From: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
The CSI can skip any out of up to 6 input frames, allowing to reduce the
frame rate at the output pads by small fractions.
Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
Signed-off-by: Steve Longerbeam <steve_longerbeam@xxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
---
drivers/staging/media/imx/imx-media-csi.c | 167 ++++++++++++++++++++++++++----
1 file changed, 146 insertions(+), 21 deletions(-)
diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index e26c025..ed3748a 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -2,6 +2,7 @@
* V4L2 Capture CSI Subdev for Freescale i.MX5/6 SOC
*
* Copyright (c) 2014-2017 Mentor Graphics Inc.
+ * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@xxxxxxxxxxxxxx>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -9,6 +10,7 @@
* (at your option) any later version.
*/
#include <linux/delay.h>
+#include <linux/gcd.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>
@@ -41,6 +43,18 @@
#define H_ALIGN 1 /* multiple of 2 lines */
#define S_ALIGN 1 /* multiple of 2 */
+/*
+ * struct csi_skip_desc - CSI frame skipping descriptor
+ * @keep - number of frames kept per max_ratio frames
+ * @max_ratio - width of skip_smfc, written to MAX_RATIO bitfield
+ * @skip_smfc - skip pattern written to the SKIP_SMFC bitfield
+ */
+struct csi_skip_desc {
+ u8 keep;
+ u8 max_ratio;
+ u8 skip_smfc;
+};
+
struct csi_priv {
struct device *dev;
struct ipu_soc *ipu;
@@ -64,8 +78,9 @@ struct csi_priv {
struct v4l2_mbus_framefmt format_mbus[CSI_NUM_PADS];
const struct imx_media_pixfmt *cc[CSI_NUM_PADS];
- struct v4l2_fract frame_interval;
+ struct v4l2_fract frame_interval[CSI_NUM_PADS];
struct v4l2_rect crop;
+ const struct csi_skip_desc *skip;
/* active vb2 buffers to send to video dev sink */
struct imx_media_buffer *active_vb2_buf[2];
@@ -581,6 +596,10 @@ static int csi_setup(struct csi_priv *priv)
ipu_csi_set_dest(priv->csi, priv->dest);
+ if (priv->dest == IPU_CSI_DEST_IDMAC)
+ ipu_csi_set_skip_smfc(priv->csi, priv->skip->skip_smfc,
+ priv->skip->max_ratio - 1, 0);
+
ipu_csi_dump(priv->csi);
return 0;
@@ -588,6 +607,7 @@ static int csi_setup(struct csi_priv *priv)
static int csi_start(struct csi_priv *priv)
{
+ struct v4l2_fract *output_fi, *input_fi;
u32 bad_frames = 0;
int ret;
@@ -596,10 +616,12 @@ static int csi_start(struct csi_priv *priv)
return -EINVAL;
}
+ output_fi = &priv->frame_interval[priv->active_output_pad];
+ input_fi = &priv->frame_interval[CSI_SINK_PAD];
+
ret = v4l2_subdev_call(priv->sensor->sd, sensor,
g_skip_frames, &bad_frames);
if (!ret && bad_frames) {
- struct v4l2_fract *fi = &priv->frame_interval;
u32 delay_usec;
/*
@@ -610,8 +632,8 @@ static int csi_start(struct csi_priv *priv)
* to lose vert/horiz sync.
*/
delay_usec = DIV_ROUND_UP_ULL(
- (u64)USEC_PER_SEC * fi->numerator * bad_frames,
- fi->denominator);
+ (u64)USEC_PER_SEC * input_fi->numerator * bad_frames,
+ input_fi->denominator);
usleep_range(delay_usec, delay_usec + 1000);
}
@@ -627,8 +649,7 @@ static int csi_start(struct csi_priv *priv)
/* start the frame interval monitor */
if (priv->fim && priv->dest == IPU_CSI_DEST_IDMAC)
- imx_media_fim_set_stream(priv->fim, &priv->frame_interval,
- true);
+ imx_media_fim_set_stream(priv->fim, output_fi, true);
ret = ipu_csi_enable(priv->csi);
if (ret) {
@@ -640,8 +661,7 @@ static int csi_start(struct csi_priv *priv)
fim_off:
if (priv->fim && priv->dest == IPU_CSI_DEST_IDMAC)
- imx_media_fim_set_stream(priv->fim, &priv->frame_interval,
- false);
+ imx_media_fim_set_stream(priv->fim, NULL, false);
idmac_stop:
if (priv->dest == IPU_CSI_DEST_IDMAC)
csi_idmac_stop(priv);
@@ -655,14 +675,85 @@ static void csi_stop(struct csi_priv *priv)
/* stop the frame interval monitor */
if (priv->fim)
- imx_media_fim_set_stream(priv->fim,
- &priv->frame_interval,
- false);
+ imx_media_fim_set_stream(priv->fim, NULL, false);
}
ipu_csi_disable(priv->csi);
}
+static const struct csi_skip_desc csi_skip[12] = {
+ { 1, 1, 0x00 }, /* Keep all frames */
+ { 5, 6, 0x10 }, /* Skip every sixth frame */
+ { 4, 5, 0x08 }, /* Skip every fifth frame */
+ { 3, 4, 0x04 }, /* Skip every fourth frame */
+ { 2, 3, 0x02 }, /* Skip every third frame */
+ { 3, 5, 0x0a }, /* Skip frames 1 and 3 of every 5 */
+ { 1, 2, 0x01 }, /* Skip every second frame */
+ { 2, 5, 0x0b }, /* Keep frames 1 and 4 of every 5 */
+ { 1, 3, 0x03 }, /* Keep one in three frames */
+ { 1, 4, 0x07 }, /* Keep one in four frames */
+ { 1, 5, 0x0f }, /* Keep one in five frames */
+ { 1, 6, 0x1f }, /* Keep one in six frames */
+};
+
+static void csi_apply_skip_interval(const struct csi_skip_desc *skip,
+ struct v4l2_fract *interval)
+{
+ unsigned int div;
+
+ interval->numerator *= skip->max_ratio;
+ interval->denominator *= skip->keep;
+
+ /* Reduce fraction to lowest terms */
+ div = gcd(interval->numerator, interval->denominator);
+ if (div > 1) {
+ interval->numerator /= div;
+ interval->denominator /= div;
+ }
+}
+
+/*
+ * Find the skip pattern to produce the output frame interval closest to the
+ * requested one, for the given input frame interval. Updates the output frame
+ * interval to the exact value.
