target/linux/brcm2708/patches-4.14/950-0203-drm-vc4-Skip-ULPS-latching-when-we-re-in-that-ULPS-s.patch

   1 From c86b5da9e8c4ca0fedd6cdbfc70cdc5f61b5d711 Mon Sep 17 00:00:00 2001
   2 From: Eric Anholt <eric@anholt.net>
   3 Date: Tue, 31 Oct 2017 11:33:10 -0700
   4 Subject: [PATCH 203/454] drm/vc4: Skip ULPS latching when we're in that ULPS
   5  state already.
   6
   7 It seems that trying to go from unlatched to unlatched will time out
   8 waiting for STOP, and we can just skip that.
   9
  10 Signed-off-by: Eric Anholt <eric@anholt.net>
  11 ---
  12  drivers/gpu/drm/vc4/vc4_dsi.c | 5 +++++
  13  1 file changed, 5 insertions(+)
  14
  15 --- a/drivers/gpu/drm/vc4/vc4_dsi.c
  16 +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
  17 @@ -753,6 +753,11 @@ static void vc4_dsi_ulps(struct vc4_dsi
  18                          (dsi->lanes > 2 ? DSI1_STAT_PHY_D2_STOP : 0) |
  19                          (dsi->lanes > 3 ? DSI1_STAT_PHY_D3_STOP : 0));
  20         int ret;
  21 +       bool ulps_currently_enabled = (DSI_PORT_READ(PHY_AFEC0) &
  22 +                                      DSI_PORT_BIT(PHY_AFEC0_LATCH_ULPS));
  23 +
  24 +       if (ulps == ulps_currently_enabled)
  25 +               return;
  26
  27         DSI_PORT_WRITE(STAT, stat_ulps);
  28         DSI_PORT_WRITE(PHYC, DSI_PORT_READ(PHYC) | phyc_ulps);