radeon: bug #1462, predownscale to make HD video work.

Use the overlay scaler's predownscale capability to make videos with large
horizontal resolution work if it exceeds the scaler buffer width. Make the
scaler buffer width user-configurable since we don't know it for all chips,
and using predownscaling may otherwise reduce quality even if it wouldn't
be needed. This should fix bug #1462.

1 files changed, 21 insertions, 19 deletions

diff --git a/src/radeon_video.c b/src/radeon_video.c
index b9b479f0..6a910a17 100644
--- a/src/radeon_video.c
+++ b/src/radeon_video.c
@@ -1364,17 +1364,6 @@ RADEONAllocAdaptor(ScrnInfoPtr pScrn)
         OUTPLL(pScrn, RADEON_VCLK_ECP_CNTL,
 	       (INPLL(pScrn, RADEON_VCLK_ECP_CNTL) | (1<<18)));
     }
-    
-    /* overlay scaler line length differs for different revisions 
-       this needs to be maintained by hand  */
-    switch(info->ChipFamily){
-    	case CHIP_FAMILY_R200:
-	case CHIP_FAMILY_R300:
-		pPriv->overlay_scaler_buffer_width=1920;
-		break;
-	default:
-		pPriv->overlay_scaler_buffer_width=1536;
-    	}
 
     /* Decide on tuner type */
     if((info->tunerType<0) && (info->MM_TABLE_valid)) {
@@ -2439,6 +2428,8 @@ RADEONDisplayVideo(
     CARD32 scale_cntl;
     double dsr;
     int tap_set;
+    int predownscale=0;
+    int src_w_d;
 
     is_rgb=0;
     switch(id){
@@ -2513,17 +2504,27 @@ RADEONDisplayVideo(
     step_by_y = 1;
     step_by_uv = step_by_y;
 
+    src_w_d = src_w;
+#if 0
+    /* XXX this does not appear to work */
     /* if the source width was larger than what would fit in overlay scaler increase step_by values */
     i=src_w;
-    while(i>pPriv->overlay_scaler_buffer_width){
-    	step_by_y++;
+    while(i>info->overlay_scaler_buffer_width){
+	step_by_y++;
 	step_by_uv++;
 	h_inc >>=1;
 	i=i/2;
-    	}
-
+	}
+#else
+    /* predownscale instead (yes this hurts quality) - will only work for widths up
+       to 2 times the overlay_scaler_buffer_width, should be enough */
+    if (src_w_d > info->overlay_scaler_buffer_width) {
+	src_w_d /= 2; /* odd widths? */
+	predownscale = 1;
+    }
+#endif
 
-    h_inc_d = src_w;
+    h_inc_d = src_w_d;
     h_inc_d = h_inc_d/drw_w;
     /* we could do a tad better  - but why
        bother when this concerns downscaling and the code is so much more
@@ -2540,7 +2541,7 @@ RADEONDisplayVideo(
     h_inc_uv = h_inc>>(step_by_uv-step_by_y);
     h_inc = h_inc * h_inc_d;
     h_inc_uv = h_inc_uv * h_inc_d;
-    /* pPriv->overlay_scaler_buffer_width is magic number - maximum line length the overlay scaler can fit 
+    /* info->overlay_scaler_buffer_width is magic number - maximum line length the overlay scaler can fit 
        in the buffer for 2 tap filtering */
     /* the only place it is documented in is in ATI source code */
     /* we need twice as much space for 4 tap filtering.. */
@@ -2550,7 +2551,7 @@ RADEONDisplayVideo(
 #if 0
     if(!is_rgb && (step_by_y==1) && (step_by_uv==1) && (h_inc < (1<<12))
        && (deinterlacing_method!=METHOD_WEAVE)
-       && (drw_w*2 <= pPriv->overlay_scaler_buffer_width)){
+       && (drw_w*2 <= info->overlay_scaler_buffer_width)){
         step_by_y=0;
         step_by_uv=1;
         h_inc_uv = h_inc;
@@ -2592,7 +2593,8 @@ RADEONDisplayVideo(
 
     RADEONWaitForFifo(pScrn, 10);
     OUTREG(RADEON_OV0_H_INC, h_inc | ((h_inc_uv >> 1) << 16));
-    OUTREG(RADEON_OV0_STEP_BY, step_by_y | (step_by_uv << 8));
+    OUTREG(RADEON_OV0_STEP_BY, step_by_y | (step_by_uv << 8) |
+	predownscale << 4 | predownscale << 12);
 
     x_off = 8;
     y_off = 0;