linux-kernel - Re: [PATCH] drm/tidss: Power up attached PM domains on probe

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Message-ID: <c9f17f9e-b9b5-9685-30ca-6a7d041dd8aa@ti.com>
Date:   Thu, 12 Oct 2023 17:10:06 +0530
From:   Devarsh Thakkar <devarsht@...com>
To:     <jyri.sarha@....fi>, <tomi.valkeinen@...asonboard.com>,
        <airlied@...il.com>, <daniel@...ll.ch>,
        <maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
        <tzimmermann@...e.de>, <dri-devel@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>
CC:     <praneeth@...com>, <nm@...com>, <vigneshr@...com>,
        <a-bhatia1@...com>, <j-luthra@...com>, <r-ravikumar@...com>,
        <j-choudhary@...com>
Subject: Re: [PATCH] drm/tidss: Power up attached PM domains on probe



On 09/10/23 13:20, Devarsh Thakkar wrote:
> Some SoC's such as AM62P have dedicated power domains
> for OLDI which need to be powered on separetely along
> with display controller.
> 
> So during driver probe, power up all attached PM domains
> enumerated in devicetree node for DSS.
> 
> This also prepares base to add display support for AM62P.
> 

NAK, for this patch, as discussed with team there are already plans
to have separate OLDI bridge driver which should eventually handle
the additional power domains.

Sorry for the noise.

Regards
Devarsh
> Signed-off-by: Devarsh Thakkar <devarsht@...com> > ---
>   drivers/gpu/drm/tidss/tidss_drv.c | 76 +++++++++++++++++++++++++++++++
>   drivers/gpu/drm/tidss/tidss_drv.h |  5 ++
>   2 files changed, 81 insertions(+)
> 
> diff --git a/drivers/gpu/drm/tidss/tidss_drv.c b/drivers/gpu/drm/tidss/tidss_drv.c
> index 4d063eb9cd0b..a703a27d17bf 100644
> --- a/drivers/gpu/drm/tidss/tidss_drv.c
> +++ b/drivers/gpu/drm/tidss/tidss_drv.c
> @@ -8,6 +8,7 @@
>   #include <linux/of.h>
>   #include <linux/module.h>
>   #include <linux/pm_runtime.h>
> +#include <linux/pm_domain.h>
>   
>   #include <drm/drm_atomic.h>
>   #include <drm/drm_atomic_helper.h>
> @@ -114,6 +115,72 @@ static const struct drm_driver tidss_driver = {
>   	.minor			= 0,
>   };
>   
> +static int tidss_detach_pm_domains(struct tidss_device *tidss)
> +{
> +	int i;
> +
> +	if (tidss->num_domains <= 1)
> +		return 0;
> +
> +	for (i = 0; i < tidss->num_domains; i++) {
> +		if (tidss->pd_link[i] && !IS_ERR(tidss->pd_link[i]))
> +			device_link_del(tidss->pd_link[i]);
> +		if (tidss->pd_dev[i] && !IS_ERR(tidss->pd_dev[i]))
> +			dev_pm_domain_detach(tidss->pd_dev[i], true);
> +		tidss->pd_dev[i] = NULL;
> +		tidss->pd_link[i] = NULL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int tidss_attach_pm_domains(struct tidss_device *tidss)
> +{
> +	struct device *dev = tidss->dev;
> +	int i;
> +	int ret;
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct device_node *np = pdev->dev.of_node;
> +
> +	tidss->num_domains = of_count_phandle_with_args(np, "power-domains",
> +							"#power-domain-cells");
> +	if (tidss->num_domains <= 1) {
> +		dev_dbg(dev, "One or less power domains, no need to do attach domains\n");
> +		return 0;
> +	}
> +
> +	tidss->pd_dev = devm_kmalloc_array(dev, tidss->num_domains,
> +					   sizeof(*tidss->pd_dev), GFP_KERNEL);
> +	if (!tidss->pd_dev)
> +		return -ENOMEM;
> +
> +	tidss->pd_link = devm_kmalloc_array(dev, tidss->num_domains,
> +					    sizeof(*tidss->pd_link), GFP_KERNEL);
> +	if (!tidss->pd_link)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < tidss->num_domains; i++) {
> +		tidss->pd_dev[i] = dev_pm_domain_attach_by_id(dev, i);
> +		if (IS_ERR(tidss->pd_dev[i])) {
> +			ret = PTR_ERR(tidss->pd_dev[i]);
> +			goto fail;
> +		}
> +
> +		tidss->pd_link[i] = device_link_add(dev, tidss->pd_dev[i],
> +						    DL_FLAG_STATELESS |
> +						    DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE);
> +		if (!tidss->pd_link[i]) {
> +			ret = -EINVAL;
> +			goto fail;
> +		}
> +	}
> +
> +	return 0;
> +fail:
> +	tidss_detach_pm_domains(tidss);
> +	return ret;
> +}
> +
>   static int tidss_probe(struct platform_device *pdev)
>   {
>   	struct device *dev = &pdev->dev;
> @@ -136,6 +203,13 @@ static int tidss_probe(struct platform_device *pdev)
>   
>   	platform_set_drvdata(pdev, tidss);
>   
> +	/* powering up associated OLDI domains */
> +	ret = tidss_attach_pm_domains(tidss);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to attach power domains %d\n", ret);
> +		return ret;
> +	}
> +
>   	ret = dispc_init(tidss);
>   	if (ret) {
>   		dev_err(dev, "failed to initialize dispc: %d\n", ret);
> @@ -193,6 +267,7 @@ static int tidss_probe(struct platform_device *pdev)
>   	dispc_runtime_suspend(tidss->dispc);
>   #endif
>   	pm_runtime_disable(dev);
> +	tidss_detach_pm_domains(tidss);
>   
>   	return ret;
>   }
> @@ -220,6 +295,7 @@ static void tidss_remove(struct platform_device *pdev)
>   	/* devm allocated dispc goes away with the dev so mark it NULL */
>   	dispc_remove(tidss);
>   
> +	tidss_detach_pm_domains(tidss);
>   	dev_dbg(dev, "%s done\n", __func__);
>   }
>   
> diff --git a/drivers/gpu/drm/tidss/tidss_drv.h b/drivers/gpu/drm/tidss/tidss_drv.h
> index d7f27b0b0315..3c8b37b3aba6 100644
> --- a/drivers/gpu/drm/tidss/tidss_drv.h
> +++ b/drivers/gpu/drm/tidss/tidss_drv.h
> @@ -31,6 +31,11 @@ struct tidss_device {
>   
>   	spinlock_t wait_lock;	/* protects the irq masks */
>   	dispc_irq_t irq_mask;	/* enabled irqs in addition to wait_list */
> +
> +	int num_domains; /* Handle attached PM domains */
> +	struct device **pd_dev;
> +	struct device_link **pd_link;
> +
>   };
>   
>   #define to_tidss(__dev) container_of(__dev, struct tidss_device, ddev)