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@xilinx.com Signed-off-by: Hyun Kwon hyun.kwon@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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