[PATCH v8 2/4] drm: Add API for capturing frame CRCs

Tomeu Vizoso
2016-09-09T09:57:26Z

Adds files and directories to debugfs for controlling and reading frame
CRCs, per CRTC:

dri/0/crtc-0/crc
dri/0/crtc-0/crc/control
dri/0/crtc-0/crc/data

Drivers can implement the set_crc_source callback() in drm_crtc_funcs to
start and stop generating frame CRCs and can add entries to the output
by calling drm_crtc_add_crc_entry.

v2:
- Lots of good fixes suggested by Thierry.
- Added documentation.
- Changed the debugfs layout.
- Moved to allocate the entries circular queue once when frame
generation gets enabled for the first time.
v3:
- Use the control file just to select the source, and start and stop
capture when the data file is opened and closed, respectively.
- Make variable the number of CRC values per entry, per source.
- Allocate entries queue each time we start capturing as now there
isn't a fixed number of CRC values per entry.
- Store the frame counter in the data file as a 8-digit hex number.
- For sources that cannot provide useful frame numbers, place
XXXXXXXX in the frame field.

v4:
- Build only if CONFIG_DEBUG_FS is enabled.
- Use memdup_user_nul.
- Consolidate calculation of the size of an entry in a helper.
- Add 0x prefix to hex numbers in the data file.
- Remove unnecessary snprintf and strlen usage in read callback.

v5:
- Made the crcs array in drm_crtc_crc_entry fixed-size
- Lots of other smaller improvements suggested by Emil Velikov

v7:
- Move definition of drm_debugfs_crtc_crc_add to drm_internal.h

v8:
- Call debugfs_remove_recursive when we fail to create the minor
device

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
---

Documentation/gpu/drm-uapi.rst | 6 +
drivers/gpu/drm/Makefile | 3 +-
drivers/gpu/drm/drm_crtc.c | 29 +++-
drivers/gpu/drm/drm_debugfs.c | 34 +++-
drivers/gpu/drm/drm_debugfs_crc.c | 351 ++++++++++++++++++++++++++++++++++++++
drivers/gpu/drm/drm_drv.c | 19 +++
drivers/gpu/drm/drm_internal.h | 16 ++
include/drm/drm_crtc.h | 41 +++++
include/drm/drm_debugfs_crc.h | 73 ++++++++
9 files changed, 569 insertions(+), 3 deletions(-)
create mode 100644 drivers/gpu/drm/drm_debugfs_crc.c
create mode 100644 include/drm/drm_debugfs_crc.h

diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst
index 1ba301cebe16..de3ac9f90f8f 100644
--- a/Documentation/gpu/drm-uapi.rst
+++ b/Documentation/gpu/drm-uapi.rst
@@ -216,3 +216,9 @@ interfaces. Especially since all hardware-acceleration interfaces to
userspace are driver specific for efficiency and other reasons these
interfaces can be rather substantial. Hence every driver has its own
chapter.
+
+Testing and validation
+======================
+
+.. kernel-doc:: drivers/gpu/drm/drm_debugfs_crc.c
+ :doc: CRC ABI
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 439d89b25ae0..60db76bbb02a 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -9,7 +9,7 @@ drm-y := drm_auth.o drm_bufs.o drm_cache.o \
drm_scatter.o drm_pci.o \
drm_platform.o drm_sysfs.o drm_hashtab.o drm_mm.o \
drm_crtc.o drm_fourcc.o drm_modes.o drm_edid.o \
- drm_info.o drm_debugfs.o drm_encoder_slave.o \
+ drm_info.o drm_encoder_slave.o \
drm_trace_points.o drm_global.o drm_prime.o \
drm_rect.o drm_vma_manager.o drm_flip_work.o \
drm_modeset_lock.o drm_atomic.o drm_bridge.o \
@@ -22,6 +22,7 @@ drm-$(CONFIG_PCI) += ati_pcigart.o
drm-$(CONFIG_DRM_PANEL) += drm_panel.o
drm-$(CONFIG_OF) += drm_of.o
drm-$(CONFIG_AGP) += drm_agpsupport.o
+drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o

drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index d84a0ead8100..9363dd597d3c 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -40,7 +40,7 @@
#include <drm/drm_modeset_lock.h>
#include <drm/drm_atomic.h>
#include <drm/drm_auth.h>
-#include <drm/drm_framebuffer.h>
+#include <drm/drm_debugfs_crc.h>

