* [PATCH 3/3] media: vidtv: add initial debugfs interface
@ 2020-12-24 15:04 Daniel W. S. Almeida
2021-01-27 11:06 ` Mauro Carvalho Chehab
0 siblings, 1 reply; 3+ messages in thread
From: Daniel W. S. Almeida @ 2020-12-24 15:04 UTC (permalink / raw)
To: mchehab, Daniel W. S. Almeida
Cc: linux-media, linux-kernel-mentees, linux-kernel
From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
Add a debugfs interface for testing purposes that can be enabled
by selecting **DVB_VIDTV_DEBUGFS**. This makes it possible to:
dynamically inject errors at runtime by interacting with the files
at /sys/kernel/debug/vidtv/*
read some dvbv5 statistics from userspace more easily.
This is entirely optional and the driver will work without this option
selected.
Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
---
.../driver-api/media/drivers/vidtv.rst | 80 +++---
drivers/media/test-drivers/vidtv/Kconfig | 13 +
.../media/test-drivers/vidtv/vidtv_bridge.c | 13 +
.../media/test-drivers/vidtv/vidtv_bridge.h | 2 +
.../media/test-drivers/vidtv/vidtv_debugfs.h | 42 +++
drivers/media/test-drivers/vidtv/vidtv_mux.c | 272 ++++++++++++++++++
drivers/media/test-drivers/vidtv/vidtv_mux.h | 7 +
drivers/media/test-drivers/vidtv/vidtv_ts.c | 8 +
drivers/media/test-drivers/vidtv/vidtv_ts.h | 8 +
9 files changed, 412 insertions(+), 33 deletions(-)
create mode 100644 drivers/media/test-drivers/vidtv/vidtv_debugfs.h
diff --git a/Documentation/driver-api/media/drivers/vidtv.rst b/Documentation/driver-api/media/drivers/vidtv.rst
index 673bdff919ea..e7c450289774 100644
--- a/Documentation/driver-api/media/drivers/vidtv.rst
+++ b/Documentation/driver-api/media/drivers/vidtv.rst
@@ -227,6 +227,9 @@ vidtv_mux.[ch]
#. Delivering the resulting TS packets to the bridge
driver so it can pass them to the demux.
+vidtv_debugfs.h
+ Exposes data structures used in vidtv's debugfs interface.
+
Testing vidtv with v4l-utils
----------------------------
@@ -431,27 +434,53 @@ For more information on dvb-zap check its online documentation here:
See also: `zap <https://www.linuxtv.org/wiki/index.php/Zap>`_.
-What can still be improved in vidtv
------------------------------------
+Vidtv *debugfs* integration
+___________________________
+
+Vidtv now comes with a *debugfs* interface that can be enabled by selecting
+**DVB_VIDTV_DEBUGFS**. Using it, one can
+
+#. dynamically inject errors at runtime by interacting with the files at /sys/kernel/debug/vidtv/*
+
+#. read some dvbv5 statistics from userspace more easily
+
+.. note::
+ This is entirely optional and the driver will work without this option selected.
+
+At boot, vidtv will set up a directory per simulated frontend. Here is a list of
+created files and their associated functionality once they are written to:
+
+noise
+ The probability of adding random noise in the packets (0 - 10000).
+drop
+ Drop n packets at random
+shl
+ Shift left n bytes at random
+shr
+ Shift right n bytes at random
+discontinuity
+ Create n discontinuities at random. This means artificially increasing
+ the continuity counters such that a discontinuity error is generated.
+
+Another option is to provide a probability of such events ocurring. Drop, shl,
+shr, and discontinuity have versions that take in a probability in the [0,
+10000] range.
-Add *debugfs* integration
-~~~~~~~~~~~~~~~~~~~~~~~~~
+Writing to the files at the frontend directory will target all packets in the
+mux buffer. Alternatively, vidtv will also create a directory per PID. Writing
+to these files will, in turn, only affect that particular PID.
-Although frontend drivers provide DVBv5 statistics via the .read_status
-call, a nice addition would be to make additional statistics available to
-userspace via debugfs, which is a simple-to-use, RAM-based filesystem
-specifically designed for debug purposes.
-The logic for this would be implemented on a separate file so as not to
-pollute the frontend driver. These statistics are driver-specific and can
-be useful during tests.
+What can still be improved in vidtv
+-----------------------------------
+
+Improve debugfs support
+~~~~~~~~~~~~~~~~~~~~~~~
-The Siano driver is one example of a driver using
-debugfs to convey driver-specific statistics to userspace and it can be
-used as a reference.
+Vidtv offers support for dynamically injecting errors and retrieving some dvbv5
+stats via *debugfs*. This can be improved upon to add new ways of testing from
+userspace.
-This should be further enabled and disabled via a Kconfig
-option for convenience.
Add a way to test video
~~~~~~~~~~~~~~~~~~~~~~~
@@ -468,23 +497,6 @@ which resides at::
drivers/media/common/v4l2-tpg/
-Add white noise simulation
-~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-The vidtv tuner already has code to identify whether the chosen frequency
-is too far away from a table of valid frequencies. For now, this means that
-the demodulator can eventually lose the lock on the signal, since the tuner will
-report a bad signal quality.
-
-A nice addition is to simulate some noise when the signal quality is bad by:
-
-- Randomly dropping some TS packets. This will trigger a continuity error if the
- continuity counter is updated but the packet is not passed on to the demux.
-
-- Updating the error statistics accordingly (e.g. BER, etc).
-
-- Simulating some noise in the encoded data.
-
Functions and structs used within vidtv
---------------------------------------
@@ -511,3 +523,5 @@ Functions and structs used within vidtv
.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_common.c
.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_tuner.c
+
+.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_debugfs.h
diff --git a/drivers/media/test-drivers/vidtv/Kconfig b/drivers/media/test-drivers/vidtv/Kconfig
index 22c4fd39461f..05513f1c67e1 100644
--- a/drivers/media/test-drivers/vidtv/Kconfig
+++ b/drivers/media/test-drivers/vidtv/Kconfig
@@ -8,4 +8,17 @@ config DVB_VIDTV
working on userspace applications.
+ When in doubt, say N.
+
+config DVB_VIDTV_DEBUGFS
+ bool "Enable debugfs for vidtv"
+ depends on DVB_VIDTV
+ depends on DEBUG_FS
+
+ help
+ Choose Y to enable the vidtv debugfs interface. Currently allows for
+ dynamically introducing errors in the generated MPEG Transport Stream
+ for testing purposes.
+
+
When in doubt, say N.
diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
index fc64d0c8492a..d5ebe680724f 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
@@ -10,6 +10,7 @@
* Copyright (C) 2020 Daniel W. S. Almeida
*/
+#include <linux/debugfs.h>
#include <linux/dev_printk.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
@@ -172,6 +173,7 @@ static int vidtv_start_streaming(struct vidtv_dvb *dvb)
.transport_stream_id = VIDTV_DEFAULT_TS_ID,
.network_id = VIDTV_DEFAULT_NETWORK_ID,
.network_name = VIDTV_DEFAULT_NETWORK_NAME,
+ .debugfs_root = dvb->debugfs_root,
.priv = dvb,
};
struct device *dev = &dvb->pdev->dev;
@@ -485,6 +487,7 @@ static int vidtv_bridge_dvb_init(struct vidtv_dvb *dvb)
static int vidtv_bridge_probe(struct platform_device *pdev)
{
struct vidtv_dvb *dvb;
+ struct dentry *debugfs_root;
int ret;
dvb = kzalloc(sizeof(*dvb), GFP_KERNEL);
@@ -501,6 +504,12 @@ static int vidtv_bridge_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, dvb);
+#ifdef CONFIG_DVB_VIDTV_DEBUGFS
+ debugfs_root = debugfs_create_dir("vidtv", NULL);
+ if (!IS_ERR(debugfs_root))
+ dvb->debugfs_root = debugfs_root;
+#endif //CONFIG_DVB_VIDTV_DEBUGFS
+
dev_info(&pdev->dev, "Successfully initialized vidtv!\n");
return ret;
@@ -516,6 +525,10 @@ static int vidtv_bridge_remove(struct platform_device *pdev)
dvb = platform_get_drvdata(pdev);
+#ifdef CONFIG_DVB_VIDTV_DEBUGFS
+ debugfs_remove_recursive(dvb->debugfs_root);
+#endif //CONFIG_DVB_VIDTV_DEBUGFS
+
mutex_destroy(&dvb->feed_lock);
for (i = 0; i < NUM_FE; ++i) {
diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.h b/drivers/media/test-drivers/vidtv/vidtv_bridge.h
index 2528adaee27d..9ef37d8ad2cc 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_bridge.h
+++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.h
@@ -42,6 +42,7 @@
* @feed_lock: Protects access to the start/stop stream logic/data.
