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

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
map to each other, I found what might be a bug in the Exynos DRM driver. Could
you please check and confirm that my understanding is correct ?

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

-- 
Regards,

Laurent Pinchart

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

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

Hi Joonyoung,

On Thursday 08 March 2012 22:05:50 Joonyoung Shim wrote:

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

Thank you. There's a similar issue in exynos_mipi_dsi_set_display_mode() where 
front and back porch are inverted. I'll submit a patch for that as well.

-- 
Regards,

Laurent Pinchart

On Thu, Mar 08, 2012 at 04:31:51PM +0100, Laurent Pinchart wrote:

Hi Joonyoung,

On Thursday 08 March 2012 22:05:50 Joonyoung Shim wrote:

quoted

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

Thank you. There's a similar issue in exynos_mipi_dsi_set_display_mode() where 
front and back porch are inverted. I'll submit a patch for that as well.

Damned. This seems to be a common misunderstanding. I never really
thought about it and always assumed that 'front porch' and 'back porch'
refers to the picture and not to the sync signal. I was so sure that
I didn't even care to google it before I saw this patch.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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.

Wow I see this has remegered. Some time last year I posted a patch that 
had these routines in a generic format for people to use. I can repost 
them again if people are interested.

On Fri, Mar 9, 2012 at 12:57 AM, James Simmons [off-list ref] wrote:

Wow I see this has remegered. Some time last year I posted a patch that
had these routines in a generic format for people to use. I can repost
them again if people are interested.

Yes please!

-- 
When the facts change, I change my mind. What do you do, sir? ~ Keynes

Corbin Simpson
[off-list ref]

Hi James,

On Thursday 08 March 2012 16:57:21 James Simmons 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.

Wow I see this has remegered. Some time last year I posted a patch that
had these routines in a generic format for people to use. I can repost
them again if people are interested.

As part of the EDID parser rework, I will introduce a common structure to 
describe video modes. Conversion functions between the common structures and 
struct drm_mode_modeinfo, struct fb_videomode and struct v4l2_bt_timings will 
be provided. Direct conversion between drm_mode_modeinfo and fb_videomode 
should then disappear.

This being said, we could introduce add you conversion functions in the 
meantime. I will then post a patch to remove them when the common video mode 
structure will be pushed to mainline :-)

-- 
Regards,

Laurent Pinchart

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;