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Message-ID: <b91b00db-b3f1-418a-a686-b417b290eb4b@ideasonboard.com>
Date: Mon, 1 Dec 2025 14:40:01 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Swamil Jain <s-jain1@...com>
Cc: dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, devarsht@...com, praneeth@...com,
h-shenoy@...com, u-kumar1@...com, jyri.sarha@....fi, airlied@...il.com,
simona@...ll.ch, maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
tzimmermann@...e.de, robh@...nel.org, krzk+dt@...nel.org,
conor+dt@...nel.org, aradhya.bhatia@...ux.dev
Subject: Re: [PATCH v2 2/3] drm/tidss: Power up attached PM domains on probe
Hi,
On 25/11/2025 18:59, Swamil Jain wrote:
> From: Devarsh Thakkar <devarsht@...com>
>
> Some SoC's such as AM62P have dedicated power domains
> for OLDI which need to be powered on separately 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.
>
> Signed-off-by: Devarsh Thakkar <devarsht@...com>
> [j-choudhary@...com: fix PM call sequence causing kernel crash in OLDI]
> Signed-off-by: Jayesh Choudhary <j-choudhary@...com>
> Signed-off-by: Swamil Jain <s-jain1@...com>
> ---
> drivers/gpu/drm/tidss/tidss_drv.c | 88 +++++++++++++++++++++++++++++--
> drivers/gpu/drm/tidss/tidss_drv.h | 4 ++
> 2 files changed, 89 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/tidss/tidss_drv.c b/drivers/gpu/drm/tidss/tidss_drv.c
> index 1c8cc18bc53c..50158281715f 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 <linux/aperture.h>
>
> #include <drm/clients/drm_client_setup.h>
> @@ -107,6 +108,72 @@ 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);
There's IS_ERR_OR_NULL()
> + 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");
I don't think this print is needed. It would be printed on almost all
platforms with DSS.
> + 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;
> @@ -129,15 +196,24 @@ static int tidss_probe(struct platform_device *pdev)
>
> spin_lock_init(&tidss->irq_lock);
>
> + /* powering up associated OLDI domains */
I think the function name is self-explanatory, no comment needed.
> + ret = tidss_attach_pm_domains(tidss);
> + if (ret < 0) {
> + dev_err(dev, "failed to attach power domains %d\n", ret);
> + goto err_detach_pm_domains;
This is not correct. If tidss_attach_pm_domains() fails, it should do
its own cleanup, thus there's no need to goto err_detach_pm_domains.
> + }
> +
> ret = dispc_init(tidss);
> if (ret) {
> dev_err(dev, "failed to initialize dispc: %d\n", ret);
> - return ret;
> + goto err_detach_pm_domains;
> }
>
> ret = tidss_oldi_init(tidss);
> - if (ret)
> - return dev_err_probe(dev, ret, "failed to init OLDI\n");
> + if (ret) {
> + dev_dbg(dev, "failed to init OLDI: %d\n", ret);
> + goto err_oldi_deinit;
Same here, this is just not correct. Please go through the error
handling paths with your patch. This also changes dev_err_probe() to
dev_dbg().
> + }
>
> pm_runtime_enable(dev);
>
> @@ -203,8 +279,12 @@ static int tidss_probe(struct platform_device *pdev)
> pm_runtime_dont_use_autosuspend(dev);
> pm_runtime_disable(dev);
>
> +err_oldi_deinit:
> tidss_oldi_deinit(tidss);
>
> +err_detach_pm_domains:
> + tidss_detach_pm_domains(tidss);
> +
> return ret;
> }
>
> @@ -232,6 +312,8 @@ 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 e1c1f41d8b4b..6eb17cb32043 100644
> --- a/drivers/gpu/drm/tidss/tidss_drv.h
> +++ b/drivers/gpu/drm/tidss/tidss_drv.h
> @@ -41,6 +41,10 @@ struct tidss_device {
> /* protects the irq masks field and irqenable/irqstatus registers */
> spinlock_t irq_lock;
> dispc_irq_t irq_mask; /* enabled irqs */
> +
> + int num_domains; /* Handle attached PM domains */
What does the comment mean?
Tomi
> + struct device **pd_dev;
> + struct device_link **pd_link;
> };
>
> #define to_tidss(__dev) container_of(__dev, struct tidss_device, ddev)
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