DMAENGINE: COH 901 318 cleanups

This cleans up the some debug code that was not working in the
COH 901 318 driver, adds some helpful comments and rearrange the
code a bit.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 28 insertions, 14 deletions

diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
index 64a937262a4..f1bf4f74ad8 100644
--- a/drivers/dma/coh901318.c
+++ b/drivers/dma/coh901318.c
@@ -80,18 +80,16 @@ struct coh901318_chan {
 static void coh901318_list_print(struct coh901318_chan *cohc,
                                  struct coh901318_lli *lli)
 {
-        struct coh901318_lli *l;
-        dma_addr_t addr =  virt_to_phys(lli);
+        struct coh901318_lli *l = lli;
         int i = 0;
 
-        while (addr) {
-                l = phys_to_virt(addr);
+        while (l) {
                 dev_vdbg(COHC_2_DEV(cohc), "i %d, lli %p, ctrl 0x%x, src 0x%x"
-                         ", dst 0x%x, link 0x%x link_virt 0x%p\n",
+                         ", dst 0x%x, link 0x%x virt_link_addr 0x%p\n",
                          i, l, l->control, l->src_addr, l->dst_addr,
-                         l->link_addr, phys_to_virt(l->link_addr));
+                         l->link_addr, l->virt_link_addr);
                 i++;
-                addr = l->link_addr;
+                l = l->virt_link_addr;
         }
 }
 
@@ -125,7 +123,7 @@ static int coh901318_debugfs_read(struct file *file, char __user *buf,
                 goto err_kmalloc;
         tmp = dev_buf;
 
-        tmp += sprintf(tmp, "DMA -- enable dma channels\n");
+        tmp += sprintf(tmp, "DMA -- enabled dma channels\n");
 
         for (i = 0; i < debugfs_dma_base->platform->max_channels; i++)
                 if (started_channels & (1 << i))
@@ -592,6 +590,10 @@ static struct coh901318_desc *coh901318_queue_start(struct coh901318_chan *cohc)
         return cohd_que;
 }
 
+/*
+ * This tasklet is called from the interrupt handler to
+ * handle each descriptor (DMA job) that is sent to a channel.
+ */
 static void dma_tasklet(unsigned long data)
 {
         struct coh901318_chan *cohc = (struct coh901318_chan *) data;
@@ -600,9 +602,13 @@ static void dma_tasklet(unsigned long data)
         dma_async_tx_callback callback;
         void *callback_param;
 
+        dev_vdbg(COHC_2_DEV(cohc), "[%s] chan_id %d"
+                 " nbr_active_done %ld\n", __func__,
+                 cohc->id, cohc->nbr_active_done);
+
         spin_lock_irqsave(&cohc->lock, flags);
 
-        /* get first active entry from list */
+        /* get first active descriptor entry from list */
         cohd_fin = coh901318_first_active_get(cohc);
 
         BUG_ON(cohd_fin->pending_irqs == 0);
@@ -636,10 +642,19 @@ static void dma_tasklet(unsigned long data)
                 coh901318_desc_free(cohc, cohd_fin);
         }
 
+        /*
+         * If another interrupt fired while the tasklet was scheduling,
+         * we don't get called twice, so we have this number of active
+         * counter that keep track of the number of IRQs expected to
+         * be handled for this channel. If there happen to be more than
+         * one IRQ to be ack:ed, we simply schedule this tasklet again.
+         */
         if (cohc->nbr_active_done)
                 cohc->nbr_active_done--;
 
         if (cohc->nbr_active_done) {
+                dev_dbg(COHC_2_DEV(cohc), "scheduling tasklet again, new IRQs "
+                        "came in while we were scheduling this tasklet\n");
                 if (cohc_chan_conf(cohc)->priority_high)
                         tasklet_hi_schedule(&cohc->tasklet);
                 else
@@ -994,6 +1009,7 @@ coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                 len += factor;
         }
 
+        pr_debug("Allocate %d lli:s for this transfer\n", len);
         data = coh901318_lli_alloc(&cohc->base->pool, len);
 
         if (data == NULL)
@@ -1092,9 +1108,8 @@ coh901318_terminate_all(struct dma_chan *chan)
                 /* release the lli allocation*/
                 coh901318_lli_free(&cohc->base->pool, &cohd->data);
 
-                coh901318_desc_remove(cohd);
-
                 /* return desc to free-list */
+                coh901318_desc_remove(cohd);
                 coh901318_desc_free(cohc, cohd);
         }
 
@@ -1102,9 +1117,8 @@ coh901318_terminate_all(struct dma_chan *chan)
                 /* release the lli allocation*/
                 coh901318_lli_free(&cohc->base->pool, &cohd->data);
 
-                coh901318_desc_remove(cohd);
-
                 /* return desc to free-list */
+                coh901318_desc_remove(cohd);
                 coh901318_desc_free(cohc, cohd);
         }
 
@@ -1259,7 +1273,7 @@ static int __init coh901318_probe(struct platform_device *pdev)
         if (err)
                 goto err_register_memcpy;
 
-        dev_dbg(&pdev->dev, "Initialized COH901318 DMA on virtual base 0x%08x\n",
+        dev_info(&pdev->dev, "Initialized COH901318 DMA on virtual base 0x%08x\n",
                 (u32) base->virtbase);
 
         return err;