Re: [PATCH v3 4/7] clk: qcom: gdsc: call runtime PM functions for the provider device
From: Dmitry Baryshkov
Date: Fri Jul 09 2021 - 18:11:37 EST
On 09/07/2021 21:54, Bjorn Andersson wrote:
On Fri 09 Jul 12:31 CDT 2021, Dmitry Baryshkov wrote:
In order to properly handle runtime PM status of the provider device,
call pm_runtime_get/pm_runtime_put on the clock controller device.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
drivers/clk/qcom/gdsc.c | 66 ++++++++++++++++++++++++++++++++++++++---
drivers/clk/qcom/gdsc.h | 2 ++
2 files changed, 64 insertions(+), 4 deletions(-)
diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index ccd36617d067..6bec31fccb09 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/reset-controller.h>
@@ -50,6 +51,30 @@ enum gdsc_status {
GDSC_ON
};
+static int gdsc_pm_runtime_get(struct gdsc *sc)
+{
+ int ret;
+
+ if (!sc->rpm_dev)
+ return 0;
+
+ ret = pm_runtime_get_sync(sc->rpm_dev);
+ if (ret < 0) {
+ pm_runtime_put_noidle(sc->rpm_dev);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int gdsc_pm_runtime_put(struct gdsc *sc)
+{
+ if (!sc->rpm_dev)
+ return 0;
+
+ return pm_runtime_put_sync(sc->rpm_dev);
+}
+
/* Returns 1 if GDSC status is status, 0 if not, and < 0 on error */
static int gdsc_check_status(struct gdsc *sc, enum gdsc_status status)
{
@@ -232,9 +257,8 @@ static void gdsc_retain_ff_on(struct gdsc *sc)
regmap_update_bits(sc->regmap, sc->gdscr, mask, mask);
}
-static int gdsc_enable(struct generic_pm_domain *domain)
+static int _gdsc_enable(struct gdsc *sc)
{
- struct gdsc *sc = domain_to_gdsc(domain);
int ret;
if (sc->pwrsts == PWRSTS_ON)
@@ -290,11 +314,28 @@ static int gdsc_enable(struct generic_pm_domain *domain)
return 0;
}
-static int gdsc_disable(struct generic_pm_domain *domain)
+static int gdsc_enable(struct generic_pm_domain *domain)
{
struct gdsc *sc = domain_to_gdsc(domain);
int ret;
+ ret = gdsc_pm_runtime_get(sc);
+ if (ret)
+ return ret;
+
+ ret = _gdsc_enable(sc);
+ if (ret) {
+ gdsc_pm_runtime_put(sc);
I presume what you do here is to leave the pm_runtime state of dispcc
active if we succeeded in enabling the gdsc. But the gdsc is a subdomain
of the parent domain, so the framework should take case of its
dependency.
So the reason for gdsc_pm_runtime_get()/put() in this code path is so
that you can access the dispcc registers, i.e. I think you should
get()/put() regardless of the return value.
pm domain code will handle enabling MMCX, so this code is not required
strictly speaking. Ulf suggested adding it back, so I followed the
suggestion. Maybe I misunderstood his suggestion.
putting pm_runtime after gdsc_enable does not sound like a logical case.
However it would simplify code a bit. Let me try...
+ return ret;
+ }
+
+ return 0;
+}
+
+static int _gdsc_disable(struct gdsc *sc)
+{
+ int ret;
+
if (sc->pwrsts == PWRSTS_ON)
return gdsc_assert_reset(sc);
@@ -329,6 +370,18 @@ static int gdsc_disable(struct generic_pm_domain *domain)
return 0;
}
+static int gdsc_disable(struct generic_pm_domain *domain)
+{
+ struct gdsc *sc = domain_to_gdsc(domain);
+ int ret;
+
If the gdsc is found to be on at initialization, the next operation that
will happen is gdsc_disable() and as you didn't activate the pm_runtime
state in gdsc_init() you would in theory get here with registers
unaccessible.
In practice though, the active gdsc should through the being a subdomain
of the parent domain keep power on for you, so you won't notice this
issue.
Nice catch.
But as above, I think you should wrap _gdsc_disable() in a get()/put()
pair.
+ ret = _gdsc_disable(sc);
+ if (ret)
+ return ret;
+
+ return gdsc_pm_runtime_put(sc);
+}
+
static int gdsc_init(struct gdsc *sc)
{
u32 mask, val;
@@ -425,6 +478,8 @@ int gdsc_register(struct gdsc_desc *desc,
for (i = 0; i < num; i++) {
if (!scs[i])
continue;
+ if (pm_runtime_enabled(dev))
+ scs[i]->rpm_dev = dev;
scs[i]->regmap = regmap;
scs[i]->rcdev = rcdev;
ret = gdsc_init(scs[i]);
@@ -486,7 +541,10 @@ void gdsc_unregister(struct gdsc_desc *desc)
*/
int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain)
{
+ struct gdsc *sc = domain_to_gdsc(domain);
+
/* Do nothing but give genpd the impression that we were successful */
- return 0;
+ /* Get the runtime PM device only */
+ return gdsc_pm_runtime_get(sc);
Per above, if you let the framework deal with the gdsc's dependencies on
the parent domain and you only get()/put() for the sake of dispcc then
you don't need you don't need to do this to keep the subsequent
gdsc_disable() in balance.
}
EXPORT_SYMBOL_GPL(gdsc_gx_do_nothing_enable);
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index 5bb396b344d1..a82982df0a55 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -25,6 +25,7 @@ struct reset_controller_dev;
* @resets: ids of resets associated with this gdsc
* @reset_count: number of @resets
* @rcdev: reset controller
+ * @rpm_dev: runtime PM device
*/
struct gdsc {
struct generic_pm_domain pd;
@@ -58,6 +59,7 @@ struct gdsc {
const char *supply;
struct regulator *rsupply;
+ struct device *rpm_dev;
This isn't just the "runtime pm device", it's the device this gdsc is
associated with. So "dev" sounds sufficient to me, but that requires
that you have a separate bool rpm_enabled to remember if
pm_runtime_enabled() was true during probe.
So unless we need "dev" for something else this might be sufficient.
Regards,
Bjorn
};
struct gdsc_desc {
--
2.30.2
--
With best wishes
Dmitry