[PATCH] drm: mxsfb_crtc: Fix the framebuffer misplacement

[Breno Matheus Lima]

2017-02-02 19:26 GMT-02:00 Fabio Estevam <festevam at gmail.com>:
>
> From: Fabio Estevam <fabio.estevam at nxp.com>
>
> Currently the framebuffer content is displayed with incorrect offsets
> in both the vertical and horizontal directions.
>
> The fbdev version of the driver does not show this problem. Breno Lima
> dumped the eLCDIF controller registers on both the drm and fbdev drivers
> and noticed that the VDCTRL3 register is configured incorrectly in the
> drm driver.
>
> The fbdev driver calculates the vertical and horizontal wait counts
> of the VDCTRL3 register by doing: back porch + sync length.
>
> Looking at the horizontal and vertical timing diagram from
> include/drm/drm_modes.h this value corresponds to:
>
> crtc_[hv]total - crtc_[hv]sync_start
>
> So fix the VDCTRL3 register setting accordingly so that the eLCDIF
> controller can properly show the framebuffer content in the correct
> position.
>
> Reported-by: Breno Lima <breno.lima at nxp.com>
> Signed-off-by: Fabio Estevam <fabio.estevam at nxp.com>
> ---
>  drivers/gpu/drm/mxsfb/mxsfb_crtc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> index e10a4ed..b56f86c 100644
> --- a/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> +++ b/drivers/gpu/drm/mxsfb/mxsfb_crtc.c
> @@ -184,8 +184,8 @@ static void mxsfb_crtc_mode_set_nofb(struct
mxsfb_drm_private *mxsfb)
>                VDCTRL2_SET_HSYNC_PERIOD(m->crtc_htotal),
>                mxsfb->base + LCDC_VDCTRL2);
>
> -       writel(SET_HOR_WAIT_CNT(m->crtc_hblank_end - m->crtc_hsync_end) |
> -             SET_VERT_WAIT_CNT(m->crtc_vblank_end - m->crtc_vsync_end),
> +       writel(SET_HOR_WAIT_CNT(m->crtc_htotal - m->crtc_hsync_start) |
> +              SET_VERT_WAIT_CNT(m->crtc_vtotal - m->crtc_vsync_start),
>                mxsfb->base + LCDC_VDCTRL3);
>
>         writel(SET_DOTCLK_H_VALID_DATA_CNT(m->hdisplay),
> --
> 2.7.4
>

Tested-by: Breno Lima <breno.lima at nxp.com>
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