Re: [PATCH v4 3/6] clk: qcom: gdsc: enable optional power domain support

[Bjorn Andersson]

On Fri 09 Jul 20:32 CDT 2021, Dmitry Baryshkov wrote:

> On sm8250 dispcc and videocc registers are powered up by the MMCX power
> domain. Currently we use a regulator to enable this domain on demand,
> however this has some consequences, as genpd code is not reentrant.
> 
> Teach Qualcomm clock controller code about setting up runtime PM and
> using specified genpd for gdsc powerup. Clock core will use runtime_pm
> calls to ensure that clock registers are accessible. The genpd code will
> powerup the parent domain when gdsc is powered, thus ensuring that the
> power stays on. Make gdsc code also use pm_runtime calls to ensure that
> registers are accessible during the gdsc_enable/gdsc_disable operations.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
>  drivers/clk/qcom/common.c | 37 +++++++++++++++++----
>  drivers/clk/qcom/gdsc.c   | 67 +++++++++++++++++++++++++++++++++++++--
>  drivers/clk/qcom/gdsc.h   |  2 ++
>  3 files changed, 97 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
> index 60d2a78d1395..43d8f8feeb3c 100644
> --- a/drivers/clk/qcom/common.c
> +++ b/drivers/clk/qcom/common.c
> @@ -10,6 +10,7 @@
>  #include <linux/clk-provider.h>
>  #include <linux/reset-controller.h>
>  #include <linux/of.h>
> +#include <linux/pm_runtime.h>
>  
>  #include "common.h"
>  #include "clk-rcg.h"
> @@ -224,6 +225,11 @@ static struct clk_hw *qcom_cc_clk_hw_get(struct of_phandle_args *clkspec,
>  	return cc->rclks[idx] ? &cc->rclks[idx]->hw : NULL;
>  }
>  
> +static void qcom_cc_pm_runtime_disable(void *data)
> +{
> +	pm_runtime_disable(data);
> +}
> +
>  int qcom_cc_really_probe(struct platform_device *pdev,
>  			 const struct qcom_cc_desc *desc, struct regmap *regmap)
>  {
> @@ -241,6 +247,18 @@ int qcom_cc_really_probe(struct platform_device *pdev,
>  	if (!cc)
>  		return -ENOMEM;
>  
> +	pm_runtime_enable(dev);

As I said in v3, this will result in double pm_runtime_enable(), which
is not allowed. What I didn't remember is that we have 6 drivers that
rely on pm_runtime to keep their iface clock enabled during clock
operations, so it's not only isolated to the turingcc driver.

> +	ret = pm_runtime_get_sync(dev);

And I still think that you should add this to gdsc_init(), like you do
in gdsc_enable() and gdsc_disable.

Combined, there are no longer any changes to common.c


The rest of this looks good now!

