linux-kernel - [PATCH v2 05/18] drm/sun4i: Force the mixer rate at 150MHz

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Date:   Mon, 27 Nov 2017 16:41:29 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        plaes@...es.org, icenowy@...c.io,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        jernej.skrabec@...l.net
Subject: [PATCH v2 05/18] drm/sun4i: Force the mixer rate at 150MHz

It seems like the mixer can only run properly when clocked at 150MHz. In
order to have something more robust than simply a fire-and-forget
assigned-clocks-rate, let's put that in the code.

Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
---
 drivers/gpu/drm/sun4i/sun8i_mixer.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c b/drivers/gpu/drm/sun4i/sun8i_mixer.c
index cb193c5f1686..c0cdccf772a2 100644
--- a/drivers/gpu/drm/sun4i/sun8i_mixer.c
+++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c
@@ -315,6 +315,13 @@ static int sun8i_mixer_bind(struct device *dev, struct device *master,
 	}
 	clk_prepare_enable(mixer->mod_clk);
 
+	/*
+	 * It seems that we need to enforce that rate for whatever
+	 * reason for the mixer to be functional. Make sure it's the
+	 * case.
+	 */
+	clk_set_rate(mixer->mod_clk, 150000000);
+
 	list_add_tail(&mixer->engine.list, &drv->engine_list);
 
 	/* Reset the registers */
-- 
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