Re: [EXT] Re: [PATCH v2 06/15] drm/mxsfb: Update mxsfb with additional pixel formats

From: Robert Chiras <robert.chiras@nxp.com>
To: "daniel@fooishbar.org" <daniel@fooishbar.org>
Cc: dl-linux-imx <linux-imx@nxp.com>, "marex@denx.de" <marex@denx.de>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"stefan@agner.ch" <stefan@agner.ch>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"agx@sigxcpu.org" <agx@sigxcpu.org>,
	"festevam@gmail.com" <festevam@gmail.com>,
	"daniel@ffwll.ch" <daniel@ffwll.ch>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"airlied@linux.ie" <airlied@linux.ie>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>
Subject: Re: [EXT] Re: [PATCH v2 06/15] drm/mxsfb: Update mxsfb with additional pixel formats
Date: Wed, 14 Aug 2019 14:58:47 +0000	[thread overview]
Message-ID: <1565794726.3209.77.camel@nxp.com> (raw)
In-Reply-To: <CAPj87rMFG=RGmfVnawbE7qX4zU7vdYxLJB__K4E3B8jcJ764KQ@mail.gmail.com>

Hi Daniel,

On Mi, 2019-08-14 at 12:44 +0100, Daniel Stone wrote:
> Hi Robert,
> 
> On Wed, 14 Aug 2019 at 11:49, Robert Chiras <robert.chiras@nxp.com>
> wrote:
> > 
> > +       case DRM_FORMAT_BGR565: /* BG16 */
> > +               if (mxsfb->devdata->ipversion < 4)
> > +                       goto err;
> > +               writel(CTRL2_ODD_LINE_PATTERN(CTRL2_LINE_PATTERN_BG
> > R) |
> > +                       CTRL2_EVEN_LINE_PATTERN(CTRL2_LINE_PATTERN_
> > BGR),
> > +                       mxsfb->base + LCDC_V4_CTRL2 + REG_SET);
> > +               /* Fall through */
> > +       case DRM_FORMAT_RGB565: /* RG16 */
> > +               ctrl |= CTRL_SET_WORD_LENGTH(0);
> > +               ctrl &= ~CTRL_DF16;
> > +               ctrl1 |= CTRL1_SET_BYTE_PACKAGING(0xf);
> > +               break;
> For non-BGR formats, do you need to write RGB line-pattern back to
> the
> CTRL2 register? Otherwise, if you start with BGR565 then switch back
> to RGB565, presumably CTRL2 would still be programmed for BGR so you
> would display inverted channels.
The LINE_PATTERN from LCDC_V4_CTRL2 register is cleared above, with
this code:
+       if (mxsfb->devdata->ipversion >= 4)
+               writel(CTRL2_ODD_LINE_PATTERN(CTRL2_LINE_PATTERN_CLR) |
+                      CTRL2_EVEN_LINE_PATTERN(CTRL2_LINE_PATTERN_CLR),
+                      mxsfb->base + LCDC_V4_CTRL2 + REG_CLR);
> 
> Same goes for all the other BGR/RGB format pairs below.
> 
> Cheers,
> Daniel

Thanks,
Robert