* @streaming: Whether we are streaming now.
* @mux: The abstraction responsible for delivering MPEG TS packets to the bridge.
+ * @debugfs_root: A handle to vidtv's debugfs directory
*/
struct vidtv_dvb {
struct platform_device *pdev;
@@ -60,6 +61,7 @@ struct vidtv_dvb {
bool streaming;
struct vidtv_mux *mux;
+ struct dentry *debugfs_root;
};
#endif // VIDTV_BRIDG_H
diff --git a/drivers/media/test-drivers/vidtv/vidtv_debugfs.h b/drivers/media/test-drivers/vidtv/vidtv_debugfs.h
new file mode 100644
index 000000000000..1743fe6d96cf
--- /dev/null
+++ b/drivers/media/test-drivers/vidtv/vidtv_debugfs.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Vidtv serves as a reference DVB driver and helps validate the existing APIs
+ * in the media subsystem. It can also aid developers working on userspace
+ * applications.
+ *
+ * Copyright (C) 2020 Daniel W. S. Almeida
+ */
+
+#ifndef VIDTV_DEBUGFS_H
+#define VIDTV_DEBUGFS_H
+#include <linux/debugfs.h>
+
+/**
+ * struct vidtv_debugfs - Represents the vidtv debugfs interface
+ *
+ * @dir_dentry: A handle to the debugfs dentry
+ * @noise: Probability of adding noise to a byte in a packet [0, 10000]
+ * @drop: Drop n packets at random.
+ * @drop_probability: Probability to randomly drop a packet [0, 10000]
+ * @shl_probability: Probability to randomly shift left a byte in a packet [0, 10000]
+ * @shr_probability: Probability to randomly shift right a byte in a packet [0, 10000]
+ * @discontinuity_probability: Probability of artificially creating a
+ * discontinuity error [0, 10000]
+ * @shl: Shift n bytes left at random, i.e. byte[i] = byte[i] << 1;
+ * @shr: Shift n bytes right at random, i.e. byte[i] = byte[i] >>1;
+ * @discontinuity: Create n discontinuity errors
+ */
+struct vidtv_debugfs {
+ struct dentry *dir_dentry;
+ u32 noise;
+ u32 drop_probability;
+ u32 shl_probability;
+ u32 shr_probability;
+ u32 discontinuity_probability;
+ u32 drop;
+ u32 shl;
+ u32 shr;
+ u32 discontinuity;
+};
+
+#endif //VIDTV_DEBUGFS_H
diff --git a/drivers/media/test-drivers/vidtv/vidtv_mux.c b/drivers/media/test-drivers/vidtv/vidtv_mux.c
index b51e6a3b8cbe..e6d69fe01908 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_mux.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_mux.c
@@ -12,11 +12,14 @@
* Copyright (C) 2020 Daniel W. S. Almeida
*/
+#include "vidtv_debugfs.h"
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/dev_printk.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/math64.h>
+#include <linux/random.h>
#include <linux/ratelimit.h>
#include <linux/slab.h>
#include <linux/types.h>
@@ -385,6 +388,204 @@ static void vidtv_mux_clear(struct vidtv_mux *m)
m->mux_buf_offset = 0;
}
+static void vidtv_mux_add_random_noise(struct vidtv_mux *m, u32 noise_prob, u32 pkt_start)
+{
+ u8 noise;
+ u8 *pkt = m->mux_buf + pkt_start;
+ u32 i;
+
+ for (i = 0; i < TS_PACKET_LEN; i++)
+ if (prandom_u32_max(10000) < noise_prob) {
+ noise = prandom_u32_max(0xff);
+ pkt[i] = pkt[i] + noise;
+ }
+}
+
+static void vidtv_mux_drop_random(struct vidtv_mux *m, u32 drop_prob, u32 pkt_start, u32 *nbytes)
+{
+ u8 *pkt = m->mux_buf + pkt_start;
+ u8 *last_pkt = m->mux_buf + m->mux_buf_offset - TS_PACKET_LEN;
+ u32 npkts = m->mux_buf_offset / 188;
+
+ if (!npkts)
+ return;
+
+ if (prandom_u32_max(10000) < drop_prob) {
+ if (npkts > 1 && pkt != last_pkt) {
+ //overwrite victim with last packet
+ memcpy(pkt, last_pkt, TS_PACKET_LEN);
+ //remove last packet from buffer
+ memset(last_pkt, 0, TS_PACKET_LEN);
+ } else {
+ //just erase it
+ memset(pkt, 0, TS_PACKET_LEN);
+ }
+
+ //keep track of the loss of this packet
+ m->mux_buf_offset -= TS_PACKET_LEN;
+ *nbytes -= TS_PACKET_LEN;
+ }
+}
+
+static void vidtv_mux_shl_random(struct vidtv_mux *m, u32 shl_prob, u32 pkt_start)
+{
+ u8 *pkt = m->mux_buf + pkt_start;
+ /* select one of the 188 bytes at random */
+ u8 *byte = pkt + prandom_u32_max(TS_PACKET_LEN);
+
+ if (prandom_u32_max(10000) < shl_prob)
+ *byte = *byte << 1;
+}
+
+static void vidtv_mux_shr_random(struct vidtv_mux *m, u32 shr_prob, u32 pkt_start)
+{
+ u8 *pkt = m->mux_buf + pkt_start;
+ /* select one of the 188 bytes at random */
+ u8 *byte = pkt + prandom_u32_max(TS_PACKET_LEN);
+
+ if (prandom_u32_max(10000) < shr_prob)
+ *byte = *byte >> 1;
+}
+
+static void vidtv_mux_discontinuity_random(struct vidtv_mux *m, u32 disc_prob, u16 pid)
+{
+ struct vidtv_mux_pid_ctx *ctx = vidtv_mux_get_pid_ctx(m, pid);
+
+ /* if the pkt was previously corrupted such that we cannot retrieve its pid context
+ * anymore, then bail
+ */
+ if (!ctx)
+ return;
+
+ if (prandom_u32_max(10000) < disc_prob)
+ vidtv_ts_inc_cc(&ctx->cc);
+}
+
+static u32 vidtv_mux_get_random_pkt_offset(struct vidtv_mux *m)
+{
+ u32 npkts = m->mux_buf_offset / TS_PACKET_LEN;
+ u32 pkt_offset = prandom_u32_max(npkts) * TS_PACKET_LEN;
+
+ return pkt_offset;
+}
+
+static u32 vidtv_mux_get_random_pkt_offset_for_pid(struct vidtv_mux *m, u16 pid, bool *found)
+{
+ u32 npkts_total = m->mux_buf_offset / TS_PACKET_LEN;
+ u8 *buf = kcalloc(npkts_total, sizeof(u32), GFP_KERNEL);
+ u32 npkt = 0;
+ u32 pkt_offset = 0;
+ u32 offset;
+ u16 pkt_pid;
+
+ for (offset = 0; offset < m->mux_buf_offset; offset += TS_PACKET_LEN) {
+ pkt_pid = vidtv_ts_get_pid(&m->mux_buf[offset]);
+ if (pkt_pid == pid) {
+ buf[npkt] = offset;
+ npkt++;
+ }
+ }
+
+ *found = (npkt != 0);
+ pkt_offset = buf[prandom_u32_max(npkt)];
+ kfree(buf);
+ return pkt_offset;
+}
+
+static void vidtv_mux_handle_debugfs_input(struct vidtv_mux *m, u32 *nbytes)
+{
+ struct vidtv_mux_pid_ctx *ctx;
+ u32 pkt_offset;
+ u16 pid;
+ int bkt;
+ bool found;
+ u32 offset;
+
+#ifndef CONFIG_DVB_VIDTV_DEBUGFS
+ return;
+#endif //CONFIG_DVB_VIDTV_DEBUGFS
