From fff367c752f5fb998882c7bc0a213ab1e53857db Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Sat, 27 Oct 2012 15:50:28 +0200 Subject: [PATCH] drm/i915: clarify why we need to enable fdi plls so early For reference, see "Graphics BSpec: vol4g North Display Engine Registers [IVB], Display Mode Set Sequence", step 4 of the enabling sequence: a. "Enable PCH FDI Receiver PLL, wait for warmup plus DMI latency b. "Switch from Rawclk to PCDclk in FDI Receiver c. "Enable CPU FDI Transmitter PLL, wait for warmup" Cc: Paulo Zanoni Reviewed-by: Paulo Zanoni Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_display.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 54b1794..612b410 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -3227,6 +3227,9 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc) is_pch_port = ironlake_crtc_driving_pch(crtc); if (is_pch_port) { + /* Note: FDI PLL enabling _must_ be done before we enable the + * cpu pipes, hence this is separate from all the other fdi/pch + * enabling. */ ironlake_fdi_pll_enable(intel_crtc); } else { assert_fdi_tx_disabled(dev_priv, pipe); -- 2.7.4