+ */
+static const struct csi_skip_desc *csi_find_best_skip(struct v4l2_fract *in,
+ struct v4l2_fract *out)
+{
+ const struct csi_skip_desc *skip = &csi_skip[0], *best_skip = skip;
+ u32 min_err = UINT_MAX;
+ u64 want_us;
+ int i;
+
+ /* Default to 1:1 ratio */
+ if (out->numerator == 0 || out->denominator == 0 ||
+ in->numerator == 0 || in->denominator == 0) {
+ *out = *in;
+ return best_skip;
+ }
+
+ want_us = div_u64((u64)USEC_PER_SEC * out->numerator, out->denominator);
+
+ /* Find the reduction closest to the requested time per frame */
+ for (i = 0; i < ARRAY_SIZE(csi_skip); i++, skip++) {
+ u64 tmp, err;
+
+ tmp = div_u64((u64)USEC_PER_SEC * in->numerator *
+ skip->max_ratio, in->denominator * skip->keep);
+
+ err = abs((s64)tmp - want_us);
+ if (err < min_err) {
+ min_err = err;
+ best_skip = skip;
+ }
+ }
+
+ *out = *in;
+ csi_apply_skip_interval(best_skip, out);
+
+ return best_skip;
+}
+
/*
* V4L2 subdev operations.
*/
@@ -672,8 +763,13 @@ static int csi_g_frame_interval(struct v4l2_subdev *sd,
{
struct csi_priv *priv = v4l2_get_subdevdata(sd);
+ if (fi->pad >= CSI_NUM_PADS)
+ return -EINVAL;
+
mutex_lock(&priv->lock);
- fi->interval = priv->frame_interval;
+
+ fi->interval = priv->frame_interval[fi->pad];
+
mutex_unlock(&priv->lock);
return 0;
@@ -683,18 +779,44 @@ static int csi_s_frame_interval(struct v4l2_subdev *sd,
struct v4l2_subdev_frame_interval *fi)
{
struct csi_priv *priv = v4l2_get_subdevdata(sd);
+ struct v4l2_fract *input_fi;
+ int ret = 0;
mutex_lock(&priv->lock);
- /* Output pads mirror active input pad, no limits on input pads */
- if (fi->pad == CSI_SRC_PAD_IDMAC || fi->pad == CSI_SRC_PAD_DIRECT)
- fi->interval = priv->frame_interval;
+ input_fi = &priv->frame_interval[CSI_SINK_PAD];
- priv->frame_interval = fi->interval;
+ switch (fi->pad) {
+ case CSI_SINK_PAD:
+ /* No limits on input frame interval */
+ /* Reset output intervals and frame skipping ratio to 1:1 */
+ priv->frame_interval[CSI_SRC_PAD_IDMAC] = fi->interval;
+ priv->frame_interval[CSI_SRC_PAD_DIRECT] = fi->interval;
+ priv->skip = &csi_skip[0];
+ break;
+ case CSI_SRC_PAD_IDMAC:
+ /*
+ * frame interval at IDMAC output pad depends on input
+ * interval, modified by frame skipping.
+ */
+ priv->skip = csi_find_best_skip(input_fi, &fi->interval);
+ break;
+ case CSI_SRC_PAD_DIRECT:
+ /*
+ * frame interval at DIRECT output pad is same as input
+ * interval.
+ */
+ fi->interval = *input_fi;
+ break;
+ default:
+ ret = -EINVAL;
+ goto out;
+ }
+ priv->frame_interval[fi->pad] = fi->interval;
+out:
mutex_unlock(&priv->lock);
-
- return 0;
+ return ret;
}
static int csi_s_stream(struct v4l2_subdev *sd, int enable)
@@ -1358,11 +1480,14 @@ static int csi_registered(struct v4l2_subdev *sd)
&priv->cc[i]);
if (ret)
goto put_csi;
+
+ /* init default frame interval */
+ priv->frame_interval[i].numerator = 1;
+ priv->frame_interval[i].denominator = 30;
}
- /* init default frame interval */
- priv->frame_interval.numerator = 1;
- priv->frame_interval.denominator = 30;
+ /* disable frame skipping */
+ priv->skip = &csi_skip[0];
priv->fim = imx_media_fim_init(&priv->sd);
if (IS_ERR(priv->fim)) {
--
2.7.4
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