RE: [PATCH] drm: exynos: Fix fb_videomode <-> drm_mode_modeinfo conversion

Hi Laurent,

-----Original Message-----
From: Joonyoung Shim [mailto:jy0922.shim@samsung.com]
Sent: Thursday, March 08, 2012 10:06 PM
To: Laurent Pinchart
Cc: dri-devel@lists.freedesktop.org; linux-fbdev@vger.kernel.org; Inki

Dae;

Seung-Woo Kim; Kyungmin Park
Subject: Re: [PATCH] drm: exynos: Fix fb_videomode <-> drm_mode_modeinfo
conversion

On 03/08/2012 08:34 PM, Laurent Pinchart wrote:

quoted

The fb_videomode structure stores the front porch and back porch in the
right_margin and left_margin fields respectively. right_margin should
thus be computed with hsync_start - hdisplay, and left_margin with
htotal - hsync_end. The same holds for the vertical direction.

        Active               Front           Sync            Back
        Region               Porch                           Porch
<-------------------><----------------><-------------><---------------->

   //////////////////|
  ////////////////// |
//////////////////  |..................               ..................
                                        _______________

<------ xres -------><- right_margin -><- hsync_len -><- left_margin -->

<---- hdisplay ----->
<------------ hsync_start ------------>
<--------------------- hsync_end -------------------->
<--------------------------------- htotal ----------------------------->

Fix the fb_videomode<->  drm_mode_modeinfo conversion functions
accordingly.

Signed-off-by: Laurent Pinchart<laurent.pinchart@ideasonboard.com>
---
  drivers/gpu/drm/exynos/exynos_drm_connector.c |   16 ++++++++--------
  1 files changed, 8 insertions(+), 8 deletions(-)

While trying to understand how the fb_videomode and drm_mode_modeinfo

fields

quoted

map to each other, I found what might be a bug in the Exynos DRM driver.

Could

quoted

you please check and confirm that my understanding is correct ?

Good catch. You can refer Documentation/fb/framebuffer.txt to know in
detail.

Acked-by: Joonyoung Shim <redacted>

Thanks.

it seems like that you doesn't use latest exynos drm driver so I merged it
manually
for this, you can refer to this link:
http://git.infradead.org/users/kmpark/linux-samsung/shortlog/refs/heads/exyn
os-drm-fixes

Thanks,
Inki Dae

quoted

diff --git a/drivers/gpu/drm/exynos/exynos_drm_connector.c

b/drivers/gpu/drm/exynos/exynos_drm_connector.c

quoted

index d620b07..7bb1dca 100644

--- a/drivers/gpu/drm/exynos/exynos_drm_connector.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_connector.c

@@ -52,14 +52,14 @@ convert_to_display_mode(struct drm_display_mode

*mode,

quoted

  	mode->vrefresh = timing->refresh;

  	mode->hdisplay = timing->xres;
-	mode->hsync_start = mode->hdisplay + timing->left_margin;
+	mode->hsync_start = mode->hdisplay + timing->right_margin;
  	mode->hsync_end = mode->hsync_start + timing->hsync_len;
-	mode->htotal = mode->hsync_end + timing->right_margin;
+	mode->htotal = mode->hsync_end + timing->left_margin;

  	mode->vdisplay = timing->yres;
-	mode->vsync_start = mode->vdisplay + timing->upper_margin;
+	mode->vsync_start = mode->vdisplay + timing->lower_margin;
  	mode->vsync_end = mode->vsync_start + timing->vsync_len;
-	mode->vtotal = mode->vsync_end + timing->lower_margin;
+	mode->vtotal = mode->vsync_end + timing->upper_margin;

  	if (timing->vmode&  FB_VMODE_INTERLACED)
  		mode->flags |= DRM_MODE_FLAG_INTERLACE;

@@ -81,14 +81,14 @@ convert_to_video_timing(struct fb_videomode *timing,
  	timing->refresh = drm_mode_vrefresh(mode);

  	timing->xres = mode->hdisplay;
-	timing->left_margin = mode->hsync_start - mode->hdisplay;
+	timing->right_margin = mode->hsync_start - mode->hdisplay;
  	timing->hsync_len = mode->hsync_end - mode->hsync_start;
-	timing->right_margin = mode->htotal - mode->hsync_end;
+	timing->left_margin = mode->htotal - mode->hsync_end;

  	timing->yres = mode->vdisplay;
-	timing->upper_margin = mode->vsync_start - mode->vdisplay;
+	timing->lower_margin = mode->vsync_start - mode->vdisplay;
  	timing->vsync_len = mode->vsync_end - mode->vsync_start;
-	timing->lower_margin = mode->vtotal - mode->vsync_end;
+	timing->upper_margin = mode->vtotal - mode->vsync_end;

  	if (mode->flags&  DRM_MODE_FLAG_INTERLACE)
  		timing->vmode = FB_VMODE_INTERLACED;