[PATCH v4 0/3] clk: qcom: Add support for multiple power-domains for a clock controller.

[PATCH v4 0/3] clk: qcom: Add support for multiple power-domains for a clock controller.

[Bryan O'Donoghue]

v4:
- Adds Bjorn's RB to first patch - Bjorn
- Drops the 'd' in "and int" - Bjorn
- Amends commit log of patch 3 to capture a number of open questions -
  Bjorn

- Link to v3: https://lore.kernel.org/r/20241126-b4-linux-next-24-11-18-clock-multiple-power-domains-v3-0-836dad33521a@linaro.org

v3:
- Fixes commit log "per which" - Bryan 
- Link to v2: https://lore.kernel.org/r/20241125-b4-linux-next-24-11-18-clock-multiple-power-domains-v2-0-a5e7554d7e45@linaro.org

v2:
The main change in this version is Bjorn's pointing out that pm_runtime_*
inside of the gdsc_enable/gdsc_disable path would be recursive and cause a
lockdep splat. Dmitry alluded to this too.

Bjorn pointed to stuff being done lower in the gdsc_register() routine that
might be a starting point.

I iterated around that idea and came up with patch #3. When a gdsc has no
parent and the pd_list is non-NULL then attach that orphan GDSC to the
clock controller power-domain list.

Existing subdomain code in gdsc_register() will connect the parent GDSCs in
the clock-controller to the clock-controller subdomain, the new code here
does that same job for a list of power-domains the clock controller depends
on.

To Dmitry's point about MMCX and MCX dependencies for the registers inside
of the clock controller, I have switched off all references in a test dtsi
and confirmed that accessing the clock-controller regs themselves isn't
required.

On the second point I also verified my test branch with lockdep on which
was a concern with the pm_domain version of this solution but I wanted to
cover it anyway with the new approach for completeness sake.

Here's the item-by-item list of changes:

- Adds a patch to capture pm_genpd_add_subdomain() result code - Bryan
- Changes changelog of second patch to remove singleton and generally
  to make the commit log easier to understand - Bjorn
- Uses demv_pm_domain_attach_list - Vlad
- Changes error check to if (ret < 0 && ret != -EEXIST) - Vlad
- Retains passing &pd_data instead of NULL - because NULL doesn't do
  the same thing - Bryan/Vlad
- Retains standalone function qcom_cc_pds_attach() because the pd_data
  enumeration looks neater in a standalone function - Bryan/Vlad
- Drops pm_runtime in favour of gdsc_add_subdomain_list() for each
  power-domain in the pd_list.
  The pd_list will be whatever is pointed to by power-domains = <>
  in the dtsi - Bjorn
- Link to v1: https://lore.kernel.org/r/20241118-b4-linux-next-24-11-18-clock-multiple-power-domains-v1-0-b7a2bd82ba37@linaro.org

v1:
On x1e80100 and it's SKUs the Camera Clock Controller - CAMCC has
multiple power-domains which power it. Usually with a single power-domain
the core platform code will automatically switch on the singleton
power-domain for you. If you have multiple power-domains for a device, in
this case the clock controller, you need to switch those power-domains
on/off yourself.

The clock controllers can also contain Global Distributed
Switch Controllers - GDSCs which themselves can be referenced from dtsi
nodes ultimately triggering a gdsc_en() in drivers/clk/qcom/gdsc.c.

As an example:

cci0: cci@ac4a000 {
	power-domains = <&camcc TITAN_TOP_GDSC>;
};

This series adds the support to attach a power-domain list to the
clock-controllers and the GDSCs those controllers provide so that in the
case of the above example gdsc_toggle_logic() will trigger the power-domain
list with pm_runtime_resume_and_get() and pm_runtime_put_sync()
respectively.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
Bryan O'Donoghue (3):
      clk: qcom: gdsc: Capture pm_genpd_add_subdomain result code
      clk: qcom: common: Add support for power-domain attachment
      clk: qcom: Support attaching GDSCs to multiple parents

 drivers/clk/qcom/common.c | 21 +++++++++++++++++++++
 drivers/clk/qcom/gdsc.c   | 41 +++++++++++++++++++++++++++++++++++++++--
 drivers/clk/qcom/gdsc.h   |  1 +
 3 files changed, 61 insertions(+), 2 deletions(-)
---
base-commit: 744cf71b8bdfcdd77aaf58395e068b7457634b2c
change-id: 20241118-b4-linux-next-24-11-18-clock-multiple-power-domains-a5f994dc452a

Best regards,
-- 
Bryan O'Donoghue <bryan.odonoghue@linaro.org>

[PATCH v4 1/3] clk: qcom: gdsc: Capture pm_genpd_add_subdomain result code

[Bryan O'Donoghue]

Adding a new clause to this if/else I noticed the existing usage of
pm_genpd_add_subdomain() wasn't capturing and returning the result code.

pm_genpd_add_subdomain() returns an int and can fail. Capture that result
code and throw it up the call stack if something goes wrong.

