OMAPDSS: DISPC: Fix calc_scaling_44xx() bugs for writeback pipeline

dispc_ovl_calc_scaling_44xx() doesn't work correctly for writeback. There are
two issues with it:

- the function tries to calculate pixel clock for the input plane using
  dispc_plane_pclk_rate(), calling this with writeback as input plane results in
  a BUG(), this function shouldn't be called for writeback at all. Fix this by
  calculating pixel clock only when we are not in mem to mem mode.

- the maximum input_width is the product of the downscale ratio supported and
  the and the given output_width. This was calculated incorrectly by dividing
  output_width with maxdownscale. Fix this.

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index bab9d6b95c32..36ecb91b2452 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -2264,14 +2264,16 @@ static int dispc_ovl_calc_scaling_44xx(enum omap_plane plane,
         u16 in_height = DIV_ROUND_UP(height, *decim_y);
         const int maxsinglelinewidth =
                                 dss_feat_get_param_max(FEAT_PARAM_LINEWIDTH);
-        unsigned long pclk = dispc_plane_pclk_rate(plane);
         const int maxdownscale = dss_feat_get_param_max(FEAT_PARAM_DOWNSCALE);
 
-        if (mem_to_mem)
-                in_width_max = DIV_ROUND_UP(out_width, maxdownscale);
-        else
+        if (mem_to_mem) {
+                in_width_max = out_width * maxdownscale;
+        } else {
+                unsigned long pclk = dispc_plane_pclk_rate(plane);
+
                 in_width_max = dispc_core_clk_rate() /
                                         DIV_ROUND_UP(pclk, out_width);
+        }
 
         *decim_x = DIV_ROUND_UP(width, in_width_max);