Commit 22d0be2a authored by Jose Abreu's avatar Jose Abreu Committed by Alexey Brodkin

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: default avatarJose Abreu <joabreu@synopsys.com>
Acked-by: default avatarAlexey Brodkin <abrodkin@synopsys.com>
Cc: Carlos Palminha <palminha@synopsys.com>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: default avatarAlexey Brodkin <abrodkin@synopsys.com>
parent 0c43ff59
...@@ -69,12 +69,13 @@ static enum drm_mode_status arc_pgu_crtc_mode_valid(struct drm_crtc *crtc, ...@@ -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); struct arcpgu_drm_private *arcpgu = crtc_to_arcpgu_priv(crtc);
long rate, clk_rate = mode->clock * 1000; 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); rate = clk_round_rate(arcpgu->clk, clk_rate);
if (rate != clk_rate) if ((max(rate, clk_rate) - min(rate, clk_rate) < diff) && (rate > 0))
return MODE_NOCLOCK; return MODE_OK;
return MODE_OK; return MODE_NOCLOCK;
} }
static void arc_pgu_crtc_mode_set_nofb(struct drm_crtc *crtc) static void arc_pgu_crtc_mode_set_nofb(struct drm_crtc *crtc)
......
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