+
+ if (m->mux_buf_offset == 0)
+ return;
+
+ while (m->debugfs.discontinuity > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset(m);
+ pid = vidtv_ts_get_pid(&m->mux_buf[pkt_offset]);
+ vidtv_mux_discontinuity_random(m, 10000, pid);
+ m->debugfs.discontinuity--;
+ }
+
+ while (m->debugfs.drop > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset(m);
+ vidtv_mux_drop_random(m, 10000, pkt_offset, nbytes);
+ m->debugfs.drop--;
+ }
+
+ while (m->debugfs.shl > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset(m);
+ vidtv_mux_shl_random(m, 10000, pkt_offset);
+ m->debugfs.shl--;
+ }
+
+ while (m->debugfs.shr > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset(m);
+ vidtv_mux_shr_random(m, 10000, pkt_offset);
+ m->debugfs.shr--;
+ }
+
+ for (offset = 0; offset < m->mux_buf_offset; offset += TS_PACKET_LEN) {
+ pid = vidtv_ts_get_pid(&m->mux_buf[offset]);
+ vidtv_mux_discontinuity_random(m, m->debugfs.discontinuity_probability, pid);
+ vidtv_mux_add_random_noise(m, m->debugfs.noise, offset);
+ vidtv_mux_drop_random(m, m->debugfs.drop_probability, offset, nbytes);
+ vidtv_mux_shl_random(m, m->debugfs.shl_probability, offset);
+ vidtv_mux_shr_random(m, m->debugfs.shr_probability, offset);
+ }
+
+ hash_for_each(m->pid_ctx, bkt, ctx, h) {
+ while (ctx->debugfs.discontinuity > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
+ vidtv_mux_discontinuity_random(m, 10000, ctx->pid);
+ ctx->debugfs.discontinuity--;
+ }
+
+ while (ctx->debugfs.drop > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
+ if (found)
+ vidtv_mux_drop_random(m, 10000, pkt_offset, nbytes);
+ ctx->debugfs.drop--;
+ }
+
+ while (ctx->debugfs.shl > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
+ if (found)
+ vidtv_mux_shl_random(m, 10000, pkt_offset);
+ ctx->debugfs.shl--;
+ }
+
+ while (ctx->debugfs.shr > 0) {
+ pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
+ if (found)
+ vidtv_mux_shr_random(m, 10000, pkt_offset);
+ ctx->debugfs.shr--;
+ }
+
+ for (offset = 0; offset < m->mux_buf_offset; offset += TS_PACKET_LEN) {
+ pid = vidtv_ts_get_pid(&m->mux_buf[offset]);
+ if (ctx->pid == pid) {
+ vidtv_mux_discontinuity_random(m,
+ m->debugfs.discontinuity_probability,
+ pid);
+ vidtv_mux_add_random_noise(m, ctx->debugfs.noise, offset);
+ vidtv_mux_drop_random(m, ctx->debugfs.drop_probability,
+ offset, nbytes);
+ vidtv_mux_shl_random(m, ctx->debugfs.shl_probability, offset);
+ vidtv_mux_shr_random(m, ctx->debugfs.shr_probability, offset);
+ }
+ }
+ }
+}
+
#define ERR_RATE 10000000
static void vidtv_mux_tick(struct work_struct *work)
{
@@ -410,6 +611,7 @@ static void vidtv_mux_tick(struct work_struct *work)
nbytes += vidtv_mux_poll_encoders(m);
nbytes += vidtv_mux_pad_with_nulls(m, 256);
+ vidtv_mux_handle_debugfs_input(m, &nbytes);
npkts = nbytes / TS_PACKET_LEN;
/* if the buffer is not aligned there is a bug somewhere */
@@ -474,6 +676,71 @@ void vidtv_mux_stop_thread(struct vidtv_mux *m)
}
}
+static void vidtv_mux_debugfs_init(struct vidtv_mux *m, struct dentry *parent)
+{
+ struct dentry *frontend_dir;
+ struct dentry *pid_dir;
+ struct vidtv_mux_pid_ctx *ctx;
+ int bkt;
+ char name[16];
+ struct dtv_frontend_properties *c;
+
+#ifndef CONFIG_DVB_VIDTV_DEBUGFS
+ return;
+#endif //CONFIG_DVB_VIDTV_DEBUGFS
+
+ c = &m->fe->dtv_property_cache;
+ //Change this if vidtv ever supports simulating more than one frontend
+ frontend_dir = debugfs_create_dir("frontend0", parent);
+ if (IS_ERR(frontend_dir))
+ return;
+
+ debugfs_create_u64("pre_bit_count", 0444, frontend_dir, &c->pre_bit_count.stat[0].uvalue);
+ debugfs_create_u64("post_bit_count", 0444, frontend_dir, &c->post_bit_count.stat[0].uvalue);
+ debugfs_create_u64("block_count", 0444, frontend_dir, &c->block_count.stat[0].uvalue);
+
+ /* these work at random for any PID in this mux */
+ debugfs_create_u32("noise", 0644, frontend_dir, &m->debugfs.noise);
+ debugfs_create_u32("drop_probability", 0644, frontend_dir, &m->debugfs.drop_probability);
+ debugfs_create_u32("shl_probability", 0644, frontend_dir, &m->debugfs.shl_probability);
+ debugfs_create_u32("shr_probability", 0644, frontend_dir, &m->debugfs.shr_probability);
+ debugfs_create_u32("discontinuity_probability", 0644, frontend_dir,
+ &m->debugfs.discontinuity_probability);
+ debugfs_create_u32("drop", 0644, frontend_dir, &m->debugfs.drop);
+ debugfs_create_u32("shl", 0644, frontend_dir, &m->debugfs.shl);
+ debugfs_create_u32("shr", 0644, frontend_dir, &m->debugfs.shr);
+ debugfs_create_u32("discontinuity", 0644, frontend_dir, &m->debugfs.discontinuity);
+
+ hash_for_each(m->pid_ctx, bkt, ctx, h) {
+ memset(name, 0, ARRAY_SIZE(name));
+ snprintf(name, ARRAY_SIZE(name), "PID_%d", ctx->pid);
+
+ pid_dir = debugfs_create_dir(name, frontend_dir);
+ if (IS_ERR(pid_dir))
+ return;
+
+ /* these will affect the chosen PID only */
+ debugfs_create_u32("noise", 0644, pid_dir, &ctx->debugfs.noise);
+ debugfs_create_u32("drop_probability", 0644, pid_dir,
+ &ctx->debugfs.drop_probability);
+ debugfs_create_u32("shl_probability", 0644, pid_dir,
+ &ctx->debugfs.shl_probability);
+ debugfs_create_u32("shr_probability", 0644, pid_dir,
+ &ctx->debugfs.shr_probability);
+ debugfs_create_u32("discontinuity_probability", 0644, pid_dir,
+ &ctx->debugfs.discontinuity_probability);
+ debugfs_create_u32("drop", 0644, pid_dir, &ctx->debugfs.drop);
+ debugfs_create_u32("shl", 0644, pid_dir, &ctx->debugfs.shl);
+ debugfs_create_u32("shr", 0644, pid_dir, &ctx->debugfs.shr);
+ debugfs_create_u32("discontinuity", 0644, pid_dir,
+ &ctx->debugfs.discontinuity);
+
+ ctx->debugfs.dir_dentry = pid_dir;
+ }
+
+ m->debugfs.dir_dentry = frontend_dir;
+}
+
struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
