc *desc)
 {
-        struct tsi721_tx_desc *desc;
         int err;
 
         dev_dbg(bdma_chan->dchan.device->dev, "%s: Enter\n", __func__);
 
+        if (!tsi721_dma_is_idle(bdma_chan))
+                return;
+
         /*
-         * If there are any new transactions in the queue add them
-         * into the processing list
-         */
-        if (!list_empty(&bdma_chan->queue))
-                list_splice_init(&bdma_chan->queue, &bdma_chan->active_list);
+         * If there is no data transfer in progress, fetch new descriptor from
+         * the pending queue.
+        */
+
+        if (desc == NULL && bdma_chan->active_tx == NULL &&
+                                        !list_empty(&bdma_chan->queue)) {
+                desc = list_first_entry(&bdma_chan->queue,
+                                        struct tsi721_tx_desc, desc_node);
+                list_del_init((&desc->desc_node));
+                bdma_chan->active_tx = desc;
+        }
 
-        /* Start new transaction (if available) */
-        if (!list_empty(&bdma_chan->active_list)) {
-                desc = tsi721_dma_first_active(bdma_chan);
+        if (desc) {
                 err = tsi721_submit_sg(desc);
                 if (!err)
                         tsi721_start_dma(bdma_chan);
@@ -581,6 +580,10 @@ static void tsi721_dma_tasklet(unsigned long data)
                 dev_err(bdma_chan->dchan.device->dev,
                         "%s: DMA ERROR - DMAC%d_STS = 0x%x\n",
                         __func__, bdma_chan->id, dmac_sts);
+
+                spin_lock(&bdma_chan->lock);
+                bdma_chan->active_tx = NULL;
+                spin_unlock(&bdma_chan->lock);
         }
 
         if (dmac_int & TSI721_DMAC_INT_STFULL) {
@@ -594,7 +597,7 @@ static void tsi721_dma_tasklet(unsigned long data)
 
                 tsi721_clr_stat(bdma_chan);
                 spin_lock(&bdma_chan->lock);
-                desc = tsi721_dma_first_active(bdma_chan);
+                desc = bdma_chan->active_tx;
 
                 if (desc->sg_len == 0) {
                         dma_async_tx_callback callback = NULL;
@@ -606,14 +609,15 @@ static void tsi721_dma_tasklet(unsigned long data)
                                 callback = desc->txd.callback;
                                 param = desc->txd.callback_param;
                         }
-                        list_move(&desc->desc_node, &bdma_chan->free_list);
+                        list_add(&desc->desc_node, &bdma_chan->free_list);
+                        bdma_chan->active_tx = NULL;
                         spin_unlock(&bdma_chan->lock);
                         if (callback)
                                 callback(param);
                         spin_lock(&bdma_chan->lock);
                 }
 
-                tsi721_advance_work(bdma_chan);
+                tsi721_advance_work(bdma_chan, bdma_chan->active_tx);
                 spin_unlock(&bdma_chan->lock);
         }
 
@@ -720,9 +724,6 @@ static void tsi721_free_chan_resources(struct dma_chan *dchan)
         if (bdma_chan->bd_base == NULL)
                 return;
 
-        BUG_ON(!list_empty(&bdma_chan->active_list));
-        BUG_ON(!list_empty(&bdma_chan->queue));
-
         tsi721_bdma_interrupt_enable(bdma_chan, 0);
         bdma_chan->active = false;
         tsi721_sync_dma_irq(bdma_chan);
@@ -745,11 +746,11 @@ static void tsi721_issue_pending(struct dma_chan *dchan)
 
         dev_dbg(dchan->device->dev, "%s: Enter\n", __func__);
 
+        spin_lock_bh(&bdma_chan->lock);
         if (tsi721_dma_is_idle(bdma_chan) && bdma_chan->active) {
-                spin_lock_bh(&bdma_chan->lock);
-                tsi721_advance_work(bdma_chan);
-                spin_unlock_bh(&bdma_chan->lock);
+                tsi721_advance_work(bdma_chan, NULL);
         }
+        spin_unlock_bh(&bdma_chan->lock);
 }
 
 static
@@ -839,7 +840,8 @@ static int tsi721_terminate_all(struct dma_chan *dchan)
                 } while ((dmac_int & TSI721_DMAC_INT_SUSP) == 0);
         }
 
-        list_splice_init(&bdma_chan->active_list, &list);
+        if (bdma_chan->active_tx)
+                list_add(&bdma_chan->active_tx->desc_node, &list);
         list_splice_init(&bdma_chan->queue, &list);
 
         list_for_each_entry_safe(desc, _d, &list, desc_node)
@@ -875,7 +877,7 @@ int tsi721_register_dma(struct tsi721_device *priv)
 
                 spin_lock_init(&bdma_chan->lock);
 
-                INIT_LIST_HEAD(&bdma_chan->active_list);
+                bdma_chan->active_tx = NULL;
                 INIT_LIST_HEAD(&bdma_chan->queue);
                 INIT_LIST_HEAD(&bdma_chan->free_list);