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* [PATCH] rcar-csi2: Use standby mode instead of resetting
@ 2019-02-16 22:56 Niklas Söderlund
  2019-02-17 19:41 ` Jacopo Mondi
  2019-02-18  9:07 ` Geert Uytterhoeven
  0 siblings, 2 replies; 5+ messages in thread
From: Niklas Söderlund @ 2019-02-16 22:56 UTC (permalink / raw)
  To: Laurent Pinchart, linux-media; +Cc: linux-renesas-soc, Niklas Söderlund

Later versions of the datasheet updates the reset procedure to more
closely resemble the standby mode. Update the driver to enter and exit
the standby mode instead of resetting the hardware before and after
streaming is started and stopped.

While at it break out the full start and stop procedures from
rcsi2_s_stream() into the existing helper functions.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
 drivers/media/platform/rcar-vin/rcar-csi2.c | 69 +++++++++++++--------
 1 file changed, 42 insertions(+), 27 deletions(-)

diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
index f64528d2be3c95dd..f3099f3e536d808a 100644
--- a/drivers/media/platform/rcar-vin/rcar-csi2.c
+++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
@@ -14,6 +14,7 @@
 #include <linux/of_graph.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <linux/sys_soc.h>
 
 #include <media/v4l2-ctrls.h>
@@ -350,6 +351,7 @@ struct rcar_csi2 {
 	struct device *dev;
 	void __iomem *base;
 	const struct rcar_csi2_info *info;
+	struct reset_control *rstc;
 
 	struct v4l2_subdev subdev;
 	struct media_pad pads[NR_OF_RCAR_CSI2_PAD];
@@ -387,11 +389,19 @@ static void rcsi2_write(struct rcar_csi2 *priv, unsigned int reg, u32 data)
 	iowrite32(data, priv->base + reg);
 }
 
-static void rcsi2_reset(struct rcar_csi2 *priv)
+static void rcsi2_standby_mode(struct rcar_csi2 *priv, int on)
 {
-	rcsi2_write(priv, SRST_REG, SRST_SRST);
+	if (!on) {
+		pm_runtime_get_sync(priv->dev);
+		reset_control_deassert(priv->rstc);
+		return;
+	}
+
+	rcsi2_write(priv, PHYCNT_REG, 0);
+	rcsi2_write(priv, PHTC_REG, PHTC_TESTCLR);
+	reset_control_assert(priv->rstc);
 	usleep_range(100, 150);
-	rcsi2_write(priv, SRST_REG, 0);
+	pm_runtime_put(priv->dev);
 }
 
 static int rcsi2_wait_phy_start(struct rcar_csi2 *priv)
@@ -462,7 +472,7 @@ static int rcsi2_calc_mbps(struct rcar_csi2 *priv, unsigned int bpp)
 	return mbps;
 }
 
-static int rcsi2_start(struct rcar_csi2 *priv)
+static int rcsi2_start_receiver(struct rcar_csi2 *priv)
 {
 	const struct rcar_csi2_format *format;
 	u32 phycnt, vcdt = 0, vcdt2 = 0;
@@ -506,7 +516,6 @@ static int rcsi2_start(struct rcar_csi2 *priv)
 
 	/* Init */
 	rcsi2_write(priv, TREF_REG, TREF_TREF);
-	rcsi2_reset(priv);
 	rcsi2_write(priv, PHTC_REG, 0);
 
 	/* Configure */
@@ -564,19 +573,36 @@ static int rcsi2_start(struct rcar_csi2 *priv)
 	return 0;
 }
 
+static int rcsi2_start(struct rcar_csi2 *priv)
+{
+	int ret;
+
+	rcsi2_standby_mode(priv, 0);
+
+	ret = rcsi2_start_receiver(priv);
+	if (ret) {
+		rcsi2_standby_mode(priv, 1);
+		return ret;
+	}
+
+	ret = v4l2_subdev_call(priv->remote, video, s_stream, 1);
+	if (ret) {
+		rcsi2_standby_mode(priv, 1);
+		return ret;
+	}
+
+	return 0;
+}
+
 static void rcsi2_stop(struct rcar_csi2 *priv)
 {
-	rcsi2_write(priv, PHYCNT_REG, 0);
-
-	rcsi2_reset(priv);
-
-	rcsi2_write(priv, PHTC_REG, PHTC_TESTCLR);
+	v4l2_subdev_call(priv->remote, video, s_stream, 0);
+	rcsi2_standby_mode(priv, 1);
 }
 
 static int rcsi2_s_stream(struct v4l2_subdev *sd, int enable)
 {
 	struct rcar_csi2 *priv = sd_to_csi2(sd);
-	struct v4l2_subdev *nextsd;
 	int ret = 0;
 
 	mutex_lock(&priv->lock);
@@ -586,27 +612,12 @@ static int rcsi2_s_stream(struct v4l2_subdev *sd, int enable)
 		goto out;
 	}
 
-	nextsd = priv->remote;
-
 	if (enable && priv->stream_count == 0) {
-		pm_runtime_get_sync(priv->dev);
-
 		ret = rcsi2_start(priv);
-		if (ret) {
-			pm_runtime_put(priv->dev);
+		if (ret)
 			goto out;
-		}
-
-		ret = v4l2_subdev_call(nextsd, video, s_stream, 1);
-		if (ret) {
-			rcsi2_stop(priv);
-			pm_runtime_put(priv->dev);
-			goto out;
-		}
 	} else if (!enable && priv->stream_count == 1) {
 		rcsi2_stop(priv);
-		v4l2_subdev_call(nextsd, video, s_stream, 0);
-		pm_runtime_put(priv->dev);
 	}
 
 	priv->stream_count += enable ? 1 : -1;
@@ -936,6 +947,10 @@ static int rcsi2_probe_resources(struct rcar_csi2 *priv,
 	if (irq < 0)
 		return irq;
 
+	priv->rstc = devm_reset_control_get(&pdev->dev, NULL);
+	if (IS_ERR(priv->rstc))
+		return PTR_ERR(priv->rstc);
+
 	return 0;
 }
 
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2019-03-07  0:12 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-02-16 22:56 [PATCH] rcar-csi2: Use standby mode instead of resetting Niklas Söderlund
2019-02-17 19:41 ` Jacopo Mondi
2019-03-07  0:03   ` Niklas Söderlund
2019-02-18  9:07 ` Geert Uytterhoeven
2019-03-07  0:12   ` Niklas Söderlund

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