#include "drm_crtc_internal.h"
#include "drm_internal.h"
@@ -141,6 +141,25 @@ static void drm_crtc_unregister_all(struct drm_device *dev)
}
}

+static int drm_crtc_crc_init(struct drm_crtc *crtc)
+{
+#ifdef CONFIG_DEBUG_FS
+ spin_lock_init(&crtc->crc.lock);
+ init_waitqueue_head(&crtc->crc.wq);
+ crtc->crc.source = kstrdup("auto", GFP_KERNEL);
+ if (!crtc->crc.source)
+ return -ENOMEM;
+#endif
+ return 0;
+}
+
+static void drm_crtc_crc_fini(struct drm_crtc *crtc)
+{
+#ifdef CONFIG_DEBUG_FS
+ kfree(crtc->crc.source);
+#endif
+}
+
/**
* drm_crtc_init_with_planes - Initialise a new CRTC object with
* specified primary and cursor planes.
@@ -206,6 +225,12 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
if (cursor)
cursor->possible_crtcs = 1 << drm_crtc_index(crtc);

+ ret = drm_crtc_crc_init(crtc);
+ if (ret) {
+ drm_mode_object_unregister(dev, &crtc->base);
+ return ret;
+ }
+
if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
drm_object_attach_property(&crtc->base, config->prop_active, 0);
drm_object_attach_property(&crtc->base, config->prop_mode_id, 0);
@@ -232,6 +257,8 @@ void drm_crtc_cleanup(struct drm_crtc *crtc)
* the indices on the drm_crtc after us in the crtc_list.
*/

+ drm_crtc_crc_fini(crtc);
+
kfree(crtc->gamma_store);
crtc->gamma_store = NULL;

diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index 1205790ed960..800055c39cdb 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -415,5 +415,37 @@ void drm_debugfs_connector_remove(struct drm_connector *connector)
connector->debugfs_entry = NULL;
}

-#endif /* CONFIG_DEBUG_FS */
+int drm_debugfs_crtc_add(struct drm_crtc *crtc)
+{
+ struct drm_minor *minor = crtc->dev->primary;
+ struct dentry *root;
+ char *name;
+
+ name = kasprintf(GFP_KERNEL, "crtc-%d", crtc->index);
+ if (!name)
+ return -ENOMEM;
+
+ root = debugfs_create_dir(name, minor->debugfs_root);
+ kfree(name);
+ if (!root)
+ return -ENOMEM;
+
+ crtc->debugfs_entry = root;
+
+ if (drm_debugfs_crtc_crc_add(crtc))
+ goto error;

