linux-kernel - [PATCH v4 06/15] drm/sun4i: Force the mixer rate at 150MHz

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Message-Id: <34f2c9d5c9ab48ead94253144a8e829cccfa4653.1512662253.git-series.maxime.ripard@free-electrons.com>
Date:   Thu,  7 Dec 2017 16:58:51 +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, plaes@...es.org,
        icenowy@...c.io,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        jernej.skrabec@...l.net, devicetree@...r.kernel.org,
        thierry.reding@...il.com
Subject: [PATCH v4 06/15] 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 |  9 +++++++++
 drivers/gpu/drm/sun4i/sun8i_mixer.h |  3 +++
 2 files changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c b/drivers/gpu/drm/sun4i/sun8i_mixer.c
index 29ceeb016d72..ff235e3228ce 100644
--- a/drivers/gpu/drm/sun4i/sun8i_mixer.c
+++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c
@@ -400,6 +400,14 @@ 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.
+	 */
+	if (mixer->cfg->mod_rate)
+		clk_set_rate(mixer->mod_clk, mixer->cfg->mod_rate);
+
 	list_add_tail(&mixer->engine.list, &drv->engine_list);
 
 	/* Reset the registers */
@@ -474,6 +482,7 @@ static const struct sun8i_mixer_cfg sun8i_v3s_mixer_cfg = {
 	.ui_num = 1,
 	.scaler_mask = 0x3,
 	.ccsc = 0,
+	.mod_rate = 150000000,
 };
 
 static const struct of_device_id sun8i_mixer_of_table[] = {
diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.h b/drivers/gpu/drm/sun4i/sun8i_mixer.h
index bc58040a88f9..f34e70c42adf 100644
--- a/drivers/gpu/drm/sun4i/sun8i_mixer.h
+++ b/drivers/gpu/drm/sun4i/sun8i_mixer.h
@@ -121,12 +121,15 @@ struct de2_fmt_info {
  *	Set value to 0 if this is first mixer or second mixer with VEP support.
  *	Set value to 1 if this is second mixer without VEP support. Other values
  *	are invalid.
+ * @mod_rate: module clock rate that needs to be set in order to have
+ *	a functional block.
  */
 struct sun8i_mixer_cfg {
 	int		vi_num;
 	int		ui_num;
 	int		scaler_mask;
 	int		ccsc;
+	unsigned long	mod_rate;
 };
 
 struct sun8i_mixer {
-- 
git-series 0.9.1