linux-kernel - Re: [PATCH] drm/bridge: imx: imx8mp-hdmi-pai: enable pm runtime

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Message-ID: <CAA+D8AMkipi_iX=vagZMHXTNtqUqyFeVkU1Vr_wb4R82F1OHDA@mail.gmail.com>
Date: Fri, 30 Jan 2026 15:06:19 +0800
From: Shengjiu Wang <shengjiu.wang@...il.com>
To: Liu Ying <victor.liu@....com>
Cc: Shengjiu Wang <shengjiu.wang@....com>, andrzej.hajda@...el.com, 
	neil.armstrong@...aro.org, rfoss@...nel.org, 
	Laurent.pinchart@...asonboard.com, jonas@...boo.se, jernej.skrabec@...il.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, 
	airlied@...il.com, simona@...ll.ch, shawnguo@...nel.org, 
	s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com, 
	dri-devel@...ts.freedesktop.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: imx: imx8mp-hdmi-pai: enable pm runtime

On Fri, Jan 30, 2026 at 2:49 PM Liu Ying <victor.liu@....com> wrote:
>
> Hi Shengjiu,
>
> On Fri, Jan 30, 2026 at 01:55:08PM +0800, Shengjiu Wang wrote:
> > There is an audio channel shift issue with multi channel case, first run
> > the channel order is correct, but second run the channel order is shifted.
>
> Nit: I'd rephrase "There is an audio channel shift issue with multi channel
> case - the channel order is correct for the first run, but the channel order
> is shifted for the second run.".

Ok. will update.
>
> > The recovery method is to reset the pai interface.
>
> s/pai/PAI/

Ok.

>
> Can the channel order shift issue be fully fixed instead of implementing
> a "recovery method"?  I presume that this patch implements a recovery
> mechanism.  If it can't, any chip ERRATA?

Yes, it can be fully fixed by this patch. I will remove the "recovery" for
confusion.

>
> >
> > The reset can be handled by pm runtime, so add the pm runtime function.
>
> Nit: s/pm/PM/
>
> s/add the pm runtime function/enable PM runtime/

Ok.
>
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
> > ---
> >  drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pai.c | 15 +++++++++++++++
> >  1 file changed, 15 insertions(+)
>
> Subject prefix should be "drm/bridge: imx8mp-hdmi-pai:".
> Refer to what previous commits for i.MX bridge drivers use.

Ok.
>
> >
> > diff --git a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pai.c b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pai.c
> > index 8d13a35b206a..1afc729da9b9 100644
> > --- a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pai.c
> > +++ b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pai.c
> > @@ -8,6 +8,7 @@
> >  #include <linux/module.h>
> >  #include <linux/of_platform.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> >  #include <linux/regmap.h>
> >  #include <drm/bridge/dw_hdmi.h>
> >  #include <sound/asoundef.h>
> > @@ -33,6 +34,7 @@
> >
> >  struct imx8mp_hdmi_pai {
> >       struct regmap   *regmap;
> > +     struct device   *dev;
> >  };
> >
> >  static void imx8mp_hdmi_pai_enable(struct dw_hdmi *dw_hdmi, int channel,
> > @@ -43,6 +45,9 @@ static void imx8mp_hdmi_pai_enable(struct dw_hdmi *dw_hdmi, int channel,
> >       struct imx8mp_hdmi_pai *hdmi_pai = pdata->priv_audio;
> >       int val;
> >
> > +     if (pm_runtime_get_sync(hdmi_pai->dev) < 0)
>
> Use pm_runtime_resume_and_get instead.

Ok.
>
> -8<-
>   `int pm_runtime_get_sync(struct device *dev);`
>     - increment the device's usage counter, run pm_runtime_resume(dev) and
>       return its result;
>       note that it does not drop the device's usage counter on errors, so
>       consider using pm_runtime_resume_and_get() instead of it, especially
>       if its return value is checked by the caller, as this is likely to
>       result in cleaner code.
> -8<-
>
> > +             return;
> > +
> >       /* PAI set control extended */
> >       val =  WTMK_HIGH(3) | WTMK_LOW(3);
> >       val |= NUM_CH(channel);
> > @@ -85,6 +90,8 @@ static void imx8mp_hdmi_pai_disable(struct dw_hdmi *dw_hdmi)
> >
> >       /* Stop PAI */
> >       regmap_write(hdmi_pai->regmap, HTX_PAI_CTRL, 0);
> > +
> > +     pm_runtime_put_sync(hdmi_pai->dev);
> >  }
> >
> >  static const struct regmap_config imx8mp_hdmi_pai_regmap_config = {
> > @@ -101,6 +108,7 @@ static int imx8mp_hdmi_pai_bind(struct device *dev, struct device *master, void
> >       struct imx8mp_hdmi_pai *hdmi_pai;
> >       struct resource *res;
> >       void __iomem *base;
> > +     int ret;
> >
> >       hdmi_pai = devm_kzalloc(dev, sizeof(*hdmi_pai), GFP_KERNEL);
> >       if (!hdmi_pai)
> > @@ -121,6 +129,13 @@ static int imx8mp_hdmi_pai_bind(struct device *dev, struct device *master, void
> >       plat_data->disable_audio = imx8mp_hdmi_pai_disable;
> >       plat_data->priv_audio = hdmi_pai;
> >
> > +     hdmi_pai->dev = dev;
> > +     ret = devm_pm_runtime_enable(dev);
> > +     if (ret < 0) {
> > +             dev_err(dev, "failed to enable pm runtime: %d\n", ret);
>
> s/pm/PM/

Ok. will update them.

best regards
Shengjiu Wang

>
> > +             return ret;
> > +     }
> > +
> >       return 0;
> >  }
> >
>
> --
> Regards,
> Liu Ying
>