struct device *dev,
struct vidtv_mux_init_args *args)
@@ -521,6 +788,8 @@ struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
if (vidtv_mux_pid_ctx_init(m) < 0)
goto free_channel_si;
+ vidtv_mux_debugfs_init(m, args->debugfs_root);
+
return m;
free_channel_si:
@@ -542,5 +811,8 @@ void vidtv_mux_destroy(struct vidtv_mux *m)
vidtv_channels_destroy(m);
kfree(m->network_name);
vfree(m->mux_buf);
+#ifdef CONFIG_DVB_VIDTV_DEBUGFS
+ debugfs_remove_recursive(m->debugfs.dir_dentry);
+#endif //CONFIG_DVB_VIDTV_DEBUGFS
kfree(m);
}
diff --git a/drivers/media/test-drivers/vidtv/vidtv_mux.h b/drivers/media/test-drivers/vidtv/vidtv_mux.h
index ad82eb72b841..b6ca9f330afd 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_mux.h
+++ b/drivers/media/test-drivers/vidtv/vidtv_mux.h
@@ -22,6 +22,7 @@
#include <media/dvb_frontend.h>
#include "vidtv_psi.h"
+#include "vidtv_debugfs.h"
/**
* struct vidtv_mux_timing - Timing related information
@@ -77,11 +78,13 @@ struct vidtv_mux_si {
* @cc: The continuity counter for this PID. It is incremented on every TS
* pack and it will wrap around at 0xf0. If the decoder notices a sudden jump in
* this counter this will trigger a discontinuity state.
+ * @debugfs: debugfs interface for this mpeg pid
* @h: This is embedded in a hash table, mapping pid -> vidtv_mux_pid_ctx
*/
struct vidtv_mux_pid_ctx {
u16 pid;
u8 cc; /* continuity counter */
+ struct vidtv_debugfs debugfs;
struct hlist_node h;
};
@@ -108,6 +111,7 @@ struct vidtv_mux_pid_ctx {
* @transport_stream_id: The transport stream ID
* @network_id: The network ID
* @network_name: The network name
+ * @debugfs: The debugfs interface for the whole mux, if any.
* @priv: Private data.
*/
struct vidtv_mux {
@@ -139,6 +143,7 @@ struct vidtv_mux {
u16 transport_stream_id;
u16 network_id;
char *network_name;
+ struct vidtv_debugfs debugfs;
void *priv;
};
@@ -155,6 +160,7 @@ struct vidtv_mux {
* @channels: an optional list of channels to use
* @network_id: The network ID
* @network_name: The network name
+ * @debugfs_root: the debugfs root directory, if any
* @priv: Private data.
*/
struct vidtv_mux_init_args {
@@ -168,6 +174,7 @@ struct vidtv_mux_init_args {
struct vidtv_channel *channels;
u16 network_id;
char *network_name;
+ struct dentry *debugfs_root;
void *priv;
};
diff --git a/drivers/media/test-drivers/vidtv/vidtv_ts.c b/drivers/media/test-drivers/vidtv/vidtv_ts.c
index ca4bb9c40b78..dca6fa8afa57 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_ts.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_ts.c
@@ -134,3 +134,11 @@ u32 vidtv_ts_pcr_write_into(struct pcr_write_args args)
return nbytes;
}
+
+u16 vidtv_ts_get_pid(u8 *pkt)
+{
+ struct vidtv_mpeg_ts *ts_pkt = (struct vidtv_mpeg_ts *)pkt;
+ u16 bitfield = be16_to_cpu(ts_pkt->bitfield);
+ u16 ret = bitfield & GENMASK(12, 0);
+ return ret;
+}
diff --git a/drivers/media/test-drivers/vidtv/vidtv_ts.h b/drivers/media/test-drivers/vidtv/vidtv_ts.h
index 09b4ffd02829..f19824021966 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_ts.h
+++ b/drivers/media/test-drivers/vidtv/vidtv_ts.h
@@ -103,4 +103,12 @@ u32 vidtv_ts_null_write_into(struct null_packet_write_args args);
*/
u32 vidtv_ts_pcr_write_into(struct pcr_write_args args);
+/**
+ * vidtv_ts_get_pid - Extract the MPEG PID value out of a mpeg ts packet
+ * @pkt: pointer to packet
+ *
+ * Return: The mpeg ts pid in cpu endianness
+ */
+u16 vidtv_ts_get_pid(u8 *pkt);
+
#endif //VIDTV_TS_H
--
2.29.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 3/3] media: vidtv: add initial debugfs interface
2020-12-24 15:04 [PATCH 3/3] media: vidtv: add initial debugfs interface Daniel W. S. Almeida
@ 2021-01-27 11:06 ` Mauro Carvalho Chehab
2021-01-27 12:26 ` Daniel Almeida
0 siblings, 1 reply; 3+ messages in thread
From: Mauro Carvalho Chehab @ 2021-01-27 11:06 UTC (permalink / raw)
To: Daniel W. S. Almeida; +Cc: linux-media, linux-kernel-mentees, linux-kernel
Em Thu, 24 Dec 2020 12:04:02 -0300
"Daniel W. S. Almeida" <dwlsalmeida@gmail.com> escreveu:
> From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
>
> Add a debugfs interface for testing purposes that can be enabled
> by selecting **DVB_VIDTV_DEBUGFS**. This makes it possible to:
>
> dynamically inject errors at runtime by interacting with the files
> at /sys/kernel/debug/vidtv/*
>
> read some dvbv5 statistics from userspace more easily.
>
> This is entirely optional and the driver will work without this option
> selected.
Patches 1 and 2 on this series seem OK. I'm applying them, after
testing.
Please see the notes below for this one.
>
> Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> ---
> .../driver-api/media/drivers/vidtv.rst | 80 +++---
> drivers/media/test-drivers/vidtv/Kconfig | 13 +
> .../media/test-drivers/vidtv/vidtv_bridge.c | 13 +
> .../media/test-drivers/vidtv/vidtv_bridge.h | 2 +
> .../media/test-drivers/vidtv/vidtv_debugfs.h | 42 +++
> drivers/media/test-drivers/vidtv/vidtv_mux.c | 272 ++++++++++++++++++
> drivers/media/test-drivers/vidtv/vidtv_mux.h | 7 +
> drivers/media/test-drivers/vidtv/vidtv_ts.c | 8 +
> drivers/media/test-drivers/vidtv/vidtv_ts.h | 8 +
> 9 files changed, 412 insertions(+), 33 deletions(-)
> create mode 100644 drivers/media/test-drivers/vidtv/vidtv_debugfs.h
>
> diff --git a/Documentation/driver-api/media/drivers/vidtv.rst b/Documentation/driver-api/media/drivers/vidtv.rst
> index 673bdff919ea..e7c450289774 100644
> --- a/Documentation/driver-api/media/drivers/vidtv.rst
> +++ b/Documentation/driver-api/media/drivers/vidtv.rst
> @@ -227,6 +227,9 @@ vidtv_mux.[ch]
> #. Delivering the resulting TS packets to the bridge
> driver so it can pass them to the demux.