+ return 0;
+
+error:
+ drm_debugfs_crtc_remove(crtc);
+ return -ENOMEM;
+}
+
+void drm_debugfs_crtc_remove(struct drm_crtc *crtc)
+{
+ debugfs_remove_recursive(crtc->debugfs_entry);
+ crtc->debugfs_entry = NULL;
+}
+
+#endif /* CONFIG_DEBUG_FS */
diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
new file mode 100644
index 000000000000..4129405d17c0
--- /dev/null
+++ b/drivers/gpu/drm/drm_debugfs_crc.c
@@ -0,0 +1,351 @@
+/*
+ * Copyright © 2008 Intel Corporation
+ * Copyright © 2016 Collabora Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Based on code from the i915 driver.
+ * Original author: Damien Lespiau <damien.lespiau@intel.com>
+ *
+ */
+
+#include <linux/circ_buf.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <drm/drmP.h>
+
+/**
+ * DOC: CRC ABI
+ *
+ * DRM device drivers can provide to userspace CRC information of each frame as
+ * it reached a given hardware component (a "source").
+ *
+ * Userspace can control generation of CRCs in a given CRTC by writing to the
+ * file dri/0/crtc-N/crc/control in debugfs, with N being the index of the CRTC.
+ * Accepted values are source names (which are driver-specific) and the "auto"
+ * keyword, which will let the driver select a default source of frame CRCs
+ * for this CRTC.
+ *
+ * Once frame CRC generation is enabled, userspace can capture them by reading
+ * the dri/0/crtc-N/crc/data file. Each line in that file contains the frame
+ * number in the first field and then a number of unsigned integer fields
+ * containing the CRC data. Fields are separated by a single space and the number
+ * of CRC fields is source-specific.
+ *
+ * Note that though in some cases the CRC is computed in a specified way and on
+ * the frame contents as supplied by userspace (eDP 1.3), in general the CRC
+ * computation is performed in an unspecified way and on frame contents that have
+ * been already processed in also an unspecified way and thus userspace cannot
+ * rely on being able to generate matching CRC values for the frame contents that
+ * it submits. In this general case, the maximum userspace can do is to compare
+ * the reported CRCs of frames that should have the same contents.
+ */
+
+static int crc_control_show(struct seq_file *m, void *data)
+{
+ struct drm_crtc *crtc = m->private;
+
+ seq_printf(m, "%s\n", crtc->crc.source);
+
+ return 0;
+}
+
+static int crc_control_open(struct inode *inode, struct file *file)
+{
+ struct drm_crtc *crtc = inode->i_private;
+
+ return single_open(file, crc_control_show, crtc);
+}
+
+static ssize_t crc_control_write(struct file *file, const char __user *ubuf,
+ size_t len, loff_t *offp)
+{
+ struct seq_file *m = file->private_data;
+ struct drm_crtc *crtc = m->private;
+ struct drm_crtc_crc *crc = &crtc->crc;
+ char *source;
+
+ if (len == 0)
+ return 0;
+
+ if (len > PAGE_SIZE - 1) {
+ DRM_DEBUG_KMS("Expected < %lu bytes into crtc crc control\n",
+ PAGE_SIZE);
+ return -E2BIG;
+ }
+
+ source = memdup_user_nul(ubuf, len);
+ if (IS_ERR(source))
+ return PTR_ERR(source);
+
+ if (source[len] == '\n')
+ source[len] = '\0';
+
+ spin_lock_irq(&crc->lock);
+
+ if (crc->opened) {
+ spin_unlock_irq(&crc->lock);
+ kfree(source);
+ return -EBUSY;
+ }
+
+ kfree(crc->source);
+ crc->source = source;
+
+ spin_unlock_irq(&crc->lock);
+
+ *offp += len;
+ return len;
+}
+
+const struct file_operations drm_crtc_crc_control_fops = {
+ .owner = THIS_MODULE,
+ .open = crc_control_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+ .write = crc_control_write
+};
+
+static int crtc_crc_open(struct inode *inode, struct file *filep)
+{
+ struct drm_crtc *crtc = inode->i_private;
+ struct drm_crtc_crc *crc = &crtc->crc;
+ struct drm_crtc_crc_entry *entries = NULL;
+ size_t values_cnt;
+ int ret;
+
+ if (crc->opened)
+ return -EBUSY;
+
+ ret = crtc->funcs->set_crc_source(crtc, crc->source, &values_cnt);
+ if (ret)
+ return ret;
+
+ if (WARN_ON(values_cnt > DRM_MAX_CRC_NR)) {
+ ret = -EINVAL;
+ goto err_disable;
+ }
+
+ if (WARN_ON(values_cnt == 0)) {
+ ret = -EINVAL;
+ goto err_disable;
+ }
+
+ entries = kcalloc(DRM_CRC_ENTRIES_NR, sizeof(*entries), GFP_KERNEL);
+ if (!entries) {
+ ret = -ENOMEM;
+ goto err_disable;
+ }
+
+ spin_lock_irq(&crc->lock);
+ crc->entries = entries;
+ crc->values_cnt = values_cnt;
+ crc->opened = true;
+ spin_unlock_irq(&crc->lock);
+
+ return 0;
+
+err_disable:
+ crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
+ return ret;
+}
+
+static int crtc_crc_release(struct inode *inode, struct file *filep)
+{
+ struct drm_crtc *crtc = filep->f_inode->i_private;
+ struct drm_crtc_crc *crc = &crtc->crc;
+ size_t values_cnt;
+
+ spin_lock_irq(&crc->lock);
+ kfree(crc->entries);
+ crc->entries = NULL;
