Re: [PATCH v7 5/8] clk: qcom: gdsc: enable optional power domain support

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Sun 29 Aug 08:47 PDT 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.
> 
> Make gdsc code also use pm_runtime calls to ensure that registers are
> accessible during the gdsc_enable/gdsc_disable operations.
> 

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>  drivers/clk/qcom/gdsc.c | 51 ++++++++++++++++++++++++++++++++++++++---
>  drivers/clk/qcom/gdsc.h |  2 ++
>  2 files changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index 4ece326ea233..7e1dd8ccfa38 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 +51,22 @@ enum gdsc_status {
>  	GDSC_ON
>  };
>  
> +static int gdsc_pm_runtime_get(struct gdsc *sc)
> +{
> +	if (!sc->dev)
> +		return 0;
> +
> +	return pm_runtime_resume_and_get(sc->dev);
> +}
> +
> +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 +249,8 @@ 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 +306,22 @@ 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;
> +
> +	return _gdsc_enable(sc);
> +}
> +
> +static int _gdsc_disable(struct gdsc *sc)
> +{
> +	int ret;
> +
>  	if (sc->pwrsts == PWRSTS_ON)
>  		return gdsc_assert_reset(sc);
>  
> @@ -329,6 +356,18 @@ 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;
> +
> +	ret = _gdsc_disable(sc);
> +
> +	gdsc_pm_runtime_put(sc);
> +
> +	return ret;
> +}
> +
>  static int gdsc_init(struct gdsc *sc)
>  {
>  	u32 mask, val;
> @@ -443,6 +482,8 @@ 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]);
> @@ -457,6 +498,8 @@ 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);
> @@ -475,6 +518,8 @@ 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 {
> -- 
> 2.33.0
>