linux-kernel - [PATCH 4.17 250/324] amd/dc/dce100: On dce100, set clocks to 0 on suspend

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Message-Id: <20180823075008.562512221@linuxfoundation.org>
Date:   Thu, 23 Aug 2018 09:55:16 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Francis <David.Francis@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.17 250/324] amd/dc/dce100: On dce100, set clocks to 0 on suspend

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Francis <David.Francis@....com>

[ Upstream commit 8d4235f71513cdccd9dc52b674323c3591552bc1 ]

[Why]
When a dce100 asic was suspended, the clocks were not set to 0.
Upon resume, the new clock was compared to the existing clock,
they were found to be the same, and so the clock was not set.
This resulted in a pernicious blackscreen.

[How]
In atomic commit, check to see if there are any active pipes.
If no, set clocks to 0

Signed-off-by: David Francis <David.Francis@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/amd/display/dc/dce100/dce100_resource.c |   19 +++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/dce100/dce100_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/dce100/dce100_resource.c
@@ -678,9 +678,22 @@ bool dce100_validate_bandwidth(
 	struct dc  *dc,
 	struct dc_state *context)
 {
-	/* TODO implement when needed but for now hardcode max value*/
-	context->bw.dce.dispclk_khz = 681000;
-	context->bw.dce.yclk_khz = 250000 * MEMORY_TYPE_MULTIPLIER;
+	int i;
+	bool at_least_one_pipe = false;
+
+	for (i = 0; i < dc->res_pool->pipe_count; i++) {
+		if (context->res_ctx.pipe_ctx[i].stream)
+			at_least_one_pipe = true;
+	}
+
+	if (at_least_one_pipe) {
+		/* TODO implement when needed but for now hardcode max value*/
+		context->bw.dce.dispclk_khz = 681000;
+		context->bw.dce.yclk_khz = 250000 * MEMORY_TYPE_MULTIPLIER;
+	} else {
+		context->bw.dce.dispclk_khz = 0;
+		context->bw.dce.yclk_khz = 0;
+	}
 
 	return true;
 }