On Fri, 2012-03-16 at 01:04 +0200, Ville Syrjälä wrote:

On Thu, Mar 15, 2012 at 05:18:52PM +0530, Chandrabhanu Mahapatra wrote:

quoted

In OMAP3 DISPC video overlays suffer from some undocumented horizontal position
and timing related limitations leading to SYNCLOST errors. Whenever the image
window is moved towards the right of the screen SYNCLOST errors become
frequent. Checks have been implemented to see that DISPC driver rejects
configuration exceeding above limitations.

This code was successfully tested on OMAP3. This code is written based on code
written by Ville Syrjälä [off-list ref] in Linux OMAP kernel. Ville
Syrjälä [off-list ref] had added checks for video overlay horizontal
timing and DISPC horizontal blanking length limitations.

Signed-off-by: Chandrabhanu Mahapatra <redacted>
---
 drivers/video/omap2/dss/dispc.c |   67 +++++++++++++++++++++++++++++++++++++--
 1 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index 5a1963e..ebfa613 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c

@@ -1622,6 +1622,58 @@ static void calc_dma_rotation_offset(u8 rotation, bool mirror,
 	}
 }
 
+static int check_horiz_timing(enum omap_channel channel, u16 pos_x,
+		u16 width, u16 height, u16 out_width, u16 out_height)
+{
+	int DS = DIV_ROUND_UP(height, out_height);
+	struct omap_dss_device *dssdev = dispc_mgr_get_device(channel);
+	struct omap_video_timings t = dssdev->panel.timings;
+	int pcd = REG_GET(DISPC_DIVISORo(channel), 7, 0);

pcd doesn't exist for TV out, which is the reason why you see
'lclk/pclk' ratio used instead in the harmattan kernel.

I'm surprised you still remember these things =). And even more
surprised that you actually bothered to review it, thanks for that.

Chandrabhanu, do you have an omap3 board with composite/svideo tv-out?
It'd be good to test on that also, as, like Ville points out, the above
code can't work for tv-out. Hmm, then again, it shouldn't work for HDMI
on OMAP4 either. Did you test with HDMI?

Or is the above code called for TV-manager at all? If not, perhaps it
could be named *_lcd or something. Or perhaps have a BUG_ON(channel !lcd1 or lcd2);

 Tomi