linux-kernel - Re: [PATCHv2 2/3] drm/imx: convey the pixelclk-active and de-active flags from DT to the ipu-di driver

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Message-ID: <1464172019.3545.50.camel@pengutronix.de>
Date:	Wed, 25 May 2016 12:26:59 +0200
From:	Philipp Zabel <p.zabel@...gutronix.de>
To:	Lothar Waßmann <LW@...O-electronics.de>
Cc:	David Airlie <airlied@...ux.ie>, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 2/3] drm/imx: convey the pixelclk-active and de-active
 flags from DT to the ipu-di driver

Am Mittwoch, den 25.05.2016, 08:11 +0200 schrieb Lothar Waßmann:
[...]
> > > @@ -81,10 +87,27 @@ static int imx_pd_connector_get_modes(struct drm_connector *connector)
> > >  
> > >  	if (np) {
> > >  		struct drm_display_mode *mode = drm_mode_create(connector->dev);
> > > +		struct videomode vm;
> > > +		int ret;
> > >  
> > >  		if (!mode)
> > >  			return -EINVAL;
> > > -		of_get_drm_display_mode(np, &imxpd->mode, OF_USE_NATIVE_MODE);
> > > +
> > > +		ret = of_get_videomode(np, &vm, OF_USE_NATIVE_MODE);
> > > +		if (ret)
> > > +			return ret;
> > > +		drm_display_mode_from_videomode(&vm, &imxpd->mode);
> > > +		drm_mode_debug_printmodeline(&imxpd->mode);
> > > +
> > > +		if (vm.flags & DISPLAY_FLAGS_PIXDATA_POSEDGE)
> > > +			imxpd->bus_flags |= DRM_BUS_FLAG_PIXDATA_POSEDGE;
> > > +		if (vm.flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
> > > +			imxpd->bus_flags |= DRM_BUS_FLAG_PIXDATA_NEGEDGE;
> > > +
> > > +		if (vm.flags & DISPLAY_FLAGS_DE_LOW)
> > > +			imxpd->bus_flags |= DRM_BUS_FLAG_DE_LOW;
> > > +		if (vm.flags & DISPLAY_FLAGS_DE_HIGH)
> > > +			imxpd->bus_flags |= DRM_BUS_FLAG_DE_HIGH;
> > 
> > This could be shared between ldb and parallel drivers if you extended
> > of_get_drm_display_mode to also return bus_flags, for example. The flags
> > translation could be put into a drm_bus_flags_from_videomode helper.
> > 
> I had that in mind also, but hesitated to change the generic
> of_get_drm_display_mode() to implement some i.MX specific functionality.

Since the videomode obtained from DT includes both the timing and pin
polarity information, and the drm way to express these are
drm_display_mode and bus_flags, respectively, there's nothing i.MX
specific about this.

regards
Philipp