Re: [Letux-kernel] [PATCH v16 1/4] drm/bridge: dw-hdmi: introduce dw_hdmi_enable_poll()

[Paul Cercueil]

Hi Nikolaus,

Le jeu., mars 3 2022 at 17:43:05 +0100, H. Nikolaus Schaller 
<hns@xxxxxxxxxxxxx> a écrit :
> Hi Neil,
>
> >  Am 03.03.2022 um 17:30 schrieb H. Nikolaus Schaller 
> > <hns@xxxxxxxxxxxxx>:
> >
> >  Hi Neil,
> >
> > >  Am 03.03.2022 um 17:23 schrieb Neil Armstrong 
> > > <narmstrong@xxxxxxxxxxxx>:
> > >
> > >  Hi,
> > >
> > >  On 26/02/2022 18:12, H. Nikolaus Schaller wrote:
> > > >  so that specialization drivers like ingenic-dw-hdmi can enable 
> > > > polling.
> > > >  Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>
> > > >  ---
> > > >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 9 +++++++++
> > > >  include/drm/bridge/dw_hdmi.h              | 1 +
> > > >  2 files changed, 10 insertions(+)
> > > >  diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c 
> > > > b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > > >  index 4befc104d2200..43e375da131e8 100644
> > > >  --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > > >  +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > > >  @@ -3217,6 +3217,15 @@ static int dw_hdmi_parse_dt(struct dw_hdmi 
> > > > *hdmi)
> > > >  	return 0;
> > > >  }
> > > >  +void dw_hdmi_enable_poll(struct dw_hdmi *hdmi, bool enable)
> > > >  +{
> > > >  +	if (hdmi->bridge.dev)
> > > >  +		hdmi->bridge.dev->mode_config.poll_enabled = enable;
> > > >  +	else
> > > >  +		dev_warn(hdmi->dev, "no hdmi->bridge.dev");
> > > >  +}
> > > >  +EXPORT_SYMBOL_GPL(dw_hdmi_enable_poll);
> > > >  +
> > > >  struct dw_hdmi *dw_hdmi_probe(struct platform_device *pdev,
> > > >  			      const struct dw_hdmi_plat_data *plat_data)
> > > >  {
> > > >  diff --git a/include/drm/bridge/dw_hdmi.h 
> > > > b/include/drm/bridge/dw_hdmi.h
> > > >  index 2a1f85f9a8a3f..963960794b40e 100644
> > > >  --- a/include/drm/bridge/dw_hdmi.h
> > > >  +++ b/include/drm/bridge/dw_hdmi.h
> > > >  @@ -196,5 +196,6 @@ enum drm_connector_status 
> > > > dw_hdmi_phy_read_hpd(struct dw_hdmi *hdmi,
> > > >  void dw_hdmi_phy_update_hpd(struct dw_hdmi *hdmi, void *data,
> > > >  			    bool force, bool disabled, bool rxsense);
> > > >  void dw_hdmi_phy_setup_hpd(struct dw_hdmi *hdmi, void *data);
> > > >  +void dw_hdmi_enable_poll(struct dw_hdmi *hdmi, bool enable);
> > > >    #endif /* __IMX_HDMI_H__ */
> > >
> > >  As I understand, this is because the IRQ line of the dw-hdmi IP 
> > > isn't connected right ? and you use the display-connector ddc gpio 
> > > instead ?
> >
> >  Yes. The IRQ line is not connected on all boards as far as I can 
> > see.
> >
> > >  In this case I think the Ingenic DRM core should call 
> > > drm_kms_helper_poll_init(drm) instead.
> >
> >  Ah, that is good. it seems to do "dw_hdmi_enable_poll()" in a more 
> > generic way.
>
> Well, I looked through source code and it is defined as
>
> 	void drm_kms_helper_poll_init(struct drm_device *dev)
>
> But there is no direct pointer to some drm_device available.
> Neither in dw-hdmi nor ingenic-dw-hdmi.

Well he said "the Ingenic DRM core" aka ingenic-drm-drv.c. You do have 
access to the main drm_device in the ingenic_drm_bind() function, so 
you can add it there (with a cleanup function calling 
drm_kms_helper_poll_fini() registered with drmm_add_action_or_reset()).

Cheers,
-Paul

> What should the parameter to drm_kms_helper_poll_init(drm) be?
>
> From comparing code to be able to set mode_config.poll_enabled = 
> enable it should be
>
> 	&hdmi->bridge.dev
>
> but the struct dw_hdmi *hdmi is an opaque type for the 
> ingenic-dw-hdmi driver.
> So it can't access the hdmi-bridge directly.
>
> What we can do is to make dw_hdmi_enable_poll() call 
> drm_kms_helper_poll_init()
> or drm_kms_helper_poll_fini().
>
> BR and thanks,
> Nikolaus