From 22d0be2a557e53a22feb484e8fce255fe09e6ad5 Mon Sep 17 00:00:00 2001 From: Jose Abreu Date: Mon, 17 Jul 2017 13:08:27 +0100 Subject: [PATCH] drm: arcpgu: Allow some clock deviation in crtc->mode_valid() callback Currently we expect that clock driver produces the exact same value as we are requiring. There can, and will, be some deviation however so we need to take that into account instead of just rejecting the mode. According to the HDMI spec we have a max of +-0.5% for the pixel clock frequency deviation. Lets take that into an advantage and use it to calculate how much deviation we can support. Signed-off-by: Jose Abreu Acked-by: Alexey Brodkin Cc: Carlos Palminha Cc: Alexey Brodkin Cc: Daniel Vetter Cc: Dave Airlie Signed-off-by: Alexey Brodkin --- drivers/gpu/drm/arc/arcpgu_crtc.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/arc/arcpgu_crtc.c b/drivers/gpu/drm/arc/arcpgu_crtc.c index 1859dd3ad622..55c5d5bd74e1 100644 --- a/drivers/gpu/drm/arc/arcpgu_crtc.c +++ b/drivers/gpu/drm/arc/arcpgu_crtc.c @@ -69,12 +69,13 @@ static enum drm_mode_status arc_pgu_crtc_mode_valid(struct drm_crtc *crtc, { struct arcpgu_drm_private *arcpgu = crtc_to_arcpgu_priv(crtc); long rate, clk_rate = mode->clock * 1000; + long diff = clk_rate / 200; /* +-0.5% allowed by HDMI spec */ rate = clk_round_rate(arcpgu->clk, clk_rate); - if (rate != clk_rate) - return MODE_NOCLOCK; + if ((max(rate, clk_rate) - min(rate, clk_rate) < diff) && (rate > 0)) + return MODE_OK; - return MODE_OK; + return MODE_NOCLOCK; } static void arc_pgu_crtc_mode_set_nofb(struct drm_crtc *crtc) -- 2.20.1