Re: [PATCH 05/10] drm/i915: Add debugfs interface for Displayport debug and compliance testing

Daniel Vetter
2014-10-23T12:50:42Z

Hi Tood,

Paulo already mentioned it, so I'll just rehash quickly: I think the
points from the internal pre-review first need to be address before we can
dig into details. I know that the discussion there pettered out a bit, but
imo it's the patch authors responsibility to pick that up again and ping
people. One example I've noticed is the use of signals: We really want a
pollable file in debugfs (see e.g. the crc stuff). You can always still
redirect that to give you a signal, although I highly recommend to avoid
signals like the plague - they're simply too much a pain.

But now onto the real comment I wanted to make, see below.

On Thu, Oct 09, 2014 at 08:38:05AM -0700, Todd Previte wrote:
> Adds an interface that allows for Displayport configuration information to be accessed
> through debugfs. The information paramters provided here are as follows:
> Link rate
> Lane count
> Bits per pixel
> Voltage swing level
> Preemphasis level
> Display mode
>
> These parameters are intended to be used by userspace applications that need access
> to the link configuration of any active Displayport connection. Additionally,
> applications can make adjustments to these parameters through this interface to
> allow userspace application to have fine-grained control over link training
> paramters.
>
> Signed-off-by: Todd Previte <tprevite@gmail.com>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 389 ++++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_dp.c | 13 +-
> 2 files changed, 397 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index da4036d..2dada18 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -33,6 +33,7 @@
> #include <linux/slab.h>
> #include <linux/export.h>
> #include <linux/list_sort.h>
> +#include <linux/string.h>
> #include <asm/msr-index.h>
> #include <drm/drmP.h>
> #include "intel_drv.h"
> @@ -51,6 +52,46 @@ static const char *yesno(int v)
> return v ? "yes" : "no";
> }
>
> +#define DP_PARAMETER_COUNT 8
> +#define MAX_DP_CONFIG_LINE_COUNT 64
> +
> +enum dp_config_param {
> + DP_CONFIG_PARAM_INVALID = -1,
> + DP_CONFIG_PARAM_CONNECTOR = 0,
> + DP_CONFIG_PARAM_LINK_RATE,
> + DP_CONFIG_PARAM_LANE_COUNT,
> + DP_CONFIG_PARAM_VOLTAGE_SWING,
> + DP_CONFIG_PARAM_PREEMPHASIS,
> + DP_CONFIG_PARAM_HRES,
> + DP_CONFIG_PARAM_VRES,
> + DP_CONFIG_PARAM_BPP
> +};

I think it's better to expose this as drm properties on the DP connector.
This has a pile of upsides:
- We don't need to invent a new parser.
- Users can play with them to test out different theories.
- We could even use this to fix broken panels/boards without vbt or
anything using our plan to set up the initial config with a dt firmware
blob.

So would be a lot more useful than this private interface.

For the properties themselves I think we should go with explicit
enumerations with default value "automatic" and then an enumeration of all
values allowed by DP. For the naming of the properties I guess something
like DP_link_lanes, DP_link_clock, ... would look pretty. The properties
should be in dev->mode_config (since they're reallly generic) and I think
we want one function to register them all in one go in the drm_dp_helper.c
library. Maybe we could even put the values into the existing dp source
struct so that we don't have to reinvent the decode logic every single
time.

Now on the properties themselves I think they all make perfect sense
except:
- bpp: I've thought if we define lanes+clock plus the bpp from the
framebuffer (we support 16bpp, 24bpp, 30bpp and 48bpp) we should be able
to hit every possible combination. So I wonder in which precise
corner-case the userspace program can't set up the link like it wants to
without the bpp property.
- hres/vres: Seem unused and look like they're back from an earlier
design. We should be able to set that through the mode we're setting
with setCrtc.

With that plus Paulo&Jesse's internal comments addressed I think this is
moving into the right direction. Aside (probably just missed it): Where's
the userspace side of this?