+ crc->head = 0;
+ crc->tail = 0;
+ crc->values_cnt = 0;
+ crc->opened = false;
+ spin_unlock_irq(&crc->lock);
+
+ crtc->funcs->set_crc_source(crtc, NULL, &values_cnt);
+
+ return 0;
+}
+
+static int crtc_crc_data_count(struct drm_crtc_crc *crc)
+{
+ assert_spin_locked(&crc->lock);
+ return CIRC_CNT(crc->head, crc->tail, DRM_CRC_ENTRIES_NR);
+}
+
+/*
+ * 1 frame field of 10 chars plus a number of CRC fields of 10 chars each, space
+ * separated, with a newline at the end and null-terminated.
+ */
+#define LINE_LEN(values_cnt) (10 + 11 * values_cnt + 1 + 1)
+#define MAX_LINE_LEN (LINE_LEN(DRM_MAX_CRC_NR))
+
+static ssize_t crtc_crc_read(struct file *filep, char __user *user_buf,
+ size_t count, loff_t *pos)
+{
+ struct drm_crtc *crtc = filep->f_inode->i_private;
+ struct drm_crtc_crc *crc = &crtc->crc;
+ struct drm_crtc_crc_entry *entry;
+ char buf[MAX_LINE_LEN];
+ int ret, i;
+
+ spin_lock_irq(&crc->lock);
+
+ if (!crc->source) {
+ spin_unlock_irq(&crc->lock);
+ return 0;
+ }
+
+ /* Nothing to read? */
+ while (crtc_crc_data_count(crc) == 0) {
+ if (filep->f_flags & O_NONBLOCK) {
+ spin_unlock_irq(&crc->lock);
+ return -EAGAIN;
+ }
+
+ ret = wait_event_interruptible_lock_irq(crc->wq,
+ crtc_crc_data_count(crc),
+ crc->lock);
+ if (ret) {
+ spin_unlock_irq(&crc->lock);
+ return ret;
+ }
+ }
+
+ /* We know we have an entry to be read */
+ entry = &crc->entries[crc->tail];
+
+ if (count < LINE_LEN(crc->values_cnt)) {
+ spin_unlock_irq(&crc->lock);
+ return -EINVAL;
+ }
+
+ BUILD_BUG_ON_NOT_POWER_OF_2(DRM_CRC_ENTRIES_NR);
+ crc->tail = (crc->tail + 1) & (DRM_CRC_ENTRIES_NR - 1);
+
+ spin_unlock_irq(&crc->lock);
+
+ if (entry->has_frame_counter)
+ sprintf(buf, "0x%08x", entry->frame);
+ else
+ sprintf(buf, "XXXXXXXXXX");
+
+ for (i = 0; i < crc->values_cnt; i++)
+ sprintf(buf + 10 + i * 11, " 0x%08x", entry->crcs[i]);
+ sprintf(buf + 10 + crc->values_cnt * 11, "\n");
+
+ if (copy_to_user(user_buf, buf, LINE_LEN(crc->values_cnt)))
+ return -EFAULT;
+
+ return LINE_LEN(crc->values_cnt);
+}
+
+const struct file_operations drm_crtc_crc_data_fops = {
+ .owner = THIS_MODULE,
+ .open = crtc_crc_open,
+ .read = crtc_crc_read,
+ .release = crtc_crc_release,
+};
+
+/**
+ * drm_debugfs_crtc_crc_add - Add files to debugfs for capture of frame CRCs
+ * @crtc: CRTC to whom the frames will belong
+ *
+ * Adds files to debugfs directory that allows userspace to control the
+ * generation of frame CRCs and to read them.
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
+{
+ struct dentry *crc_ent, *ent;
+
+ if (!crtc->funcs->set_crc_source)
+ return 0;
+
+ crc_ent = debugfs_create_dir("crc", crtc->debugfs_entry);
+ if (!crc_ent)
+ return -ENOMEM;
+
+ ent = debugfs_create_file("control", S_IRUGO, crc_ent, crtc,
+ &drm_crtc_crc_control_fops);
+ if (!ent)
+ goto error;
+
+ ent = debugfs_create_file("data", S_IRUGO, crc_ent, crtc,
+ &drm_crtc_crc_data_fops);
+ if (!ent)
+ goto error;
+
+ return 0;
+
+error:
+ debugfs_remove_recursive(crc_ent);
+
+ return -ENOMEM;
+}
+
+/**
+ * drm_crtc_add_crc_entry - Add entry with CRC information for a frame
+ * @crtc: CRTC to which the frame belongs
+ * @has_frame: whether this entry has a frame number to go with
+ * @frame: number of the frame these CRCs are about
+ * @crcs: array of CRC values, with length matching #drm_crtc_crc.values_cnt
+ *
+ * For each frame, the driver polls the source of CRCs for new data and calls
+ * this function to add them to the buffer from where userspace reads.
+ */
+int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
+ uint32_t frame, uint32_t *crcs)
+{
+ struct drm_crtc_crc *crc = &crtc->crc;
+ struct drm_crtc_crc_entry *entry;
+ int head, tail;
+
+ assert_spin_locked(&crc->lock);
+
+ /* Caller may not have noticed yet that userspace has stopped reading */
+ if (!crc->opened)
+ return -EINVAL;
+
+ head = crc->head;
+ tail = crc->tail;
+
+ if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
+ DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
+ return -ENOBUFS;
+ }
+
+ entry = &crc->entries[head];
+ entry->frame = frame;
+ entry->has_frame_counter = has_frame;
+ memcpy(&entry->crcs, crcs, sizeof(*crcs) * crc->values_cnt);
+
+ head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
+ crc->head = head;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(drm_crtc_add_crc_entry);
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index acf6a5f38920..fa33741746c0 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -206,6 +206,7 @@ static void drm_minor_free(struct drm_device *dev, unsigned int type)
static int drm_minor_register(struct drm_device *dev, unsigned int type)
{
struct drm_minor *minor;
+ struct drm_crtc *crtc;
unsigned long flags;
int ret;

