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drm: mxsfb: fix pixel clock polarity

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The DRM subsystem specifies the pixel clock polarity from a
controllers perspective: DRM_BUS_FLAG_PIXDATA_NEGEDGE means
the controller drives the data on pixel clocks falling edge.
That is the controllers DOTCLK_POL=0 (Default is data launched
at negative edge).

Also change the data enable logic to be high active by default
and only change if explicitly requested via bus_flags. With
that defaults are:
- Data enable: high active
- Pixel clock polarity: controller drives data on negative edge

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Stefan Agner 2016-12-14 12:48:09 -08:00 committed by Dave Airlie
parent 10f2889ba3
commit 53990e416b
1 changed files with 9 additions and 2 deletions
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11
drivers/gpu/drm/mxsfb/mxsfb_crtc.c
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@ -196,9 +196,16 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb)
vdctrl0 |= VDCTRL0_HSYNC_ACT_HIGH;
if (m->flags & DRM_MODE_FLAG_PVSYNC)
vdctrl0 |= VDCTRL0_VSYNC_ACT_HIGH;
if (bus_flags & DRM_BUS_FLAG_DE_HIGH)
/* Make sure Data Enable is high active by default */
if (!(bus_flags & DRM_BUS_FLAG_DE_LOW))
vdctrl0 |= VDCTRL0_ENABLE_ACT_HIGH;
if (bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE)
/*
* DRM_BUS_FLAG_PIXDATA_ defines are controller centric,
* controllers VDCTRL0_DOTCLK is display centric.
* Drive on positive edge -> display samples on falling edge
* DRM_BUS_FLAG_PIXDATA_POSEDGE -> VDCTRL0_DOTCLK_ACT_FALLING
*/
if (bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE)
vdctrl0 |= VDCTRL0_DOTCLK_ACT_FALLING;
writel(vdctrl0, mxsfb->base + LCDC_VDCTRL0);