From: Eric Anholt <eric@anholt.net>
Date: Tue, 31 Oct 2017 12:32:57 -0700
Subject: drm/vc4: Skip ULPS latching when we're in that ULPS state already.
Git-commit: 1825067e2b49c984d4b1a77f3720a7ae2576d226
Patch-mainline: v4.18-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
It seems that trying to go from unlatched to unlatched will time out
waiting for STOP, and we can just skip that.
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20171031193258.17373-1-eric@anholt.net
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/vc4/vc4_dsi.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -753,6 +753,11 @@ static void vc4_dsi_ulps(struct vc4_dsi
(dsi->lanes > 2 ? DSI1_STAT_PHY_D2_STOP : 0) |
(dsi->lanes > 3 ? DSI1_STAT_PHY_D3_STOP : 0));
int ret;
+ bool ulps_currently_enabled = (DSI_PORT_READ(PHY_AFEC0) &
+ DSI_PORT_BIT(PHY_AFEC0_LATCH_ULPS));
+
+ if (ulps == ulps_currently_enabled)
+ return;
DSI_PORT_WRITE(STAT, stat_ulps);
DSI_PORT_WRITE(PHYC, DSI_PORT_READ(PHYC) | phyc_ulps);