Subject: [RFC PATCH 04/10] devfreq: rk3399_dmc / rockchip: pm_domains: Register notify to DMC driver.

From: [email-masked] (Chanwoo Choi)
Date: Fri, 18 May 2018 11:44:20 +0900

Hi,

As I already commented[1], I think that it is not proper in order to pass
the devfreq instance to power_domain driver by separate defined function
(rockchip_pm_register_dmcfreq_notifier()).
[1] https://patchwork.kernel.org/patch/10349571/

Maybe, you could check the 'OF graph[1]' or 'device connection[2]'
for the device connection. Unfortunately, I'm not sure what is
best solution for this issue.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/graph.txt
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f2d9b66d84f3ff5ea3aff111e6a403e04fa8bf37

On 2018? 05? 15? 06:16, Enric Balletbo i Serra wrote:
> From: Lin Huang <[email-masked]>
> 
> The DMC (Dynamic Memory Interface) controller does a SiP call to the
> Trusted Firmware-A (TF-A) to change the DDR clock frequency. When this
> happens the TF-A writes to the PMU bus idle request register
> (PMU_BUS_IDLE_REQ) but at the same time it is possible that the Rockchip
> power domain driver writes to the same register. So, add a notification
> mechanism to ensure that the DMC and the PD driver does not access to this
> register at the same time.
> 
> Signed-off-by: Lin Huang <[email-masked]>
> [rewrite commit message]
> Signed-off-by: Enric Balletbo i Serra <[email-masked]>
> ---
> As I explained in the cover letter I have doubts regarding this patch
> but I did not find another way to do it. So I will appreciate any
> feedback on this.
> 
>  drivers/devfreq/rk3399_dmc.c      |  7 ++++++
>  drivers/soc/rockchip/pm_domains.c | 36 +++++++++++++++++++++++++++++++
>  include/soc/rockchip/rk3399_dmc.h | 14 ++++++++++++
>  3 files changed, 57 insertions(+)
>  create mode 100644 include/soc/rockchip/rk3399_dmc.h
> 
> diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
> index cc1bbca3fb15..2c4985a501cb 100644
> --- a/drivers/devfreq/rk3399_dmc.c
> +++ b/drivers/devfreq/rk3399_dmc.c
> @@ -28,6 +28,7 @@
>  #include <linux/rwsem.h>
>  #include <linux/suspend.h>
>  
> +#include <soc/rockchip/rk3399_dmc.h>
>  #include <soc/rockchip/rk3399_grf.h>
>  #include <soc/rockchip/rockchip_sip.h>
>  
> @@ -443,6 +444,12 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
>  	data->dev = dev;
>  	platform_set_drvdata(pdev, data);
>  
> +	rockchip_pm_register_dmcfreq_notifier(data->devfreq);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to register dmcfreq notifier\n");
> +		return ret;
> +	}
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/soc/rockchip/pm_domains.c b/drivers/soc/rockchip/pm_domains.c
> index 53efc386b1ad..b0e66f24b3e3 100644
> --- a/drivers/soc/rockchip/pm_domains.c
> +++ b/drivers/soc/rockchip/pm_domains.c
> @@ -8,6 +8,7 @@
>   * published by the Free Software Foundation.
>   */
>  
> +#include <linux/devfreq.h>
>  #include <linux/io.h>
>  #include <linux/iopoll.h>
>  #include <linux/err.h>
> @@ -76,9 +77,13 @@ struct rockchip_pmu {
>  	const struct rockchip_pmu_info *info;
>  	struct mutex mutex; /* mutex lock for pmu */
>  	struct genpd_onecell_data genpd_data;
> +	struct devfreq *devfreq;
> +	struct notifier_block dmc_nb;
>  	struct generic_pm_domain *domains[];
>  };
>  
> +static struct rockchip_pmu *dmc_pmu;
> +
>  #define to_rockchip_pd(gpd) container_of(gpd, struct rockchip_pm_domain, genpd)
>  
>  #define DOMAIN(pwr, status, req, idle, ack, wakeup)	\
> @@ -601,6 +606,35 @@ static int rockchip_pm_add_subdomain(struct rockchip_pmu *pmu,
>  	return error;
>  }
>  
> +static int rk3399_dmcfreq_notify(struct notifier_block *nb,
> +				 unsigned long event, void *data)
> +{
> +	if (event == DEVFREQ_PRECHANGE)
> +		mutex_lock(&dmc_pmu->mutex);
> +	else if (event == DEVFREQ_POSTCHANGE)
> +		mutex_unlock(&dmc_pmu->mutex);
> +
> +	return NOTIFY_OK;
> +}
> +
> +int rockchip_pm_register_dmcfreq_notifier(struct devfreq *devfreq)
> +{
> +	int ret;
> +
> +	if (!dmc_pmu)
> +		return -EPROBE_DEFER;
> +
> +	dmc_pmu->devfreq = devfreq;
> +	dmc_pmu->dmc_nb.notifier_call = rk3399_dmcfreq_notify;
> +	ret = devm_devfreq_register_notifier(devfreq->dev.parent,
> +					     dmc_pmu->devfreq,
> +					     &dmc_pmu->dmc_nb,
> +					     DEVFREQ_TRANSITION_NOTIFIER);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(rockchip_pm_register_dmcfreq_notifier);
> +
>  static int rockchip_pm_domain_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -694,6 +728,8 @@ static int rockchip_pm_domain_probe(struct platform_device *pdev)
>  		goto err_out;
>  	}
>  
> +	dmc_pmu = pmu;
> +
>  	return 0;
>  
>  err_out:
> diff --git a/include/soc/rockchip/rk3399_dmc.h b/include/soc/rockchip/rk3399_dmc.h
> new file mode 100644
> index 000000000000..031a62607f61
> --- /dev/null
> +++ b/include/soc/rockchip/rk3399_dmc.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2016-2018, Fuzhou Rockchip Electronics Co., Ltd
> + * Author: Lin Huang <[email-masked]>
> + */
> +
> +#ifndef __SOC_RK3399_DMC_H
> +#define __SOC_RK3399_DMC_H
> +
> +#include <linux/devfreq.h>
> +
> +int rockchip_pm_register_dmcfreq_notifier(struct devfreq *devfreq);
> +
> +#endif
> 

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics