On 19/04/16 16:45, Mathieu Poirier wrote:
On 19 April 2016 at 07:19, Suzuki K Poulose <[email protected]> wrote:
On 12/04/16 18:54, Mathieu Poirier wrote:
Moving tmc_drvdata::enable to a local_t mode. That way the
sink interface is aware of it's orgin and the foundation for
mutual exclusion between the sysFS and Perf interface can be
laid out.
Signed-off-by: Mathieu Poirier <[email protected]>
---
drivers/hwtracing/coresight/coresight-tmc-etf.c | 28
++++++++++++++++++-------
drivers/hwtracing/coresight/coresight-tmc-etr.c | 24
++++++++++++++++-----
drivers/hwtracing/coresight/coresight-tmc.h | 4 ++--
3 files changed, 42 insertions(+), 14 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c
b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 7cb287ef7b9e..5908000e1ae0 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -110,6 +110,7 @@ static int tmc_enable_etf_sink(struct coresight_device
*csdev, u32 mode)
{
bool allocated = false;
char *buf = NULL;
+ u32 val;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
@@ -146,6 +147,15 @@ fast_path:
return -EBUSY;
}
+ val = local_xchg(&drvdata->mode, mode);
+ /*
+ * In sysFS mode we can have multiple writers per sink. Since
this
+ * sink is already enabled no memory is needed and the HW need not
be
+ * touched.
+ */
+ if (val == CS_MODE_SYSFS)
+ goto out;
+
We are not dropping the spinlock in this case. Are we ?
Definitely - thanks for pointing that out.
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h
b/drivers/hwtracing/coresight/coresight-tmc.h
index 80096fa75326..821bdf150ac9 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -100,7 +100,7 @@ enum tmc_mem_intf_width {
* @paddr: DMA start location in RAM.
* @vaddr: virtual representation of @paddr.
* @size: @buf size.
- * @enable: this TMC is being used.
+ * @mode: how this TMC is being used.
* @config_type: TMC variant, must be of type @tmc_config_type.
* @trigger_cntr: amount of words to store after a trigger.
*/
@@ -116,7 +116,7 @@ struct tmc_drvdata {
dma_addr_t paddr;
void __iomem *vaddr;
u32 size;
- bool enable;
+ local_t mode;
Since we always deal with the mode under the spinlock, do we really need
this to
be local_t ? Or do we plan to get rid of the lock ?
You are correct, using a local_t variable isn't strictly needed here. But:
1) It greatly simplifies the code.
+1
2) I'm really hoping one day we can do without the spinlocks, though I
don't know when that will happen.
Get back to me if you're resolute on switching the local_t to a normal type.
No, leave it as it is, as you said, it does simplify the code.