Fixes: 1b771839de05 ("clk: qcom: gdsc: enable optional power domain support")
Cc: stable@vger.kernel.org
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
 drivers/clk/qcom/gdsc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index fa5fe4c2a2ee7786c2e8858f3e41301f639e5d59..4fc6f957d0b846cc90e50ef243f23a7a27e66899 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -555,9 +555,11 @@ int gdsc_register(struct gdsc_desc *desc,
 		if (!scs[i])
 			continue;
 		if (scs[i]->parent)
-			pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
+			ret = pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
 		else if (!IS_ERR_OR_NULL(dev->pm_domain))
-			pm_genpd_add_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
+			ret = pm_genpd_add_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
+		if (ret)
+			return ret;
 	}
 
 	return of_genpd_add_provider_onecell(dev->of_node, data);

-- 
2.45.2

[PATCH v4 2/3] clk: qcom: common: Add support for power-domain attachment

[Bryan O'Donoghue]

Right now we support one power-domain per clock controller.
These single power-domains are switched on by the driver platform logic.

However when we have multiple power-domains attached to a clock-controller
that list of power-domains must be handled outside of driver platform
logic.

Use devm_pm_domain_attach_list() to automatically hook the list of given
power-domains in the dtsi for the clock-controller driver.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
 drivers/clk/qcom/common.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
index 33cc1f73c69d1f875a193aea0552902268dc8716..7727295c57c8f6672d46d2380e1ff5ec2ac68d42 100644
--- a/drivers/clk/qcom/common.c
+++ b/drivers/clk/qcom/common.c
@@ -22,6 +22,7 @@ struct qcom_cc {
 	struct qcom_reset_controller reset;
 	struct clk_regmap **rclks;
 	size_t num_rclks;
+	struct dev_pm_domain_list *pd_list;
 };
 
 const
@@ -283,6 +284,21 @@ static int qcom_cc_icc_register(struct device *dev,
 						     desc->num_icc_hws, icd);
 }
 
+static int qcom_cc_pds_attach(struct device *dev, struct qcom_cc *cc)
+{
+	struct dev_pm_domain_attach_data pd_data = {
+		.pd_names = 0,
+		.num_pd_names = 0,
+	};
+	int ret;
+
+	ret = devm_pm_domain_attach_list(dev, &pd_data, &cc->pd_list);
+	if (ret < 0 && ret != -EEXIST)
+		return ret;
+
+	return 0;
+}
+
 int qcom_cc_really_probe(struct device *dev,
 			 const struct qcom_cc_desc *desc, struct regmap *regmap)
 {
@@ -299,6 +315,10 @@ int qcom_cc_really_probe(struct device *dev,
 	if (!cc)
 		return -ENOMEM;
 
+	ret = qcom_cc_pds_attach(dev, cc);
+	if (ret)
+		return ret;
+
 	reset = &cc->reset;
 	reset->rcdev.of_node = dev->of_node;
 	reset->rcdev.ops = &qcom_reset_ops;

-- 
2.45.2

Re: [PATCH v4 2/3] clk: qcom: common: Add support for power-domain attachment

[Vladimir Zapolskiy]

On 11/27/24 17:53, Bryan O'Donoghue wrote:
> Right now we support one power-domain per clock controller.
> These single power-domains are switched on by the driver platform logic.
> 
> However when we have multiple power-domains attached to a clock-controller
> that list of power-domains must be handled outside of driver platform
> logic.
> 
> Use devm_pm_domain_attach_list() to automatically hook the list of given
> power-domains in the dtsi for the clock-controller driver.
> 
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>

Please simplify this change, please do not ignore patch reviews, if you
find it possible.

https://lore.kernel.org/all/8a33c0ff-0c6d-4995-b239-023d2a2c2af5@linaro.org/

--
Best wishes,
Vladimir

Re: [PATCH v4 2/3] clk: qcom: common: Add support for power-domain attachment

[Bryan O'Donoghue]

On 28/11/2024 12:09, Vladimir Zapolskiy wrote:
> Please simplify this change, please do not ignore patch reviews, if you
> find it possible.
> 
> https://lore.kernel.org/all/8a33c0ff-0c6d-4995- 
> b239-023d2a2c2af5@linaro.org/

You want this inlined ?

It seems like a stylistic ask but OK.

---
bod

Re: [PATCH v4 2/3] clk: qcom: common: Add support for power-domain attachment

[Vladimir Zapolskiy]

On 11/28/24 14:16, Bryan O'Donoghue wrote:
> On 28/11/2024 12:09, Vladimir Zapolskiy wrote:
>> Please simplify this change, please do not ignore patch reviews, if you
>> find it possible.
>>
>> https://lore.kernel.org/all/8a33c0ff-0c6d-4995-
>> b239-023d2a2c2af5@linaro.org/
> 
> You want this inlined ?

