linux-kernel - RE: [PATCH 0/3] media: imx8mq-mipi-csi2: Simplify power management handling

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Message-ID:
 <AS8PR04MB9080AF5E451A74FA0C0B03C0FA762@AS8PR04MB9080.eurprd04.prod.outlook.com>
Date: Mon, 30 Sep 2024 07:51:45 +0000
From: "G.N. Zhou (OSS)" <guoniu.zhou@....nxp.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, "G.N. Zhou (OSS)"
	<guoniu.zhou@....nxp.com>
CC: "rmfrfs@...il.com" <rmfrfs@...il.com>, "martink@...teo.de"
	<martink@...teo.de>, "kernel@...i.sm" <kernel@...i.sm>, "mchehab@...nel.org"
	<mchehab@...nel.org>, "shawnguo@...nel.org" <shawnguo@...nel.org>,
	"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "kernel@...gutronix.de"
	<kernel@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>, "linux-media@...r.kernel.org"
	<linux-media@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 0/3] media: imx8mq-mipi-csi2: Simplify power management
 handling

Hi Laurent,

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Sent: Monday, September 30, 2024 3:22 PM
> To: G.N. Zhou (OSS) <guoniu.zhou@....nxp.com>
> Cc: rmfrfs@...il.com; martink@...teo.de; kernel@...i.sm;
> mchehab@...nel.org; shawnguo@...nel.org; s.hauer@...gutronix.de;
> kernel@...gutronix.de; festevam@...il.com; imx@...ts.linux.dev; linux-
> media@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH 0/3] media: imx8mq-mipi-csi2: Simplify power management
> handling
> 
> On Mon, Sep 30, 2024 at 07:08:09AM +0000, G.N. Zhou (OSS) wrote:
> > On Sunday, September 29, 2024 9:44 PM, Laurent Pinchart wrote:
> > >
> > > Hello,
> > >
> > > This small patch series is a reaction to "[PATCH] media: nxp:
> > > imx8mq-mipi-csi2: Fix CSI clocks always enabled issue" ([1]).
> > > Instead of making the PM handling more complex, I think it can be greatly
> simplified.
> > >
> > > I have only compile-tested the patches. Guoniu, could you give this a try ?
> >
> > After applying the patches and test both on iMX8ULP.
> >
> > For iMX8ULP, it will cause kernel dump when access CSI registers and
> > system hang during do suspend/resume while streaming Need to add
> > system suspend/resume handlers and call
> > pm_runtime_force_suspend/resume in the handlers.
> >
> > I tried to debug this issue and found pm runtime callback won't be
> > called when system resume. The state of power domain won't enabled.
> 
> Thank you for testing.
> 
> I wonder if this could be caused by the CSI bridge being resumed from system
> sleep before the CSI-2 receiver. Could you check if that's the case ? If so, does the
> following change fix the issue ?

I tested on iMX8ULP which don't use CSI bridge but ISI, not iMX8MQ. In ISI driver, I notice that
it already handler the device relationship when subdev bound like bellow:

link = device_link_add(isi->dev, sd->dev, DL_FLAG_STATELESS);
if (!link) {
        dev_err(isi->dev,
                "Failed to create device link to source %s\n", sd->name);
        return -EINVAL;
}

For iMX8MQ, I'm trying to enable it, but meet some problems, so can't give you the results in short time.

> 
> diff --git a/drivers/media/platform/nxp/imx7-media-csi.c
> b/drivers/media/platform/nxp/imx7-media-csi.c
> index 9566ff738818..c66b0621e395 100644
> --- a/drivers/media/platform/nxp/imx7-media-csi.c
> +++ b/drivers/media/platform/nxp/imx7-media-csi.c
> @@ -2057,9 +2057,22 @@ static int imx7_csi_notify_bound(struct
> v4l2_async_notifier *notifier,  {
>  	struct imx7_csi *csi = imx7_csi_notifier_to_dev(notifier);
>  	struct media_pad *sink = &csi->sd.entity.pads[IMX7_CSI_PAD_SINK];
> +	struct device_link *link;
> 
>  	csi->src_sd = sd;
> 
> +	/*
> +	 * Enforce suspend/resume ordering between the source (supplier) and
> +	 * the CSI (consumer). The source will be suspended before and resume
> +	 * after the CSI.
> +	 */
> +	link = device_link_add(csi->dev, sd->dev, DL_FLAG_STATELESS);
> +	if (!link) {
> +		dev_err(csi->dev,
> +			"Failed to create device link to source %s\n", sd->name);
> +		return -EINVAL;
> +	}
> +
>  	return v4l2_create_fwnode_links_to_pad(sd, sink,
> MEDIA_LNK_FL_ENABLED |
>  					       MEDIA_LNK_FL_IMMUTABLE);
>  }
> 
> > > [1]
> > > https://lore.kernel.org/r/20240929101635.1648234-1-guoniu.zhou@oss.n
> > > xp.com
> > >
> > > Laurent Pinchart (3):
> > >   media: imx8mq-mipi-csi2: Drop stream stop/restart at suspend/resume
> > >     time
> > >   media: imx8mq-mipi-csi2: Drop ST_SUSPENDED guard
> > >   media: imx8mq-mipi-csi2: Drop system suspend/resume handlers
> > >
> > >  drivers/media/platform/nxp/imx8mq-mipi-csi2.c | 113
> > > ++----------------
> > >  1 file changed, 10 insertions(+), 103 deletions(-)
> > >
> > >
> > > base-commit: 81ee62e8d09ee3c7107d11c8bbfd64073ab601ad
> 
> --
> Regards,
> 
> Laurent Pinchart