[PATCH 1/1] drm/dp: Add debufs support for DP dpcd log
Tejas Upadhyay
tejas.upadhyay at xilinx.com
Tue Jul 31 12:39:26 UTC 2018
Patch adds support for debugging DisplayPort :
* All dpcd read/write transactions are logged
* Logging done per AUX interface
* Use following command to to list AUX transactions:
bash # cat /sys/kernel/debug/drm_dp_aux/$AUXNAME
@0x0000: 0x12
@0x0001: 0x14
@0x0002: 0xc4
@0x0003: 0x01
@0x0004: 0x01
@0x0005: 0x01
@0x0006: 0x01
@0x0007: 0x81
@0x0008: 0x02
@0x0009: 0x02
@0x000a: 0x06
@0x000b: 0x00
@0x000c: 0x00
@0x000d: 0x00
@0x000e: 0x00
@0x0100: 0x14
@0x0101: 0x82
@0x0102: 0x00
@0x0103: 0x0a
@0x0104: 0x0a
@0x0107: 0x10
@0x0108: 0x01
@0x0202: 0x77
@0x0203: 0x00
@0x0204: 0x01
@0x0205: 0x02
@0x0206: 0x66
@0x0207: 0x00
Above information will help to debug DisplayPort related runtime issues
knowing what communication was done between DisplayPort sink and source.
Signed-off-by: Tejas Upadhyay <tejas.upadhyay at xilinx.com>
Signed-off-by: Hyun Kwon <hyun.kwon at xilinx.com>
---
drivers/gpu/drm/Kconfig | 10 +++
drivers/gpu/drm/drm_dp_helper.c | 174 +++++++++++++++++++++++++++++++++++++++-
include/drm/drm_dp_helper.h | 7 ++
3 files changed, 190 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index f3c71e3..bb16e24 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -34,6 +34,16 @@ config DRM_DP_AUX_CHARDEV
read and write values to arbitrary DPCD registers on the DP aux
channel.
+config DRM_DEBUG_DP
+ bool "DRM dp debug helper"
+ default n
+ depends on DRM
+ help
+ Choose this option to enable a debugfs functionality for drm-dp.
+ Will help in debugging display port related issue.
+ Recommended for driver developer as well as tester.
+ Say "Y" to enable debug support.
+
config DRM_DEBUG_MM
bool "Insert extra checks and debug info into the DRM range managers"
default n
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 08af8d6..e8be361 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -28,6 +28,9 @@
#include <linux/sched.h>
#include <linux/i2c.h>
#include <linux/seq_file.h>
+#ifdef CONFIG_DRM_DEBUG_DP
+#include <linux/debugfs.h>
+#endif
#include <drm/drm_dp_helper.h>
#include <drm/drmP.h>
@@ -57,6 +60,171 @@ static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],
return (l >> s) & 0xf;
}
+#ifdef CONFIG_DRM_DEBUG_DP
+
+static uint drm_dp_debugfs_dpcd_size = 0x5ff;
+module_param_named(debugfs_dpcd_size, drm_dp_debugfs_dpcd_size, uint, 0444);
+MODULE_PARM_DESC(debugfs_dpcd_size, "Debugfs DPCD buffer size (default: 1544)");
+
+static struct dentry *root;
+
+static bool drm_dp_debugfs_bitmap_is_set(struct drm_dp_aux *aux,
+ unsigned int pos)
+{
+ u8 byte, bit;
+
+ byte = pos / 8;
+ bit = pos % 8;
+
+ return !!(aux->dpcd_bitmap[byte] & BIT(bit));
+}
+
+static void drm_dp_debugfs_bitmap_set(struct drm_dp_aux *aux, unsigned int pos)
+{
+ u8 byte, bit;
+
+ byte = pos / 8;
+ bit = pos % 8;
+ aux->dpcd_bitmap[byte] |= BIT(bit);
+}
+
+/* DP debugfs read API, to be called by user app */
+static ssize_t drm_dp_debugfs_read(struct file *f, char __user *buf,
+ size_t size, loff_t *pos)
+{
+ struct drm_dp_aux *aux = (struct drm_dp_aux *)f->f_inode->i_private;
+ char *kern_buff = NULL;
+ unsigned int i;
+ size_t kern_buff_len;
+ int err;
+
+ if (size <= 0)
+ return -EINVAL;
+ if (*pos != 0)
+ return 0;
+
+ kern_buff_len = size;
+ kern_buff = kzalloc(kern_buff_len, GFP_KERNEL);
+ if (!kern_buff)
+ return -ENOMEM;
+
+ for (i = 0; i < drm_dp_debugfs_dpcd_size; i++) {
+ if (drm_dp_debugfs_bitmap_is_set(aux, i)) {
+ char str[16] = "";
+
+ sprintf(str, "@0x%04x: 0x%02x\n", i, aux->dpcd_data[i]);
+ if (kern_buff_len < strlen(str))
+ break;
+
+ strcat(kern_buff, str);
+ kern_buff_len -= strlen(str);
+ }
+ }
+ kern_buff_len = strlen(kern_buff);
