From 7059e3d8d8f0d716f8a6664f365bcbef9d147905 Mon Sep 17 00:00:00 2001 From: Tomi Valkeinen Date: Fri, 10 Apr 2015 12:48:38 +0300 Subject: [PATCH] OMAPDSS: DISPC: do only y decimation on OMAP3 The current driver does both x and y decimation on OMAP3 DSS. Testing shows that x decimation rarely works, leading to underflows. The exact reason for this is unclear, as the underflows seem to happen even with low pixel clock rates, and I would presume that if the DSS can manage a display with 140MHz pixel clock, it could manage x decimation with factor 2 with a low pixel clock (~30MHz). So it is possible that there is a problem somewhere else, in memory management, or DSS DMA, or similar. I have not found anything that would help this. So, to fix the downscaling scaling, this patch removes x decimation for OMAP3. This will limit some of the more demanding downscaling scenarios, but one could argue that using DSS to downscale such a large amount is insane in the first place, as the produced image is rather bad quality. Signed-off-by: Tomi Valkeinen --- drivers/video/fbdev/omap2/dss/dispc.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/drivers/video/fbdev/omap2/dss/dispc.c b/drivers/video/fbdev/omap2/dss/dispc.c index 0bdb587cb48c..646d94a71a79 100644 --- a/drivers/video/fbdev/omap2/dss/dispc.c +++ b/drivers/video/fbdev/omap2/dss/dispc.c @@ -2300,7 +2300,6 @@ static int dispc_ovl_calc_scaling_34xx(unsigned long pclk, unsigned long lclk, { int error; u16 in_width, in_height; - int min_factor = min(*decim_x, *decim_y); const int maxsinglelinewidth = dss_feat_get_param_max(FEAT_PARAM_LINEWIDTH); @@ -2349,16 +2348,8 @@ again: } } - if (error) { - if (*decim_x == *decim_y) { - *decim_x = min_factor; - ++*decim_y; - } else { - swap(*decim_x, *decim_y); - if (*decim_x < *decim_y) - ++*decim_x; - } - } + if (error) + ++*decim_y; } while (*decim_x <= *x_predecim && *decim_y <= *y_predecim && error); if (error) { -- 2.20.1