Hi,
Changes since v1:
- Removed dev_warn() for kasprintf in both patch
- Added Reviewed-by from Geert to the first patch
- Use much more simplified fops for the debugfs file (via DEFINE_SHOW_ATTRIBUTE)
- do not allow modification to dma_device_list while the debugfs file is read
- rename the slave_name to dbg_client_name (it is only for debugging)
- print information about dma_router if it is used by the channel
- Formating of the output slightly changed
As I have mentioned on the symlink patch earlier I like how the gpio's debugfs
shows in one place information.
These patches are on top of Vinod's next (with the v2 fix for the symlink
support).
The first patch fixes and cleans up the symlink handling code a bit and the
second adds support for debugfs file:
On my board with audio and after a run with dmatest on 6 channels this is how
the information is presented about the DMA drivers:
# cat /sys/kernel/debug/dmaengine
dma0 (285c0000.dma-controller): number of channels: 96
dma1 (31150000.dma-controller): number of channels: 267
dma1chan0 | 2b00000.mcasp:tx
dma1chan1 | 2b00000.mcasp:rx
dma1chan2 | in-use
dma1chan3 | in-use
dma1chan4 | in-use
dma1chan5 | in-use
dma1chan6 | in-use
dma1chan7 | in-use
On dra7-evm after boot:
# cat /sys/kernel/debug/dmaengine
dma0 (43300000.edma): number of channels: 64
dma0chan0 | 48468000.mcasp:tx (via router: 4a002c78.dma-router)
dma0chan1 | 48468000.mcasp:rx (via router: 4a002c78.dma-router)
dma1 (4a056000.dma-controller): number of channels: 127
dma1chan0 | in-use
dma1chan1 | in-use
It shows the users (device name + channel name) of the channels. If it is not a
slave channel, then it only prints 'in-use' as no other information is
available for non save channels.
DMA drivers can implement the dbg_show callback to provide custom information
for their channels if needed.
Regards,
Peter
---
Peter Ujfalusi (2):
dmaengine: Cleanups for the slave <-> channel symlink support
dmaengine: Add basic debugfs support
drivers/dma/dmaengine.c | 84 ++++++++++++++++++++++++++++++++++-----
include/linux/dmaengine.h | 12 +++++-
2 files changed, 86 insertions(+), 10 deletions(-)
--
Peter
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
No need to use goto to jump over the
return chan ? chan : ERR_PTR(-EPROBE_DEFER);
We can just revert the check and return right there.
Do not fail the channel request if the chan->name allocation fails, but
print a warning about it.
Change the dev_err to dev_warn if sysfs_create_link() fails as it is not
fatal.
Only attempt to remove the DMA_SLAVE_NAME symlink if it is created - or it
was attempted to be created.
Signed-off-by: Peter Ujfalusi <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
---
drivers/dma/dmaengine.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 7b1cefc3213a..342d23132fca 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -756,22 +756,21 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name)
}
mutex_unlock(&dma_list_mutex);
- if (!IS_ERR_OR_NULL(chan))
- goto found;
-
- return chan ? chan : ERR_PTR(-EPROBE_DEFER);
+ if (IS_ERR_OR_NULL(chan))
+ return chan ? chan : ERR_PTR(-EPROBE_DEFER);
found:
- chan->slave = dev;
chan->name = kasprintf(GFP_KERNEL, "dma:%s", name);
if (!chan->name)
- return ERR_PTR(-ENOMEM);
+ return chan;
+ chan->slave = dev;
if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj,
DMA_SLAVE_NAME))
- dev_err(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
+ dev_warn(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name))
- dev_err(dev, "Cannot create DMA %s symlink\n", chan->name);
+ dev_warn(dev, "Cannot create DMA %s symlink\n", chan->name);
+
return chan;
}
EXPORT_SYMBOL_GPL(dma_request_chan);
@@ -830,13 +829,14 @@ void dma_release_channel(struct dma_chan *chan)
/* drop PRIVATE cap enabled by __dma_request_channel() */
if (--chan->device->privatecnt == 0)
dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask);
+
if (chan->slave) {
+ sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
sysfs_remove_link(&chan->slave->kobj, chan->name);
kfree(chan->name);
chan->name = NULL;
chan->slave = NULL;
}
- sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
mutex_unlock(&dma_list_mutex);
}
EXPORT_SYMBOL_GPL(dma_release_channel);
--
Peter
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
On 31-01-20, 11:38, Peter Ujfalusi wrote:
> No need to use goto to jump over the
> return chan ? chan : ERR_PTR(-EPROBE_DEFER);
> We can just revert the check and return right there.
>
> Do not fail the channel request if the chan->name allocation fails, but
> print a warning about it.
>
> Change the dev_err to dev_warn if sysfs_create_link() fails as it is not
> fatal.
>
> Only attempt to remove the DMA_SLAVE_NAME symlink if it is created - or it
> was attempted to be created.
Applied, thanks
--
~Vinod