>
> +vidtv_debugfs.h
> + Exposes data structures used in vidtv's debugfs interface.
> +
> Testing vidtv with v4l-utils
> ----------------------------
>
> @@ -431,27 +434,53 @@ For more information on dvb-zap check its online documentation here:
> See also: `zap <https://www.linuxtv.org/wiki/index.php/Zap>`_.
>
>
> -What can still be improved in vidtv
> ------------------------------------
> +Vidtv *debugfs* integration
> +___________________________
> +
> +Vidtv now comes with a *debugfs* interface that can be enabled by selecting
> +**DVB_VIDTV_DEBUGFS**. Using it, one can
"now comes" -> "can be compiled"
> +
> +#. dynamically inject errors at runtime by interacting with the files at /sys/kernel/debug/vidtv/*
> +
> +#. read some dvbv5 statistics from userspace more easily
> +
> +.. note::
> + This is entirely optional and the driver will work without this option selected.
Please keep lines <= 80 columns, except when there's a strong reason to
use longer lines. The same applies to other parts of this patch.
> +
> +At boot, vidtv will set up a directory per simulated frontend. Here is a list of
> +created files and their associated functionality once they are written to:
> +
> +noise
> + The probability of adding random noise in the packets (0 - 10000).
> +drop
> + Drop n packets at random
> +shl
> + Shift left n bytes at random
> +shr
> + Shift right n bytes at random
> +discontinuity
> + Create n discontinuities at random. This means artificially increasing
> + the continuity counters such that a discontinuity error is generated.
> +
> +Another option is to provide a probability of such events ocurring. Drop, shl,
> +shr, and discontinuity have versions that take in a probability in the [0,
> +10000] range.
>
> -Add *debugfs* integration
> -~~~~~~~~~~~~~~~~~~~~~~~~~
> +Writing to the files at the frontend directory will target all packets in the
> +mux buffer. Alternatively, vidtv will also create a directory per PID. Writing
> +to these files will, in turn, only affect that particular PID.
>
> -Although frontend drivers provide DVBv5 statistics via the .read_status
> -call, a nice addition would be to make additional statistics available to
> -userspace via debugfs, which is a simple-to-use, RAM-based filesystem
> -specifically designed for debug purposes.
>
> -The logic for this would be implemented on a separate file so as not to
> -pollute the frontend driver. These statistics are driver-specific and can
> -be useful during tests.
> +What can still be improved in vidtv
> +-----------------------------------
> +
> +Improve debugfs support
> +~~~~~~~~~~~~~~~~~~~~~~~
>
> -The Siano driver is one example of a driver using
> -debugfs to convey driver-specific statistics to userspace and it can be
> -used as a reference.
> +Vidtv offers support for dynamically injecting errors and retrieving some dvbv5
> +stats via *debugfs*. This can be improved upon to add new ways of testing from
> +userspace.
>
> -This should be further enabled and disabled via a Kconfig
> -option for convenience.
>
> Add a way to test video
> ~~~~~~~~~~~~~~~~~~~~~~~
> @@ -468,23 +497,6 @@ which resides at::
> drivers/media/common/v4l2-tpg/
>
>
> -Add white noise simulation
> -~~~~~~~~~~~~~~~~~~~~~~~~~~
> -
> -The vidtv tuner already has code to identify whether the chosen frequency
> -is too far away from a table of valid frequencies. For now, this means that
> -the demodulator can eventually lose the lock on the signal, since the tuner will
> -report a bad signal quality.
> -
> -A nice addition is to simulate some noise when the signal quality is bad by:
> -
> -- Randomly dropping some TS packets. This will trigger a continuity error if the
> - continuity counter is updated but the packet is not passed on to the demux.
> -
> -- Updating the error statistics accordingly (e.g. BER, etc).
> -
> -- Simulating some noise in the encoded data.
> -
> Functions and structs used within vidtv
> ---------------------------------------
>
> @@ -511,3 +523,5 @@ Functions and structs used within vidtv
> .. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_common.c
>
> .. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_tuner.c
> +
> +.. kernel-doc:: drivers/media/test-drivers/vidtv/vidtv_debugfs.h
> diff --git a/drivers/media/test-drivers/vidtv/Kconfig b/drivers/media/test-drivers/vidtv/Kconfig
> index 22c4fd39461f..05513f1c67e1 100644
> --- a/drivers/media/test-drivers/vidtv/Kconfig
> +++ b/drivers/media/test-drivers/vidtv/Kconfig
> @@ -8,4 +8,17 @@ config DVB_VIDTV
> working on userspace applications.
>
>
> + When in doubt, say N.
> +
> +config DVB_VIDTV_DEBUGFS
> + bool "Enable debugfs for vidtv"
> + depends on DVB_VIDTV
> + depends on DEBUG_FS
> +
> + help
> + Choose Y to enable the vidtv debugfs interface. Currently allows for
> + dynamically introducing errors in the generated MPEG Transport Stream
> + for testing purposes.
> +
> +
> When in doubt, say N.
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
> index fc64d0c8492a..d5ebe680724f 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c
> +++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
> @@ -10,6 +10,7 @@
> * Copyright (C) 2020 Daniel W. S. Almeida
> */
>
> +#include <linux/debugfs.h>
> #include <linux/dev_printk.h>
> #include <linux/moduleparam.h>
> #include <linux/mutex.h>
> @@ -172,6 +173,7 @@ static int vidtv_start_streaming(struct vidtv_dvb *dvb)
> .transport_stream_id = VIDTV_DEFAULT_TS_ID,
> .network_id = VIDTV_DEFAULT_NETWORK_ID,
> .network_name = VIDTV_DEFAULT_NETWORK_NAME,
> + .debugfs_root = dvb->debugfs_root,
> .priv = dvb,
> };
> struct device *dev = &dvb->pdev->dev;
> @@ -485,6 +487,7 @@ static int vidtv_bridge_dvb_init(struct vidtv_dvb *dvb)
> static int vidtv_bridge_probe(struct platform_device *pdev)
> {
> struct vidtv_dvb *dvb;
> + struct dentry *debugfs_root;
> int ret;
>
> dvb = kzalloc(sizeof(*dvb), GFP_KERNEL);
> @@ -501,6 +504,12 @@ static int vidtv_bridge_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, dvb);
>
> +#ifdef CONFIG_DVB_VIDTV_DEBUGFS
> + debugfs_root = debugfs_create_dir("vidtv", NULL);
> + if (!IS_ERR(debugfs_root))
> + dvb->debugfs_root = debugfs_root;
> +#endif //CONFIG_DVB_VIDTV_DEBUGFS
> +
While C99 comments are now allowed, we still prefer to use C89 ones:
#endif /* CONFIG_DVB_VIDTV_DEBUGFS */
(also, please add a space after the comment tag, as it makes easier
for read the comment)
> dev_info(&pdev->dev, "Successfully initialized vidtv!\n");
> return ret;
>
> @@ -516,6 +525,10 @@ static int vidtv_bridge_remove(struct platform_device *pdev)
>
> dvb = platform_get_drvdata(pdev);
>
> +#ifdef CONFIG_DVB_VIDTV_DEBUGFS
> + debugfs_remove_recursive(dvb->debugfs_root);
> +#endif //CONFIG_DVB_VIDTV_DEBUGFS
> +
> mutex_destroy(&dvb->feed_lock);
>
> for (i = 0; i < NUM_FE; ++i) {
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.h b/drivers/media/test-drivers/vidtv/vidtv_bridge.h
> index 2528adaee27d..9ef37d8ad2cc 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_bridge.h
> +++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.h
> @@ -42,6 +42,7 @@
> * @feed_lock: Protects access to the start/stop stream logic/data.
