Hi Krzysztof,
On 7/24/20 7:08 PM, Krzysztof Kozlowski wrote:
Document scope of the mutex used by driver.
Signed-off-by: Krzysztof Kozlowski <[email protected]>
---
It seems mutex was introduced to protect:
1. setting actual frequency/voltage,
2. dmc->curr_rate (in exynos5_dmc_get_cur_freq()).
However dmc->curr_rate in exynos5_dmc_get_status() is not protected. Is
it a bug?
The callback get_dev_status() from devfreq->profile, which here is the
exynos5_dmc_get_status() should be already called with devfreq->lock
mutex hold, like e.g from simple_ondemand governor or directly
using update_devfreq exported function:
update_devfreq()
->get_target_freq()
devfreq_update_stats()
df->profile->get_dev_status()
The dmc->curr_rate is also used from sysfs interface from devfreq.
The local dmc lock serializes also this use case (when the HW freq
has changed but not set yet into curr_rate.
---
drivers/memory/samsung/exynos5422-dmc.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/memory/samsung/exynos5422-dmc.c
b/drivers/memory/samsung/exynos5422-dmc.c
index 93e9c2429c0d..0388066a7d96 100644
--- a/drivers/memory/samsung/exynos5422-dmc.c
+++ b/drivers/memory/samsung/exynos5422-dmc.c
@@ -114,6 +114,7 @@ struct exynos5_dmc {
void __iomem *base_drexi0;
void __iomem *base_drexi1;
struct regmap *clk_regmap;
+ /* Protects curr_rate and frequency/voltage setting section */
struct mutex lock;
unsigned long curr_rate;
unsigned long curr_volt;
I assume this missing comment for the lock was required by some scripts.
In this case LGTM:
Reviewed-by: Lukasz Luba <[email protected]>
Regards,
Lukasz