Regards,
Bjorn

> +	if (ret < 0) {
> +		pm_runtime_put(dev);
> +		pm_runtime_disable(dev);
> +		return ret;
> +	}
> +
> +	ret = devm_add_action_or_reset(dev, qcom_cc_pm_runtime_disable, dev);
> +	if (ret)
> +		goto err;
> +
>  	reset = &cc->reset;
>  	reset->rcdev.of_node = dev->of_node;
>  	reset->rcdev.ops = &qcom_reset_ops;
> @@ -251,7 +269,7 @@ int qcom_cc_really_probe(struct platform_device *pdev,
>  
>  	ret = devm_reset_controller_register(dev, &reset->rcdev);
>  	if (ret)
> -		return ret;
> +		goto err;
>  
>  	if (desc->gdscs && desc->num_gdscs) {
>  		scd = devm_kzalloc(dev, sizeof(*scd), GFP_KERNEL);
> @@ -262,11 +280,11 @@ int qcom_cc_really_probe(struct platform_device *pdev,
>  		scd->num = desc->num_gdscs;
>  		ret = gdsc_register(scd, &reset->rcdev, regmap);
>  		if (ret)
> -			return ret;
> +			goto err;
>  		ret = devm_add_action_or_reset(dev, qcom_cc_gdsc_unregister,
>  					       scd);
>  		if (ret)
> -			return ret;
> +			goto err;
>  	}
>  
>  	cc->rclks = rclks;
> @@ -277,7 +295,7 @@ int qcom_cc_really_probe(struct platform_device *pdev,
>  	for (i = 0; i < num_clk_hws; i++) {
>  		ret = devm_clk_hw_register(dev, clk_hws[i]);
>  		if (ret)
> -			return ret;
> +			goto err;
>  	}
>  
>  	for (i = 0; i < num_clks; i++) {
> @@ -286,14 +304,21 @@ int qcom_cc_really_probe(struct platform_device *pdev,
>  
>  		ret = devm_clk_register_regmap(dev, rclks[i]);
>  		if (ret)
> -			return ret;
> +			goto err;
>  	}
>  
>  	ret = devm_of_clk_add_hw_provider(dev, qcom_cc_clk_hw_get, cc);
>  	if (ret)
> -		return ret;
> +		goto err;
> +
> +	pm_runtime_put(dev);
>  
>  	return 0;
> +
> +err:
> +	pm_runtime_put(dev);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(qcom_cc_really_probe);
>  
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index 51ed640e527b..cfe875f87efe 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->dev)
> +		return 0;
> +
> +	ret = pm_runtime_get_sync(sc->dev);
> +	if (ret < 0) {
> +		pm_runtime_put_noidle(sc->dev);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int gdsc_pm_runtime_put(struct gdsc *sc)
> +{
> +	if (!sc->dev)
> +		return 0;
> +
> +	return pm_runtime_put_sync(sc->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 +314,26 @@ 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);
> +
> +	gdsc_pm_runtime_put(sc);
> +
> +	return ret;
> +}
> +
> +static int _gdsc_disable(struct gdsc *sc)
> +{
> +	int ret;
> +
>  	if (sc->pwrsts == PWRSTS_ON)
>  		return gdsc_assert_reset(sc);
>  
> @@ -329,6 +368,22 @@ 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;
> +
> +	ret = gdsc_pm_runtime_get(sc);
> +	if (ret)
> +		return ret;
> +
> +	ret = _gdsc_disable(sc);
> +
> +	gdsc_pm_runtime_put(sc);
> +
> +	return ret;
> +}
> +
>  static int gdsc_init(struct gdsc *sc)
>  {
>  	u32 mask, val;
> @@ -425,6 +480,8 @@ int gdsc_register(struct gdsc_desc *desc,
>  	for (i = 0; i < num; i++) {
>  		if (!scs[i])
>  			continue;
> +		if (pm_runtime_enabled(dev))
> +			scs[i]->dev = dev;
>  		scs[i]->regmap = regmap;
>  		scs[i]->rcdev = rcdev;
>  		ret = gdsc_init(scs[i]);
> @@ -439,6 +496,8 @@ int gdsc_register(struct gdsc_desc *desc,
>  			continue;
>  		if (scs[i]->parent)
>  			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);
>  	}
>  
>  	return of_genpd_add_provider_onecell(dev->of_node, data);
> @@ -457,6 +516,8 @@ void gdsc_unregister(struct gdsc_desc *desc)
>  			continue;
>  		if (scs[i]->parent)
>  			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);
>  	}
>  	of_genpd_del_provider(dev->of_node);
>  }
> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
> index 5bb396b344d1..702d47a87af6 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
> + * @dev: the device holding the GDSC, used for pm_runtime calls
>   */
>  struct gdsc {
>  	struct generic_pm_domain	pd;
> @@ -58,6 +59,7 @@ struct gdsc {
>  
>  	const char 			*supply;
>  	struct regulator		*rsupply;
> +	struct device 			*dev;
>  };
>  
>  struct gdsc_desc {
> -- 
> 2.30.2
>