> * @streaming: Whether we are streaming now.
> * @mux: The abstraction responsible for delivering MPEG TS packets to the bridge.
> + * @debugfs_root: A handle to vidtv's debugfs directory
> */
> struct vidtv_dvb {
> struct platform_device *pdev;
> @@ -60,6 +61,7 @@ struct vidtv_dvb {
> bool streaming;
>
> struct vidtv_mux *mux;
> + struct dentry *debugfs_root;
> };
>
> #endif // VIDTV_BRIDG_H
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_debugfs.h b/drivers/media/test-drivers/vidtv/vidtv_debugfs.h
> new file mode 100644
> index 000000000000..1743fe6d96cf
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_debugfs.h
> @@ -0,0 +1,42 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Vidtv serves as a reference DVB driver and helps validate the existing APIs
> + * in the media subsystem. It can also aid developers working on userspace
> + * applications.
> + *
> + * Copyright (C) 2020 Daniel W. S. Almeida
> + */
> +
> +#ifndef VIDTV_DEBUGFS_H
> +#define VIDTV_DEBUGFS_H
> +#include <linux/debugfs.h>
> +
> +/**
> + * struct vidtv_debugfs - Represents the vidtv debugfs interface
> + *
> + * @dir_dentry: A handle to the debugfs dentry
> + * @noise: Probability of adding noise to a byte in a packet [0, 10000]
> + * @drop: Drop n packets at random.
> + * @drop_probability: Probability to randomly drop a packet [0, 10000]
> + * @shl_probability: Probability to randomly shift left a byte in a packet [0, 10000]
> + * @shr_probability: Probability to randomly shift right a byte in a packet [0, 10000]
> + * @discontinuity_probability: Probability of artificially creating a
> + * discontinuity error [0, 10000]
> + * @shl: Shift n bytes left at random, i.e. byte[i] = byte[i] << 1;
> + * @shr: Shift n bytes right at random, i.e. byte[i] = byte[i] >>1;
> + * @discontinuity: Create n discontinuity errors
> + */
> +struct vidtv_debugfs {
> + struct dentry *dir_dentry;
> + u32 noise;
> + u32 drop_probability;
> + u32 shl_probability;
> + u32 shr_probability;
> + u32 discontinuity_probability;
> + u32 drop;
> + u32 shl;
> + u32 shr;
> + u32 discontinuity;
> +};
> +
> +#endif //VIDTV_DEBUGFS_H
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_mux.c b/drivers/media/test-drivers/vidtv/vidtv_mux.c
> index b51e6a3b8cbe..e6d69fe01908 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_mux.c
> +++ b/drivers/media/test-drivers/vidtv/vidtv_mux.c
> @@ -12,11 +12,14 @@
> * Copyright (C) 2020 Daniel W. S. Almeida
> */
>
> +#include "vidtv_debugfs.h"
> +#include <linux/debugfs.h>
> #include <linux/delay.h>
> #include <linux/dev_printk.h>
> #include <linux/jiffies.h>
> #include <linux/kernel.h>
> #include <linux/math64.h>
> +#include <linux/random.h>
> #include <linux/ratelimit.h>
> #include <linux/slab.h>
> #include <linux/types.h>
> @@ -385,6 +388,204 @@ static void vidtv_mux_clear(struct vidtv_mux *m)
> m->mux_buf_offset = 0;
> }
>
> +static void vidtv_mux_add_random_noise(struct vidtv_mux *m, u32 noise_prob, u32 pkt_start)
> +{
> + u8 noise;
> + u8 *pkt = m->mux_buf + pkt_start;
> + u32 i;
> +
> + for (i = 0; i < TS_PACKET_LEN; i++)
> + if (prandom_u32_max(10000) < noise_prob) {
> + noise = prandom_u32_max(0xff);
> + pkt[i] = pkt[i] + noise;
> + }
> +}
> +
> +static void vidtv_mux_drop_random(struct vidtv_mux *m, u32 drop_prob, u32 pkt_start, u32 *nbytes)
> +{
> + u8 *pkt = m->mux_buf + pkt_start;
> + u8 *last_pkt = m->mux_buf + m->mux_buf_offset - TS_PACKET_LEN;
> + u32 npkts = m->mux_buf_offset / 188;
> +
> + if (!npkts)
> + return;
> +
> + if (prandom_u32_max(10000) < drop_prob) {
> + if (npkts > 1 && pkt != last_pkt) {
> + //overwrite victim with last packet
> + memcpy(pkt, last_pkt, TS_PACKET_LEN);
> + //remove last packet from buffer
> + memset(last_pkt, 0, TS_PACKET_LEN);
> + } else {
> + //just erase it
> + memset(pkt, 0, TS_PACKET_LEN);
> + }
> +
> + //keep track of the loss of this packet
> + m->mux_buf_offset -= TS_PACKET_LEN;
> + *nbytes -= TS_PACKET_LEN;
> + }
> +}
> +
> +static void vidtv_mux_shl_random(struct vidtv_mux *m, u32 shl_prob, u32 pkt_start)
> +{
> + u8 *pkt = m->mux_buf + pkt_start;
> + /* select one of the 188 bytes at random */
> + u8 *byte = pkt + prandom_u32_max(TS_PACKET_LEN);
> +
> + if (prandom_u32_max(10000) < shl_prob)
> + *byte = *byte << 1;
> +}
> +
> +static void vidtv_mux_shr_random(struct vidtv_mux *m, u32 shr_prob, u32 pkt_start)
> +{
> + u8 *pkt = m->mux_buf + pkt_start;
> + /* select one of the 188 bytes at random */
> + u8 *byte = pkt + prandom_u32_max(TS_PACKET_LEN);
> +
> + if (prandom_u32_max(10000) < shr_prob)
> + *byte = *byte >> 1;
> +}
> +
> +static void vidtv_mux_discontinuity_random(struct vidtv_mux *m, u32 disc_prob, u16 pid)
> +{
> + struct vidtv_mux_pid_ctx *ctx = vidtv_mux_get_pid_ctx(m, pid);
> +
> + /* if the pkt was previously corrupted such that we cannot retrieve its pid context
> + * anymore, then bail
> + */
> + if (!ctx)
> + return;
> +
> + if (prandom_u32_max(10000) < disc_prob)
> + vidtv_ts_inc_cc(&ctx->cc);
> +}
> +
> +static u32 vidtv_mux_get_random_pkt_offset(struct vidtv_mux *m)
> +{
> + u32 npkts = m->mux_buf_offset / TS_PACKET_LEN;
> + u32 pkt_offset = prandom_u32_max(npkts) * TS_PACKET_LEN;
> +
> + return pkt_offset;
> +}
> +
> +static u32 vidtv_mux_get_random_pkt_offset_for_pid(struct vidtv_mux *m, u16 pid, bool *found)
> +{
> + u32 npkts_total = m->mux_buf_offset / TS_PACKET_LEN;
> + u8 *buf = kcalloc(npkts_total, sizeof(u32), GFP_KERNEL);
> + u32 npkt = 0;
> + u32 pkt_offset = 0;
> + u32 offset;
> + u16 pkt_pid;
> +
> + for (offset = 0; offset < m->mux_buf_offset; offset += TS_PACKET_LEN) {
> + pkt_pid = vidtv_ts_get_pid(&m->mux_buf[offset]);
> + if (pkt_pid == pid) {
> + buf[npkt] = offset;
> + npkt++;
> + }
> + }
> +
> + *found = (npkt != 0);
> + pkt_offset = buf[prandom_u32_max(npkt)];
> + kfree(buf);
> + return pkt_offset;
> +}
Please create a drivers/media/test-drivers/vidtv/vidtv_debugfs.c file
and place everything related to debugfs on it.
