Re: [linux-sunxi] [PATCH] video/modedb: fb_find_nearest_mode: take vmode into account

On 11 February 2013 14:52, Floris Bos [off-list ref] wrote:

On 02/11/2013 10:28 AM, Hans de Goede wrote:

quoted

On 02/10/2013 09:23 PM, Floris Bos wrote:

quoted

Previously fb_find_nearest_mode() only searched the modelist for a video
mode that best matches the
desired resolution and refresh rate.
With this patch it also takes the vmode into account if there is more
then one mode with the same
resolution and refresh rate.
Typical use case is HDMI TVs that support both 1080p60 and 1080i60

Signed-off-by: Floris Bos <redacted>
---
  drivers/video/modedb.c |    4 ++++
  1 file changed, 4 insertions(+)

diff --git a/drivers/video/modedb.c b/drivers/video/modedb.c
index a9a907c..e852371 100644
--- a/drivers/video/modedb.c
+++ b/drivers/video/modedb.c

@@ -913,6 +913,8 @@ const struct fb_videomode *fb_find_best_mode(const

struct fb_var_screeninfo *var
   * Finds best matching videomode, smaller or greater in dimension.
   * If more than 1 videomode is found, will return the videomode with
   * the closest refresh rate.
+ * If multiple modes with the same resolution and refresh rate are found
+ * pick the one with the matching vmode (e.g. non-interlaced)
   */
  const struct fb_videomode *fb_find_nearest_mode(const struct
fb_videomode *mode,
                              struct list_head *head)

@@ -939,6 +941,8 @@ const struct fb_videomode *fb_find_nearest_mode(const

struct fb_videomode *mode,
              if (diff_refresh > d) {
                  diff_refresh = d;
                  best = cmode;
+            } else if (diff_refresh = d && cmode->vmode = mode->vmode)
{
+                best = cmode;
              }
          }
      }

Hmm, my version of this patch was more conservative, only comparing the
INTERLACED bit
of vmode. I assume you've tested this, and it works as advertised? If so
ack.

It works as advertised on my HDMI TV.
fbcon_new_modelist() which uses fb_find_nearest_mode() no longer tries to
switch from 1080p to 1080i after hot-plugging the same HDMI TV.

But thinking of it, I wonder if it would be better to test on "vmode &
FB_VMODE_MASK" instead though.
So that it does tests on FB_VMODE_INTERLACED, FB_VMODE_DOUBLE and
FB_VMODE_ODD_FLD_FIRST
But not on FB_VMODE_YWRAP, FB_VMODE_SMOOTH_XPAN, FB_VMODE_CONUPDATE.

I don't have hardware with interlaced mode support so can't really test this.

I would expect that it would be better to just switch to flagless
modes when available and accept doublescan and interlaced when not.

eg. when you unplug an interlaced TV and plug in a progressive capable
TV the mode would be upgraded. Also when the old TV had 1080i50 and
the new has 1080i50 and 1080p60 I would pick the latter mode as user
unless in a very special situation.

Thanks

Michal