From: Arnd Bergmann <arnd@xxxxxxxx>
in dma_slave_config, which is incompatible with the way that the
dmaengine API normally works.
I've had a closer look at the existing code now and found that all
slave drivers that pass a slave_id in dma_slave_config for SH do that
right after passing the same ID into shdma_chan_filter, so we can just
rely on that. However, the various shdma drivers currently do not
remember the slave ID that was passed into the filter function when
used in non-DT mode and only check the value to find a matching channel,
unlike all other drivers.
There might still be drivers that are not part of the kernel that rely
on setting the slave_id to some other value, so to be on the safe side,
this adds another 'real_slave_id' field to shdma_chan that remembers
the ID and uses it when a driver passes a zero slave_id in dma_slave_config,
like most drivers do.
Eventually, the real_slave_id and slave_id fields should just get merged
into one field, but that requires other changes.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
---
v3 -> v4
- no change
drivers/dma/sh/shdma-base.c | 73 +++++++++++++++++++++++++++++++------------
include/linux/shdma-base.h | 1 +
2 files changed, 54 insertions(+), 20 deletions(-)
diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index 8ee383d..10fcaba 100644
--- a/drivers/dma/sh/shdma-base.c
+++ b/drivers/dma/sh/shdma-base.c
@@ -171,8 +171,7 @@ static struct shdma_desc *shdma_get_desc(struct shdma_chan *schan)
return NULL;
}
-static int shdma_setup_slave(struct shdma_chan *schan, int slave_id,
- dma_addr_t slave_addr)
+static int shdma_setup_slave(struct shdma_chan *schan, dma_addr_t slave_addr)
{
struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
const struct shdma_ops *ops = sdev->ops;
@@ -183,25 +182,23 @@ static int shdma_setup_slave(struct shdma_chan *schan, int slave_id,
ret = ops->set_slave(schan, match, slave_addr, true);
if (ret < 0)
return ret;
-
- slave_id = schan->slave_id;
} else {
- match = slave_id;
+ match = schan->real_slave_id;
}
- if (slave_id < 0 || slave_id >= slave_num)
+ if (schan->real_slave_id < 0 || schan->real_slave_id >= slave_num)
return -EINVAL;
- if (test_and_set_bit(slave_id, shdma_slave_used))
+ if (test_and_set_bit(schan->real_slave_id, shdma_slave_used))
return -EBUSY;
ret = ops->set_slave(schan, match, slave_addr, false);
if (ret < 0) {
- clear_bit(slave_id, shdma_slave_used);
+ clear_bit(schan->real_slave_id, shdma_slave_used);
return ret;
}
- schan->slave_id = slave_id;
+ schan->slave_id = schan->real_slave_id;
return 0;
}
@@ -221,10 +218,12 @@ static int shdma_alloc_chan_resources(struct dma_chan *chan)
*/
if (slave) {
/* Legacy mode: .private is set in filter */
- ret = shdma_setup_slave(schan, slave->slave_id, 0);
+ schan->real_slave_id = slave->slave_id;
+ ret = shdma_setup_slave(schan, 0);
if (ret < 0)
goto esetslave;
} else {
+ /* Normal mode: real_slave_id was set by filter */
schan->slave_id = -EINVAL;
}
@@ -258,11 +257,14 @@ esetslave:
/*
* This is the standard shdma filter function to be used as a replacement to the
- * "old" method, using the .private pointer. If for some reason you allocate a
- * channel without slave data, use something like ERR_PTR(-EINVAL) as a filter
+ * "old" method, using the .private pointer.
+ * You always have to pass a valid slave id as the argument, old drivers that
+ * pass ERR_PTR(-EINVAL) as a filter parameter and set it up in dma_slave_config
+ * need to be updated so we can remove the slave_id field from dma_slave_config.
* parameter. If this filter is used, the slave driver, after calling
* dma_request_channel(), will also have to call dmaengine_slave_config() with
- * .slave_id, .direction, and either .src_addr or .dst_addr set.
+ * .direction, and either .src_addr or .dst_addr set.
+ *
* NOTE: this filter doesn't support multiple DMAC drivers with the DMA_SLAVE
* capability! If this becomes a requirement, hardware glue drivers, using this
* services would have to provide their own filters, which first would check
@@ -276,7 +278,7 @@ bool shdma_chan_filter(struct dma_chan *chan, void *arg)
{
struct shdma_chan *schan;
struct shdma_dev *sdev;
- int match = (long)arg;
+ int slave_id = (long)arg;
int ret;
/* Only support channels handled by this driver. */
@@ -284,19 +286,39 @@ bool shdma_chan_filter(struct dma_chan *chan, void *arg)
shdma_alloc_chan_resources)
return false;
- if (match < 0)
+ schan = to_shdma_chan(chan);
+ sdev = to_shdma_dev(chan->device);
+
+ /*
+ * For DT, the schan->slave_id field is generated by the
+ * set_slave function from the slave ID that is passed in
+ * from xlate. For the non-DT case, the slave ID is
+ * directly passed into the filter function by the driver
+ */
+ if (schan->dev->of_node) {
+ ret = sdev->ops->set_slave(schan, slave_id, 0, true);
+ if (ret < 0)
+ return false;
+
+ schan->real_slave_id = schan->slave_id;
+ return true;
+ }
+
+ if (slave_id < 0) {
/* No slave requested - arbitrary channel */
+ dev_warn(sdev->dma_dev.dev, "invalid slave ID passed to dma_request_slave\n");
return true;
+ }
- schan = to_shdma_chan(chan);
- if (!schan->dev->of_node && match >= slave_num)
+ if (slave_id >= slave_num)
return false;
- sdev = to_shdma_dev(schan->dma_chan.device);
- ret = sdev->ops->set_slave(schan, match, 0, true);
+ ret = sdev->ops->set_slave(schan, slave_id, 0, true);
if (ret < 0)
return false;
+ schan->real_slave_id = slave_id;
+
return true;
}
EXPORT_SYMBOL(shdma_chan_filter);
@@ -452,6 +474,8 @@ static void shdma_free_chan_resources(struct dma_chan *chan)
chan->private = NULL;
}
+ schan->real_slave_id = 0;
+
spin_lock_irq(&schan->chan_lock);
list_splice_init(&schan->ld_free, &list);
@@ -764,11 +788,20 @@ static int shdma_config(struct dma_chan *chan,
*/
if (!config)
return -EINVAL;
+
+ /*
+ * overriding the slave_id through dma_slave_config is deprecated,
+ * but possibly some out-of-tree drivers still do it.
+ */
+ if (WARN_ON_ONCE(config->slave_id &&
+ config->slave_id != schan->real_slave_id))
+ schan->real_slave_id = config->slave_id;
+
/*
* We could lock this, but you shouldn't be configuring the
* channel, while using it...
*/
- return shdma_setup_slave(schan, config->slave_id,
+ return shdma_setup_slave(schan,
config->direction == DMA_DEV_TO_MEM ?
config->src_addr : config->dst_addr);
}
diff --git a/include/linux/shdma-base.h b/include/linux/shdma-base.h
index abdf1f2..dd0ba50 100644
--- a/include/linux/shdma-base.h
+++ b/include/linux/shdma-base.h
@@ -69,6 +69,7 @@ struct shdma_chan {
int id; /* Raw id of this channel */
int irq; /* Channel IRQ */
int slave_id; /* Client ID for slave DMA */
+ int real_slave_id; /* argument passed to filter function */
int hw_req; /* DMA request line for slave DMA - same
* as MID/RID, used with DT */
enum shdma_pm_state pm_state;
--
1.7.9.5
--
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