At the header file, you would do:
#if CONFIG_DVB_VIDTV_DEBUGFS
u32 vidtv_mux_get_random_pkt_offset_for_pid(struct vidtv_mux *m,
u16 pid, bool *found);
#else
static inline u32 vidtv_mux_get_random_pkt_offset_for_pid(struct vidtv_mux *m,
u16 pid, bool *found)
{
return 0;
}
#endif
for all functions. This way, the C files will be cleaner, as there
won't be any "#if" inside them, and the header files will declare
function stubs that will do nothing, which causes the compiler to
simply discard the entire function as a hole.
> +
> +static void vidtv_mux_handle_debugfs_input(struct vidtv_mux *m, u32 *nbytes)
> +{
> + struct vidtv_mux_pid_ctx *ctx;
> + u32 pkt_offset;
> + u16 pid;
> + int bkt;
> + bool found;
> + u32 offset;
> +
> +#ifndef CONFIG_DVB_VIDTV_DEBUGFS
> + return;
> +#endif //CONFIG_DVB_VIDTV_DEBUGFS
Never do that! if compiled without CONFIG_DVB_VIDTV_DEBUGFS, there
will be dead code at the function.
> +
> + if (m->mux_buf_offset == 0)
> + return;
> +
> + while (m->debugfs.discontinuity > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset(m);
> + pid = vidtv_ts_get_pid(&m->mux_buf[pkt_offset]);
> + vidtv_mux_discontinuity_random(m, 10000, pid);
> + m->debugfs.discontinuity--;
> + }
> +
> + while (m->debugfs.drop > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset(m);
> + vidtv_mux_drop_random(m, 10000, pkt_offset, nbytes);
> + m->debugfs.drop--;
> + }
> +
> + while (m->debugfs.shl > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset(m);
> + vidtv_mux_shl_random(m, 10000, pkt_offset);
> + m->debugfs.shl--;
> + }
> +
> + while (m->debugfs.shr > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset(m);
> + vidtv_mux_shr_random(m, 10000, pkt_offset);
> + m->debugfs.shr--;
> + }
> +
> + for (offset = 0; offset < m->mux_buf_offset; offset += TS_PACKET_LEN) {
> + pid = vidtv_ts_get_pid(&m->mux_buf[offset]);
> + vidtv_mux_discontinuity_random(m, m->debugfs.discontinuity_probability, pid);
> + vidtv_mux_add_random_noise(m, m->debugfs.noise, offset);
> + vidtv_mux_drop_random(m, m->debugfs.drop_probability, offset, nbytes);
> + vidtv_mux_shl_random(m, m->debugfs.shl_probability, offset);
> + vidtv_mux_shr_random(m, m->debugfs.shr_probability, offset);
> + }
> +
> + hash_for_each(m->pid_ctx, bkt, ctx, h) {
> + while (ctx->debugfs.discontinuity > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
> + vidtv_mux_discontinuity_random(m, 10000, ctx->pid);
> + ctx->debugfs.discontinuity--;
> + }
> +
> + while (ctx->debugfs.drop > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
> + if (found)
> + vidtv_mux_drop_random(m, 10000, pkt_offset, nbytes);
> + ctx->debugfs.drop--;
> + }
> +
> + while (ctx->debugfs.shl > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
> + if (found)
> + vidtv_mux_shl_random(m, 10000, pkt_offset);
> + ctx->debugfs.shl--;
> + }
> +
> + while (ctx->debugfs.shr > 0) {
> + pkt_offset = vidtv_mux_get_random_pkt_offset_for_pid(m, ctx->pid, &found);
> + if (found)
> + vidtv_mux_shr_random(m, 10000, pkt_offset);
> + ctx->debugfs.shr--;
> + }
> +
> + for (offset = 0; offset < m->mux_buf_offset; offset += TS_PACKET_LEN) {
> + pid = vidtv_ts_get_pid(&m->mux_buf[offset]);
> + if (ctx->pid == pid) {
> + vidtv_mux_discontinuity_random(m,
> + m->debugfs.discontinuity_probability,
> + pid);
> + vidtv_mux_add_random_noise(m, ctx->debugfs.noise, offset);
> + vidtv_mux_drop_random(m, ctx->debugfs.drop_probability,
> + offset, nbytes);
> + vidtv_mux_shl_random(m, ctx->debugfs.shl_probability, offset);
> + vidtv_mux_shr_random(m, ctx->debugfs.shr_probability, offset);
> + }
> + }
> + }
> +}
> +
> #define ERR_RATE 10000000
> static void vidtv_mux_tick(struct work_struct *work)
> {
> @@ -410,6 +611,7 @@ static void vidtv_mux_tick(struct work_struct *work)
> nbytes += vidtv_mux_poll_encoders(m);
> nbytes += vidtv_mux_pad_with_nulls(m, 256);
>
> + vidtv_mux_handle_debugfs_input(m, &nbytes);
> npkts = nbytes / TS_PACKET_LEN;
>
> /* if the buffer is not aligned there is a bug somewhere */
> @@ -474,6 +676,71 @@ void vidtv_mux_stop_thread(struct vidtv_mux *m)
> }
> }
>
> +static void vidtv_mux_debugfs_init(struct vidtv_mux *m, struct dentry *parent)
> +{
> + struct dentry *frontend_dir;
> + struct dentry *pid_dir;
> + struct vidtv_mux_pid_ctx *ctx;
> + int bkt;
> + char name[16];
> + struct dtv_frontend_properties *c;
> +
> +#ifndef CONFIG_DVB_VIDTV_DEBUGFS
> + return;
> +#endif //CONFIG_DVB_VIDTV_DEBUGFS
Same above notes apply here: place it on a separate C file and don't
keep dead code, using the inline void do-nothing functions at the header,
if compiled without CONFIG_DVB_VIDTV_DEBUGFS.
