Similarly to what is done for SKL, clear the dpll_hw_state of the pipe
config in hsw_dp_set_ddi_pll_sel(), since it main contain stale values.
That can happen if a crtc that was previously driving an HDMI connector
switches to a DP connector. In that case, the wrpll field was left with
its old value, leading to warnings like the one below:

[drm:check_crtc_state [i915]] *ERROR* mismatch in dpll_hw_state.wrpll (expected 
0xb035061f, found 0x00000000)
------------[ cut here ]------------
WARNING: CPU: 1 PID: 767 at drivers/gpu/drm/i915/intel_display.c:12324 
check_crtc_state+0x975/0x10b0 [i915]()
pipe state doesn't match!

This regression was indroduced in

commit dd3cd74acf12723045a64f1f2c6298ac7b34a5d5
Author: Ander Conselvan de Oliveira <>
Date:   Fri May 15 13:34:29 2015 +0300

    drm/i915: Don't overwrite (e)DP PLL selection on SKL

Signed-off-by: Ander Conselvan de Oliveira 

Only compile tested, for the wrpll warning.


 drivers/gpu/drm/i915/intel_dp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 4ebfc3a..fbd9ac3 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1147,6 +1147,9 @@ skl_edp_set_pll_config(struct intel_crtc_state 
*pipe_config, int link_clock)
 static void
 hsw_dp_set_ddi_pll_sel(struct intel_crtc_state *pipe_config, int link_bw)
+       memset(&pipe_config->dpll_hw_state, 0,
+              sizeof(pipe_config->dpll_hw_state));
        switch (link_bw) {
        case DP_LINK_BW_1_62:
                pipe_config->ddi_pll_sel = PORT_CLK_SEL_LCPLL_810;

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