+ size = min(size, kern_buff_len);
+ err = copy_to_user(buf, kern_buff, size);
+ kfree(kern_buff);
+ if (err)
+ return err;
+ *pos = size + 1;
+
+ return size;
+}
+
+static const struct file_operations fops_drm_dp_dbgfs = {
+ .owner = THIS_MODULE,
+ .read = drm_dp_debugfs_read,
+};
+
+static int drm_dp_debugfs_init(struct drm_dp_aux *aux)
+{
+ struct dentry *entry;
+ u8 *bitmap, *data;
+ int err;
+
+ /* FIXME: better be under drm debugfs dir, and cleaned up properly */
+ if (!root) {
+ root = debugfs_create_dir("drm_dp_aux", NULL);
+ if (!root) {
+ DRM_ERROR("debugfs_create_dir failed for root\n");
+ return -ENODEV;
+ }
+ }
+
+ /* FIXME: There may be a better name than the aux name */
+ entry = debugfs_create_file(aux->name, 0444, root, aux,
+ &fops_drm_dp_dbgfs);
+ if (!entry) {
+ DRM_ERROR("debugfs_create_file testcase failed\n");
+ err = -ENODEV;
+ goto err_dbgfs;
+ }
+
+ bitmap = devm_kzalloc(aux->dev,
+ sizeof(*bitmap) * (drm_dp_debugfs_dpcd_size / 8),
+ GFP_KERNEL);
+ if (unlikely(!bitmap)) {
+ err = -ENOMEM;
+ goto err_dbgfs;
+ }
+
+ data = devm_kzalloc(aux->dev, sizeof(*data) * drm_dp_debugfs_dpcd_size,
+ GFP_KERNEL);
+ if (unlikely(!data)) {
+ err = -ENOMEM;
+ goto err_dbgfs;
+ }
+
+ aux->dpcd_data = data;
+ aux->dpcd_bitmap = bitmap;
+
+ return 0;
+
+err_dbgfs:
+ debugfs_remove_recursive(entry);
+ return err;
+}
+
+/* Deinit DP debugfs */
+static void drm_dp_debugfs_deinit(struct drm_dp_aux *aux)
+{
+ struct dentry *entry;
+
+ entry = debugfs_lookup(aux->name, root);
+ debugfs_remove_recursive(entry);
+}
+
+static void drm_dp_debugfs_log(struct drm_dp_aux *aux,
+ struct drm_dp_aux_msg *msg)
+{
+ u8 *buf;
+ unsigned int i;
+
+ buf = (u8 *)msg->buffer;
+ for (i = 0; i < msg->size; i++) {
+ aux->dpcd_data[msg->address + i] = buf[i];
+ drm_dp_debugfs_bitmap_set(aux, msg->address + i);
+ }
+}
+
+#else
+
+static void drm_dp_debugfs_log(struct drm_dp_aux *aux,
+ struct drm_dp_aux_msg *msg)
+{
+}
+
+static int drm_dp_debugfs_init(struct drm_dp_aux *aux)
+{
+ return 0;
+}
+
+static void drm_dp_debugfs_deinit(struct drm_dp_aux *aux)
+{
+}
+
+#endif
+
bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
@@ -229,6 +397,8 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
ret = err;
unlock:
+ /* Log dpcd aux write transactions*/
+ drm_dp_debugfs_log(aux, &msg);
mutex_unlock(&aux->hw_mutex);
return ret;
}
@@ -1108,7 +1278,8 @@ int drm_dp_aux_register(struct drm_dp_aux *aux)
drm_dp_aux_unregister_devnode(aux);
return ret;
}
-
+ /* Init DP debufs*/
+ drm_dp_debugfs_init(aux);
return 0;
}
EXPORT_SYMBOL(drm_dp_aux_register);
@@ -1119,6 +1290,7 @@ EXPORT_SYMBOL(drm_dp_aux_register);
*/
void drm_dp_aux_unregister(struct drm_dp_aux *aux)
{
+ drm_dp_debugfs_deinit(aux);
drm_dp_aux_unregister_devnode(aux);
i2c_del_adapter(&aux->ddc);
}
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index b17476a..442dfb8 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -962,6 +962,8 @@ struct drm_dp_aux_msg {
* @crc_work: worker that captures CRCs for each frame
* @crc_count: counter of captured frame CRCs
* @transfer: transfers a message representing a single AUX transaction
+ * @dpcd_data: store aux transactions for dp debugfs
+ * @dpcd_bitmap: store a bitmap for valid dpcd data
*
* The .dev field should be set to a pointer to the device that implements
* the AUX channel.
@@ -1010,6 +1012,11 @@ struct drm_dp_aux {
* @i2c_defer_count: Counts I2C DEFERs, used for DP validation.
*/
unsigned i2c_defer_count;
+#ifdef CONFIG_DRM_DEBUG_DP
+ /* aux transactions for dp debugfs*/
+ u8 *dpcd_data;
+ u8 *dpcd_bitmap;
+#endif
};
ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
--
2.7.4
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