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From: Linus Walleij on 2 Mar 2010 15:20
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(a)stericsson.com>
---
drivers/dma/coh901318.c | 42 ++++++++++++++++++++++++++++--------------
1 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c
index 64a9372..b962cf1 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);
@@ -637,9 +643,18 @@ static void dma_tasklet(unsigned long data)
}

if (cohc->nbr_active_done)
+ /*
+ * 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.
+ */
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;
--
1.6.3.3

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Prev: perf archive: Don't try to collect files without a build-id
Next: [RFC v2 05/10] snet: introduce snet_event