OMAPDSS: DISPC: Fix 34xx overlay scaling calculation

commit 7faa92339bbb1e6b9a80983b206642517327eb75 OMAPDSS: DISPC: Handle
synclost errors in OMAP3 introduces limits check to prevent SYNCLOST errors
on OMAP3. However, it misses the logic found in Nokia kernels that is
needed to correctly calculate whether 3 tap or 5 tap rescaler to be used as
well as the logic to fallback to 3 taps if 5 taps clock results in too
tight horizontal timings. Without that patch "horizontal timing too tight"
errors are seen when a video with resolution above 640x350 is tried to be
played. The patch is a forward-ported logic found in Nokia N900 and N9/50
kernels.

Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index b05bf3fe364e2f97a5275552986c7238d58f7819..f51646f15cf2d4a6826c35f52d6f0f1074c6d898 100644 (file)
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -2001,7 +2001,8 @@ static void calc_tiler_rotation_offset(u16 screen_width, u16 width,
  */
 static int check_horiz_timing_omap3(unsigned long pclk, unsigned long lclk,
                const struct omap_video_timings *t, u16 pos_x,
-               u16 width, u16 height, u16 out_width, u16 out_height)
+               u16 width, u16 height, u16 out_width, u16 out_height,
+               bool five_taps)
 {
        const int ds = DIV_ROUND_UP(height, out_height);
        unsigned long nonactive;
@@ -2021,6 +2022,10 @@ static int check_horiz_timing_omap3(unsigned long pclk, unsigned long lclk,
        if (blank <= limits[i])
                return -EINVAL;
 
+       /* FIXME add checks for 3-tap filter once the limitations are known */
+       if (!five_taps)
+               return 0;
+
        /*
         * Pixel data should be prepared before visible display point starts.
         * So, atleast DS-2 lines must have already been fetched by DISPC
@@ -2196,22 +2201,30 @@ static int dispc_ovl_calc_scaling_34xx(unsigned long pclk, unsigned long lclk,
        do {
                in_height = DIV_ROUND_UP(height, *decim_y);
                in_width = DIV_ROUND_UP(width, *decim_x);
-               *core_clk = calc_core_clk_five_taps(pclk, mgr_timings,
-                       in_width, in_height, out_width, out_height, color_mode);
-
-               error = check_horiz_timing_omap3(pclk, lclk, mgr_timings,
-                               pos_x, in_width, in_height, out_width,
-                               out_height);
+               *five_taps = in_height > out_height;
 
                if (in_width > maxsinglelinewidth)
                        if (in_height > out_height &&
                                                in_height < out_height * 2)
                                *five_taps = false;
-               if (!*five_taps)
+again:
+               if (*five_taps)
+                       *core_clk = calc_core_clk_five_taps(pclk, mgr_timings,
+                                               in_width, in_height, out_width,
+                                               out_height, color_mode);
+               else
                        *core_clk = dispc.feat->calc_core_clk(pclk, in_width,
                                        in_height, out_width, out_height,
                                        mem_to_mem);
 
+               error = check_horiz_timing_omap3(pclk, lclk, mgr_timings,
+                               pos_x, in_width, in_height, out_width,
+                               out_height, *five_taps);
+               if (error && *five_taps) {
+                       *five_taps = false;
+                       goto again;
+               }
+
                error = (error || in_width > maxsinglelinewidth * 2 ||
                        (in_width > maxsinglelinewidth && *five_taps) ||
                        !*core_clk || *core_clk > dispc_core_clk_rate());
@@ -2228,7 +2241,7 @@ static int dispc_ovl_calc_scaling_34xx(unsigned long pclk, unsigned long lclk,
        } while (*decim_x <= *x_predecim && *decim_y <= *y_predecim && error);
 
        if (check_horiz_timing_omap3(pclk, lclk, mgr_timings, pos_x, width,
-                               height, out_width, out_height)){
+                               height, out_width, out_height, *five_taps)) {
                        DSSERR("horizontal timing too tight\n");
                        return -EINVAL;
        }