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

[Martin Kepplinger <martink@posteo.de>]

Am Montag, dem 30.09.2024 um 10:21 +0300 schrieb Laurent Pinchart:
> 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 ?
> 
> 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);
>  }


hi Laurent,

I now tested your 3 patches, initially including this extra change, on
the imx8mq Librem 5 and indeed streaming continues after system resume
now. It works without this extra change too, even though it seems to
make sense.

so for the 3-patch series at least:

Tested-by: Martin Kepplinger-Novaković <martink@posteo.de>

thanks. I seem to be able to drop a few patches now, but if anyone else
can test it too, please wait for that as well,

                              martin