[PATCH] media: nxp: imx8mq-mipi-csi2: Fix CSI clocks always enabled issue

[G.N. Zhou (OSS)]

Hi Laurent,

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Sent: Sunday, September 29, 2024 8:01 PM
> To: G.N. Zhou (OSS) <guoniu.zhou at oss.nxp.com>
> Cc: rmfrfs at gmail.com; martink at posteo.de; kernel at puri.sm;
> mchehab at kernel.org; shawnguo at kernel.org; s.hauer at pengutronix.de;
> kernel at pengutronix.de; festevam at gmail.com; imx at lists.linux.dev; linux-
> media at vger.kernel.org; linux-arm-kernel at lists.infradead.org; linux-
> kernel at vger.kernel.org
> Subject: Re: [PATCH] media: nxp: imx8mq-mipi-csi2: Fix CSI clocks always enabled
> issue
> 
> Hi Guoniu,
> 
> Thank you for the patch.
> 
> On Sun, Sep 29, 2024 at 06:16:35PM +0800, guoniu.zhou at oss.nxp.com wrote:
> > From: "Guoniu.zhou" <guoniu.zhou at nxp.com>
> >
> > Fix CSI clocks always enabled issue after run system suspend/resume.
> >
> > The clocks for CSI will be enabled in imx8mq_mipi_csi_pm_resume() when
> > system resume and the state of CSI will be set to ST_POWERED.
> > It not only cause clock always enabled issue but also system hang
> > issue on iMX8ULP platform since imx8mq_mipi_csi_pm_suspend() will
> > access CSI registers if run system suspend/resume again, but the CSI
> > power domain is not active.
> >
> > In order to fix this issue, using pm_runtime_force_suspend/resume
> > instead of calling imx8mq_mipi_csi_pm_suspend/resume directly.
> 
> I think you can simplify suspend/resume handling in the driver by dropping the
> system suspend/resume handlers. At system suspend time the device should
> already be stopped, because the top-level driver (the CSI bridge in the i.MX8MQ)
> should have stopped the pipeline. Similarly, at system resume time, there should
> be no need to restart streaming, as the top-level driver will control that.
> 
> I'll send a patch and CC you, could you give it a try ?

Sure.

> 
> > Signed-off-by: Guoniu.zhou <guoniu.zhou at nxp.com>
> > ---
> >  drivers/media/platform/nxp/imx8mq-mipi-csi2.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> > b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> > index d4a6c5532969..15029bb81b35 100644
> > --- a/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> > +++ b/drivers/media/platform/nxp/imx8mq-mipi-csi2.c
> > @@ -697,8 +697,11 @@ static int imx8mq_mipi_csi_suspend(struct device
> > *dev)  {
> >  	struct v4l2_subdev *sd = dev_get_drvdata(dev);
> >  	struct csi_state *state = mipi_sd_to_csi2_state(sd);
> > +	int ret;
> >
> > -	imx8mq_mipi_csi_pm_suspend(dev);
> > +	ret = pm_runtime_force_suspend(dev);
> > +	if (ret < 0)
> > +		return ret;
> >
> >  	state->state |= ST_SUSPENDED;
> >
> > @@ -713,7 +716,7 @@ static int imx8mq_mipi_csi_resume(struct device *dev)
> >  	if (!(state->state & ST_SUSPENDED))
> >  		return 0;
> >
> > -	return imx8mq_mipi_csi_pm_resume(dev);
> > +	return pm_runtime_force_resume(dev);
> >  }
> >
> >  static int imx8mq_mipi_csi_runtime_suspend(struct device *dev)
> 
> --
> Regards,
> 
> Laurent Pinchart