> +
> + c = &m->fe->dtv_property_cache;
> + //Change this if vidtv ever supports simulating more than one frontend
> + frontend_dir = debugfs_create_dir("frontend0", parent);
> + if (IS_ERR(frontend_dir))
> + return;
> +
> + debugfs_create_u64("pre_bit_count", 0444, frontend_dir, &c->pre_bit_count.stat[0].uvalue);
> + debugfs_create_u64("post_bit_count", 0444, frontend_dir, &c->post_bit_count.stat[0].uvalue);
> + debugfs_create_u64("block_count", 0444, frontend_dir, &c->block_count.stat[0].uvalue);
> +
> + /* these work at random for any PID in this mux */
> + debugfs_create_u32("noise", 0644, frontend_dir, &m->debugfs.noise);
> + debugfs_create_u32("drop_probability", 0644, frontend_dir, &m->debugfs.drop_probability);
> + debugfs_create_u32("shl_probability", 0644, frontend_dir, &m->debugfs.shl_probability);
> + debugfs_create_u32("shr_probability", 0644, frontend_dir, &m->debugfs.shr_probability);
> + debugfs_create_u32("discontinuity_probability", 0644, frontend_dir,
> + &m->debugfs.discontinuity_probability);
> + debugfs_create_u32("drop", 0644, frontend_dir, &m->debugfs.drop);
> + debugfs_create_u32("shl", 0644, frontend_dir, &m->debugfs.shl);
> + debugfs_create_u32("shr", 0644, frontend_dir, &m->debugfs.shr);
> + debugfs_create_u32("discontinuity", 0644, frontend_dir, &m->debugfs.discontinuity);
> +
> + hash_for_each(m->pid_ctx, bkt, ctx, h) {
> + memset(name, 0, ARRAY_SIZE(name));
> + snprintf(name, ARRAY_SIZE(name), "PID_%d", ctx->pid);
> +
> + pid_dir = debugfs_create_dir(name, frontend_dir);
> + if (IS_ERR(pid_dir))
> + return;
> +
> + /* these will affect the chosen PID only */
> + debugfs_create_u32("noise", 0644, pid_dir, &ctx->debugfs.noise);
> + debugfs_create_u32("drop_probability", 0644, pid_dir,
> + &ctx->debugfs.drop_probability);
> + debugfs_create_u32("shl_probability", 0644, pid_dir,
> + &ctx->debugfs.shl_probability);
> + debugfs_create_u32("shr_probability", 0644, pid_dir,
> + &ctx->debugfs.shr_probability);
> + debugfs_create_u32("discontinuity_probability", 0644, pid_dir,
> + &ctx->debugfs.discontinuity_probability);
> + debugfs_create_u32("drop", 0644, pid_dir, &ctx->debugfs.drop);
> + debugfs_create_u32("shl", 0644, pid_dir, &ctx->debugfs.shl);
> + debugfs_create_u32("shr", 0644, pid_dir, &ctx->debugfs.shr);
> + debugfs_create_u32("discontinuity", 0644, pid_dir,
> + &ctx->debugfs.discontinuity);
> +
> + ctx->debugfs.dir_dentry = pid_dir;
> + }
> +
> + m->debugfs.dir_dentry = frontend_dir;
> +}
> +
> struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
> struct device *dev,
> struct vidtv_mux_init_args *args)
> @@ -521,6 +788,8 @@ struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
> if (vidtv_mux_pid_ctx_init(m) < 0)
> goto free_channel_si;
>
> + vidtv_mux_debugfs_init(m, args->debugfs_root);
> +
> return m;
>
> free_channel_si:
> @@ -542,5 +811,8 @@ void vidtv_mux_destroy(struct vidtv_mux *m)
> vidtv_channels_destroy(m);
> kfree(m->network_name);
> vfree(m->mux_buf);
> +#ifdef CONFIG_DVB_VIDTV_DEBUGFS
> + debugfs_remove_recursive(m->debugfs.dir_dentry);
> +#endif //CONFIG_DVB_VIDTV_DEBUGFS
Instead, please do something like this at the .h file:
#ifdef CONFIG_DVB_VIDTV_DEBUGFS
...
vidtv_mux_debugfs_remove(...)
{
debugfs_remove_recursive(m->debugfs.dir_dentry);
}
...
#else
...
static inline vidtv_mux_debugfs_remove(...) {}
...
#endif
and just call it unconditionally here.
> kfree(m);
> }
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_mux.h b/drivers/media/test-drivers/vidtv/vidtv_mux.h
> index ad82eb72b841..b6ca9f330afd 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_mux.h
> +++ b/drivers/media/test-drivers/vidtv/vidtv_mux.h
> @@ -22,6 +22,7 @@
> #include <media/dvb_frontend.h>
>
> #include "vidtv_psi.h"
> +#include "vidtv_debugfs.h"
>
> /**
> * struct vidtv_mux_timing - Timing related information
> @@ -77,11 +78,13 @@ struct vidtv_mux_si {
> * @cc: The continuity counter for this PID. It is incremented on every TS
> * pack and it will wrap around at 0xf0. If the decoder notices a sudden jump in
> * this counter this will trigger a discontinuity state.
> + * @debugfs: debugfs interface for this mpeg pid
> * @h: This is embedded in a hash table, mapping pid -> vidtv_mux_pid_ctx
> */
> struct vidtv_mux_pid_ctx {
> u16 pid;
> u8 cc; /* continuity counter */
> + struct vidtv_debugfs debugfs;
> struct hlist_node h;
> };
>
> @@ -108,6 +111,7 @@ struct vidtv_mux_pid_ctx {
> * @transport_stream_id: The transport stream ID
> * @network_id: The network ID
> * @network_name: The network name
> + * @debugfs: The debugfs interface for the whole mux, if any.
> * @priv: Private data.
> */
> struct vidtv_mux {
> @@ -139,6 +143,7 @@ struct vidtv_mux {
> u16 transport_stream_id;
> u16 network_id;
> char *network_name;
> + struct vidtv_debugfs debugfs;
> void *priv;
> };
>
> @@ -155,6 +160,7 @@ struct vidtv_mux {
> * @channels: an optional list of channels to use
> * @network_id: The network ID
> * @network_name: The network name
> + * @debugfs_root: the debugfs root directory, if any
> * @priv: Private data.
> */
> struct vidtv_mux_init_args {
> @@ -168,6 +174,7 @@ struct vidtv_mux_init_args {
> struct vidtv_channel *channels;
> u16 network_id;
> char *network_name;
> + struct dentry *debugfs_root;
> void *priv;
> };
>
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_ts.c b/drivers/media/test-drivers/vidtv/vidtv_ts.c
> index ca4bb9c40b78..dca6fa8afa57 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_ts.c
> +++ b/drivers/media/test-drivers/vidtv/vidtv_ts.c
> @@ -134,3 +134,11 @@ u32 vidtv_ts_pcr_write_into(struct pcr_write_args args)
>
> return nbytes;
> }
> +
> +u16 vidtv_ts_get_pid(u8 *pkt)
> +{
> + struct vidtv_mpeg_ts *ts_pkt = (struct vidtv_mpeg_ts *)pkt;
> + u16 bitfield = be16_to_cpu(ts_pkt->bitfield);
> + u16 ret = bitfield & GENMASK(12, 0);
> + return ret;
> +}
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_ts.h b/drivers/media/test-drivers/vidtv/vidtv_ts.h
> index 09b4ffd02829..f19824021966 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_ts.h
> +++ b/drivers/media/test-drivers/vidtv/vidtv_ts.h
> @@ -103,4 +103,12 @@ u32 vidtv_ts_null_write_into(struct null_packet_write_args args);
> */
> u32 vidtv_ts_pcr_write_into(struct pcr_write_args args);
>
> +/**
> + * vidtv_ts_get_pid - Extract the MPEG PID value out of a mpeg ts packet
> + * @pkt: pointer to packet
> + *
> + * Return: The mpeg ts pid in cpu endianness
> + */
> +u16 vidtv_ts_get_pid(u8 *pkt);
> +
> #endif //VIDTV_TS_H
Thanks,
Mauro
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 3/3] media: vidtv: add initial debugfs interface
2021-01-27 11:06 ` Mauro Carvalho Chehab
@ 2021-01-27 12:26 ` Daniel Almeida
0 siblings, 0 replies; 3+ messages in thread
From: Daniel Almeida @ 2021-01-27 12:26 UTC (permalink / raw)
To: Mauro Carvalho Chehab; +Cc: linux-media, linux-kernel-mentees, linux-kernel
Hi Mauro! Thanks for the review.
Just one more thing though: what did you think about the way I chose to
inject the errors? (e.g. drop packet, shift bytes, create
discontinuity...etc etc)
I was just trying out a few ideas in this patch so if you also have any
input on this please let me know.
As of now writing to any of these files will cause a myriad of errors on
dvbinspector.
>> +
>> +#. dynamically inject errors at runtime by interacting with the files at /sys/kernel/debug/vidtv/*
>> +
>> +#. read some dvbv5 statistics from userspace more easily
>> +
>> +.. note::
>> + This is entirely optional and the driver will work without this option selected.
> Please keep lines <= 80 columns, except when there's a strong reason to
> use longer lines. The same applies to other parts of this patch.
>
I was under the assumption that this had been bumped to 100 recently.
-- thanks
-- Daniel
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-01-27 12:32 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-24 15:04 [PATCH 3/3] media: vidtv: add initial debugfs interface Daniel W. S. Almeida
2021-01-27 11:06 ` Mauro Carvalho Chehab
2021-01-27 12:26 ` Daniel Almeida
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