Yes, please. A simpler version should be preferred, by any metrics 3 lines
of code are better than 20 lines of code plus a new added function.

Thank you for understanding.

--
Best wishes,
Vladimir

[PATCH v4 3/3] clk: qcom: Support attaching GDSCs to multiple parents

[Bryan O'Donoghue]

When a clock-controller has multiple power-domains we need to attach
parent GDSCs in that clock-controller as subdomains of each of the
power-domains.

Testing on the x1e80100 reference shows that both power-domains need to be
switched on for the GDSCs in the clock-controller to work. Some open
questions remain.

1. Should there be a hirearchy of power-domains in the clock-controller.
2. If there should be no hirearchy should the parent GDSC inside the
   clock-controller attach to each power-domain in the clock-controller.
3. If there are multiple parent GDSCs in a clock-controller do we attach
   those top-level GDSCs to each controller power-domain.
4. Finally should performance-states be applied equally across those
   power-domains.

It may be if we see more clock-controllers with multiple power-domains that
some mixture of these questions will need to be implemented for specific
hardware. Right now the approach taken here is to attach the
clock-controller GDSC parent to each clock-controller power-domain.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
 drivers/clk/qcom/common.c |  1 +
 drivers/clk/qcom/gdsc.c   | 35 +++++++++++++++++++++++++++++++++++
 drivers/clk/qcom/gdsc.h   |  1 +
 3 files changed, 37 insertions(+)

diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
index 7727295c57c8f6672d46d2380e1ff5ec2ac68d42..58a8397eefe51da237a4285d4e7cee967e19948f 100644
--- a/drivers/clk/qcom/common.c
+++ b/drivers/clk/qcom/common.c
@@ -338,6 +338,7 @@ int qcom_cc_really_probe(struct device *dev,
 		scd->dev = dev;
 		scd->scs = desc->gdscs;
 		scd->num = desc->num_gdscs;
+		scd->pd_list = cc->pd_list;
 		ret = gdsc_register(scd, &reset->rcdev, regmap);
 		if (ret)
 			return ret;
diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index 4fc6f957d0b846cc90e50ef243f23a7a27e66899..cb4afa6d584899f3dafa380d5e01be6de9711737 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -506,6 +506,36 @@ static int gdsc_init(struct gdsc *sc)
 	return ret;
 }
 
+static int gdsc_add_subdomain_list(struct dev_pm_domain_list *pd_list,
+				   struct generic_pm_domain *subdomain)
+{
+	int i, ret;
+
+	for (i = 0; i < pd_list->num_pds; i++) {
+		struct device *dev = pd_list->pd_devs[i];
+		struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);
+
+		ret = pm_genpd_add_subdomain(genpd, subdomain);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static void gdsc_remove_subdomain_list(struct dev_pm_domain_list *pd_list,
+				       struct generic_pm_domain *subdomain)
+{
+	int i;
+
+	for (i = 0; i < pd_list->num_pds; i++) {
+		struct device *dev = pd_list->pd_devs[i];
+		struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);
+
+		pm_genpd_remove_subdomain(genpd, subdomain);
+	}
+}
+
 int gdsc_register(struct gdsc_desc *desc,
 		  struct reset_controller_dev *rcdev, struct regmap *regmap)
 {
@@ -558,6 +588,9 @@ int gdsc_register(struct gdsc_desc *desc,
 			ret = pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
 		else if (!IS_ERR_OR_NULL(dev->pm_domain))
 			ret = pm_genpd_add_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
+		else if (desc->pd_list)
+			ret = gdsc_add_subdomain_list(desc->pd_list, &scs[i]->pd);
+
 		if (ret)
 			return ret;
 	}
@@ -580,6 +613,8 @@ void gdsc_unregister(struct gdsc_desc *desc)
 			pm_genpd_remove_subdomain(scs[i]->parent, &scs[i]->pd);
 		else if (!IS_ERR_OR_NULL(dev->pm_domain))
 			pm_genpd_remove_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
+		else if (desc->pd_list)
+			gdsc_remove_subdomain_list(desc->pd_list, &scs[i]->pd);
 	}
 	of_genpd_del_provider(dev->of_node);
 }
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index 1e2779b823d1c8ca077c9b4cd0a0dbdf5f9457ef..dd843e86c05b2f30e6d9e978681580016333839d 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -80,6 +80,7 @@ struct gdsc_desc {
 	struct device *dev;
 	struct gdsc **scs;
 	size_t num;
+	struct dev_pm_domain_list *pd_list;
 };
 
 #ifdef CONFIG_QCOM_GDSC

-- 
2.45.2