@@ -221,6 +222,14 @@ static int drm_minor_register(struct drm_device *dev, unsigned int type)
return ret;
}

+ if (type == DRM_MINOR_PRIMARY) {
+ drm_for_each_crtc(crtc, dev) {
+ ret = drm_debugfs_crtc_add(crtc);
+ if (ret)
+ DRM_ERROR("DRM: Failed to initialize CRC debugfs.\n");
+ }
+ }
+
ret = device_add(minor->kdev);
if (ret)
goto err_debugfs;
@@ -234,6 +243,10 @@ static int drm_minor_register(struct drm_device *dev, unsigned int type)
return 0;

err_debugfs:
+ if (type == DRM_MINOR_PRIMARY) {
+ drm_for_each_crtc(crtc, dev)
+ drm_debugfs_crtc_remove(crtc);
+ }
drm_debugfs_cleanup(minor);
return ret;
}
@@ -241,12 +254,18 @@ err_debugfs:
static void drm_minor_unregister(struct drm_device *dev, unsigned int type)
{
struct drm_minor *minor;
+ struct drm_crtc *crtc;
unsigned long flags;

minor = *drm_minor_get_slot(dev, type);
if (!minor || !device_is_registered(minor->kdev))
return;

+ if (type == DRM_MINOR_PRIMARY) {
+ drm_for_each_crtc(crtc, dev)
+ drm_debugfs_crtc_remove(crtc);
+ }
+
/* replace @minor with NULL so lookups will fail from now on */
spin_lock_irqsave(&drm_minor_lock, flags);
idr_replace(&drm_minors_idr, NULL, minor->index);
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index b86dc9b921a5..8a1cd8e314c4 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -97,6 +97,9 @@ int drm_debugfs_init(struct drm_minor *minor, int minor_id,
int drm_debugfs_cleanup(struct drm_minor *minor);
int drm_debugfs_connector_add(struct drm_connector *connector);
void drm_debugfs_connector_remove(struct drm_connector *connector);
+int drm_debugfs_crtc_add(struct drm_crtc *crtc);
+void drm_debugfs_crtc_remove(struct drm_crtc *crtc);
+int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc);
#else
static inline int drm_debugfs_init(struct drm_minor *minor, int minor_id,
struct dentry *root)
@@ -116,4 +119,17 @@ static inline int drm_debugfs_connector_add(struct drm_connector *connector)
static inline void drm_debugfs_connector_remove(struct drm_connector *connector)
{
}
+
+static inline int drm_debugfs_crtc_add(struct drm_crtc *crtc)
+{
+ return 0;
+}
+static inline void drm_debugfs_crtc_remove(struct drm_crtc *crtc)
+{
+}
+
+static inline int drm_debugfs_crtc_crc_add(struct drm_crtc *crtc)
+{
+ return 0;
+}
#endif
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 8ca71d66282b..151a90a5ca37 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -42,6 +42,7 @@
#include <drm/drm_connector.h>
#include <drm/drm_encoder.h>
#include <drm/drm_property.h>
+#include <drm/drm_debugfs_crc.h>

