From: Eric Anholt Date: Tue, 15 Aug 2017 23:47:19 +0000 (-0700) Subject: drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math. X-Git-Tag: v4.15-rc1~56^2~25^2~20 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=af2eca53206c59ce9308a4f5f46c4a104a179b6b;p=linux.git drm/vc4: Avoid using vrefresh==0 mode in DSI htotal math. The incoming mode might have a missing vrefresh field if it came from drmModeSetCrtc(), which the kernel is supposed to calculate using drm_mode_vrefresh(). We could either use that or the adjusted_mode's original vrefresh value. However, we can maintain a more exact vrefresh value (not just the integer approximation), by scaling by the ratio of our clocks. v2: Use math suggested by Andrzej Hajda instead. v3: Simplify math now that adjusted_mode->clock isn't padded. v4: Drop some parens. Signed-off-by: Eric Anholt Link: https://patchwork.freedesktop.org/patch/msgid/20170815234722.20700-2-eric@anholt.net Reviewed-by: Andrzej Hajda --- diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c index d1e0dc908048..04796d7d0fdb 100644 --- a/drivers/gpu/drm/vc4/vc4_dsi.c +++ b/drivers/gpu/drm/vc4/vc4_dsi.c @@ -866,7 +866,8 @@ static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder, adjusted_mode->clock = pixel_clock_hz / 1000 + 1; /* Given the new pixel clock, adjust HFP to keep vrefresh the same. */ - adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal); + adjusted_mode->htotal = adjusted_mode->clock * mode->htotal / + mode->clock; adjusted_mode->hsync_end += adjusted_mode->htotal - mode->htotal; adjusted_mode->hsync_start += adjusted_mode->htotal - mode->htotal;