[PATCH v1 5/9] coresight: Avoid enable programming clock duplicately

From: Leo Yan
Date: Thu Mar 27 2025 - 07:40:48 EST


The programming clock is enabled by AMBA bus driver before a dynamic
probe. As a result, a CoreSight driver may redundantly enable the same
clock.

To avoid this, add a check for device type and skip enabling the
programming clock for AMBA devices. The returned NULL pointer will be
tolerated by the drivers.

Fixes: 73d779a03a76 ("coresight: etm4x: Change etm4_platform_driver driver for MMIO devices")
Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
---
include/linux/coresight.h | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index b888f6ed59b2..26eb4a61b992 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -476,15 +476,18 @@ static inline bool is_coresight_device(void __iomem *base)
* Returns:
*
* clk - Clock is found and enabled
+ * NULL - Clock is not needed as it is managed by the AMBA bus driver
* ERROR - Clock is found but failed to enable
*/
static inline struct clk *coresight_get_enable_apb_pclk(struct device *dev)
{
- struct clk *pclk;
+ struct clk *pclk = NULL;

- pclk = devm_clk_get_enabled(dev, "apb_pclk");
- if (IS_ERR(pclk))
- pclk = devm_clk_get_enabled(dev, "apb");
+ if (!dev_is_amba(dev)) {
+ pclk = devm_clk_get_enabled(dev, "apb_pclk");
+ if (IS_ERR(pclk))
+ pclk = devm_clk_get_enabled(dev, "apb");
+ }

return pclk;
}
--
2.34.1