struct drm_device;
struct drm_mode_set;
@@ -536,6 +537,30 @@ struct drm_crtc_funcs {
* before data structures are torndown.
*/
void (*early_unregister)(struct drm_crtc *crtc);
+
+ /**
+ * @set_crc_source:
+ *
+ * Changes the source of CRC checksums of frames at the request of
+ * userspace, typically for testing purposes. The sources available are
+ * specific of each driver and a %NULL value indicates that CRC
+ * generation is to be switched off.
+ *
+ * When CRC generation is enabled, the driver should call
+ * drm_crtc_add_crc_entry() at each frame, providing any information
+ * that characterizes the frame contents in the crcN arguments, as
+ * provided from the configured source. Drivers must accept a "auto"
+ * source name that will select a default source for this CRTC.
+ *
+ * This callback is optional if the driver does not support any CRC
+ * generation functionality.
+ *
+ * RETURNS:
+ *
+ * 0 on success or a negative error code on failure.
+ */
+ int (*set_crc_source)(struct drm_crtc *crtc, const char *source,
+ size_t *values_cnt);
};

/**
@@ -652,6 +677,22 @@ struct drm_crtc {
* context.
*/
struct drm_modeset_acquire_ctx *acquire_ctx;
+
+#ifdef CONFIG_DEBUG_FS
+ /**
+ * @debugfs_entry:
+ *
+ * Debugfs directory for this CRTC.
+ */
+ struct dentry *debugfs_entry;
+
+ /**
+ * @crc:
+ *
+ * Configuration settings of CRC capture.
+ */
+ struct drm_crtc_crc crc;
+#endif
};

/**
diff --git a/include/drm/drm_debugfs_crc.h b/include/drm/drm_debugfs_crc.h
new file mode 100644
index 000000000000..7d63b1d4adb9
--- /dev/null
+++ b/include/drm/drm_debugfs_crc.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright © 2016 Collabora Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+#ifndef __DRM_DEBUGFS_CRC_H__
+#define __DRM_DEBUGFS_CRC_H__
+
+#define DRM_MAX_CRC_NR 10
+
+/**
+ * struct drm_crtc_crc_entry - entry describing a frame's content
+ * @has_frame_counter: whether the source was able to provide a frame number
+ * @frame: number of the frame this CRC is about, if @has_frame_counter is true
+ * @crc: array of values that characterize the frame
+ */
+struct drm_crtc_crc_entry {
+ bool has_frame_counter;
+ uint32_t frame;
+ uint32_t crcs[DRM_MAX_CRC_NR];
+};
+
+#define DRM_CRC_ENTRIES_NR 128
+
+/**
+ * struct drm_crtc_crc - data supporting CRC capture on a given CRTC
+ * @lock: protects the fields in this struct
+ * @source: name of the currently configured source of CRCs
+ * @opened: whether userspace has opened the data file for reading
+ * @entries: array of entries, with size of %DRM_CRC_ENTRIES_NR
+ * @head: head of circular queue
+ * @tail: tail of circular queue
+ * @values_cnt: number of CRC values per entry, up to %DRM_MAX_CRC_NR
+ * @wq: workqueue used to synchronize reading and writing
+ */
+struct drm_crtc_crc {
+ spinlock_t lock;
+ const char *source;
+ bool opened;
+ struct drm_crtc_crc_entry *entries;
+ int head, tail;
+ size_t values_cnt;
+ wait_queue_head_t wq;
+};
+
+#if defined(CONFIG_DEBUG_FS)
+int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
+ uint32_t frame, uint32_t *crcs);
+#else
+static inline int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
+ uint32_t frame, uint32_t *crcs)
+{
+ return -EINVAL;
+}
+#endif /* defined(CONFIG_DEBUG_FS) */
+
+#endif /* __DRM_DEBUGFS_CRC_H__ */
--
2.7.4