linux-kernel - Re: [PATCH v2] drm/bridge: cdns-dsi: Split pm_ops into runtime_pm and system

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Message-ID: <e319d432-8687-462d-9bce-660de01c6696@ideasonboard.com>
Date: Fri, 16 Jan 2026 13:57:08 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Abhash Kumar Jha <a-kumar2@...com>
Cc: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 Laurent.pinchart@...asonboard.com, jonas@...boo.se,
 jernej.skrabec@...il.com, s-jain1@...com, p-mantena@...com,
 aradhya.bhatia@...ux.dev, p.zabel@...gutronix.de, andrzej.hajda@...el.com,
 neil.armstrong@...aro.org, rfoss@...nel.org, mripard@...nel.org,
 tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch, devarsht@...com,
 u-kumar1@...com
Subject: Re: [PATCH v2] drm/bridge: cdns-dsi: Split pm_ops into runtime_pm and
 system_sleep ops

Hi,

On 12/01/2026 11:12, Abhash Kumar Jha wrote:
> If runtime-pm has already suspended the device and a system suspend
> occurs, then we see a kernel crash when disabling and unpreparing the
> clocks.
> 
> Use pm_runtime_force_suspend/resume in system_sleep pm callbacks to let
> runtime-pm take care of the coordination between system suspend and
> itself. This ensures that they do not interfere with each other.
> 
> Signed-off-by: Abhash Kumar Jha <a-kumar2@...com>
> ---
> Hi,
> 
> If a device is runtime_pm suspended and a system wide suspend is triggered,
> we see a kernel crash. Hence split the power management ops into separate
> system_sleep and runtime_pm ops.
> 
> Changes in v2:
> - Improve the commit description and subject.
> - Link to v1: https://lore.kernel.org/all/20260109060312.2853133-1-a-kumar2@ti.com/

See:

https://lore.kernel.org/all/20250512083215.436149-1-ivitro%40gmail.com/

I think that's a better fix.

 Tomi

> 
> Thanks,
> Abhash
> 
>  .../gpu/drm/bridge/cadence/cdns-dsi-core.c    | 32 +++++++++++++------
>  1 file changed, 23 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> index 09b289f0fcbf..25eaf0192013 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-dsi-core.c
> @@ -1230,7 +1230,18 @@ static const struct mipi_dsi_host_ops cdns_dsi_ops = {
>  	.transfer = cdns_dsi_transfer,
>  };
>  
> -static int __maybe_unused cdns_dsi_resume(struct device *dev)
> +static int cdns_dsi_runtime_suspend(struct device *dev)
> +{
> +	struct cdns_dsi *dsi = dev_get_drvdata(dev);
> +
> +	clk_disable_unprepare(dsi->dsi_sys_clk);
> +	clk_disable_unprepare(dsi->dsi_p_clk);
> +	reset_control_assert(dsi->dsi_p_rst);
> +
> +	return 0;
> +}
> +
> +static int cdns_dsi_runtime_resume(struct device *dev)
>  {
>  	struct cdns_dsi *dsi = dev_get_drvdata(dev);
>  
> @@ -1241,18 +1252,21 @@ static int __maybe_unused cdns_dsi_resume(struct device *dev)
>  	return 0;
>  }
>  
> -static int __maybe_unused cdns_dsi_suspend(struct device *dev)
> +static int cdns_dsi_suspend(struct device *dev)
>  {
> -	struct cdns_dsi *dsi = dev_get_drvdata(dev);
> +	return pm_runtime_force_suspend(dev);
> +}
>  
> -	clk_disable_unprepare(dsi->dsi_sys_clk);
> -	clk_disable_unprepare(dsi->dsi_p_clk);
> -	reset_control_assert(dsi->dsi_p_rst);
> -	return 0;
> +static int cdns_dsi_resume(struct device *dev)
> +{
> +	return pm_runtime_force_resume(dev);
>  }
>  
> -static UNIVERSAL_DEV_PM_OPS(cdns_dsi_pm_ops, cdns_dsi_suspend, cdns_dsi_resume,
> -			    NULL);
> +static const struct dev_pm_ops cdns_dsi_pm_ops = {
> +	SET_RUNTIME_PM_OPS(cdns_dsi_runtime_suspend,
> +			cdns_dsi_runtime_resume, NULL)
> +	SET_SYSTEM_SLEEP_PM_OPS(cdns_dsi_suspend, cdns_dsi_resume)
> +};
>  
>  static int cdns_dsi_drm_probe(struct platform_device *pdev)
>  {