Thanks, Daniel

> +
> +struct dp_config {
> + enum dp_config_param type;
> + unsigned long value;
> +};
> +
> +const char *dp_conf_tokens[DP_PARAMETER_COUNT] = {
> + "Connector",
> + "Link Rate",
> + "Lane Count",
> + "Voltage Swing Level",
> + "Preemphasis Level",
> + "Horizontal Resolution",
> + "Vertical Resolution",
> + "Bits Per Pixel"
> +};
> +/* Strings for writing out dp_configs */
> +#define DP_CONF_STR_CONNECTOR "Connector: %s\n"
> +#define DP_CONF_STR_LINKRATE "Link Rate: %02x\n"
> +#define DP_CONF_STR_LANES "Lane Count: %u\n"
> +#define DP_CONF_STR_VSWING "Voltage Swing Level: %u\n"
> +#define DP_CONF_STR_PREEMP "Preemphasis Level: %u\n"
> +#define DP_CONF_STR_HRES "Horizontal Resolution: %d\n"
> +#define DP_CONF_STR_VRES "Vertical Resolution: %d\n"
> +#define DP_CONF_STR_BPP "Bits Per Pixel: %u\n"
> +
> /* As the drm_debugfs_init() routines are called before dev->dev_private is
> * allocated we need to hook into the minor for release. */
> static int
> @@ -3505,6 +3546,353 @@ static const struct file_operations i915_display_crc_ctl_fops = {
> .write = display_crc_ctl_write
> };
>
> +static void displayport_show_config_info(struct seq_file *m,
> + struct intel_connector *intel_connector)
> +{
> + struct intel_encoder *intel_encoder = intel_connector->encoder;
> + struct intel_dp *intel_dp;
> + struct intel_crtc *icrtc;
> + int pipe_bpp, hres, vres;
> + uint8_t vs[4], pe[4];
> + struct drm_display_mode *mode;
> + int i = 0;
> +
> + if (intel_encoder) {
> + intel_dp = enc_to_intel_dp(&intel_encoder->base);
> + for (i = 0; i < intel_dp->lane_count; i++) {
> + vs[i] = intel_dp->train_set[i]
> + & DP_TRAIN_VOLTAGE_SWING_MASK;
> + pe[i] = (intel_dp->train_set[i]
> + & DP_TRAIN_PRE_EMPHASIS_MASK) >> 3;
> + }
> + if (intel_encoder->type == INTEL_OUTPUT_DISPLAYPORT) {
> + if (intel_encoder->new_crtc) {
> + pipe_bpp = intel_encoder->new_crtc->config.pipe_bpp;
> + mode = &intel_encoder->new_crtc->config.adjusted_mode;
> + hres = mode->hdisplay;
> + vres = mode->vdisplay;
> + } else if (intel_encoder->base.crtc) {
> + icrtc = to_intel_crtc(intel_encoder->base.crtc);
> + pipe_bpp = icrtc->config.pipe_bpp;
> + mode = &icrtc->config.adjusted_mode;
> + hres = mode->hdisplay;
> + vres = mode->vdisplay;
> + } else {
> + pipe_bpp = 0;
> + hres = vres = 0;
> + }
> + seq_printf(m, DP_CONF_STR_CONNECTOR,
> + intel_connector->base.name);
> + seq_printf(m, DP_CONF_STR_LINKRATE, intel_dp->link_bw);
> + seq_printf(m, DP_CONF_STR_LANES, intel_dp->lane_count);
> + seq_printf(m, DP_CONF_STR_VSWING, vs[0]);
> + seq_printf(m, DP_CONF_STR_PREEMP, pe[0]);
> + seq_printf(m, DP_CONF_STR_HRES, hres);
> + seq_printf(m, DP_CONF_STR_VRES, vres);
> + seq_printf(m, DP_CONF_STR_BPP, pipe_bpp);
> + }
> + }
> +}
> +
> +enum dp_config_param displayport_get_config_param_type(char *input_string)
> +{
> + enum dp_config_param param_type = DP_CONFIG_PARAM_INVALID;
> + int i = 0;
> +
> + for (i = 0; i < DP_PARAMETER_COUNT; i++) {
> + if (strncmp(input_string, dp_conf_tokens[i],
> + strlen(dp_conf_tokens[i])) == 0) {
> + param_type = (enum dp_config_param) i;
> + break;
> + }
> + }
> + return param_type;
> +}
> +
> +int value_for_config_param(enum dp_config_param param,
> + char *input_string,
> + void *output_value)
> +{
> + int status = 0;
> + unsigned int *out_ptr = (unsigned int *)output_value;
> + char *index = input_string;
> +
> + switch (param) {
> + case DP_CONFIG_PARAM_CONNECTOR:
> + output_value = (char *)index;
> + break;
> + case DP_CONFIG_PARAM_LINK_RATE:
> + case DP_CONFIG_PARAM_LANE_COUNT:
> + case DP_CONFIG_PARAM_VOLTAGE_SWING:
> + case DP_CONFIG_PARAM_PREEMPHASIS:
> + status = kstrtol(index, 16, (long *)out_ptr);
> + break;
> + case DP_CONFIG_PARAM_HRES:
> + case DP_CONFIG_PARAM_VRES:
> + case DP_CONFIG_PARAM_BPP:
> + status = kstrtol(index, 10, (long *)out_ptr);
> + break;
> + default:
> + /* Unhandled case */
> + status = -EINVAL;
> + *out_ptr = 0;
> + break;
> + }
> +
> + return status;
> +}
> +
> +int tokenize_dp_config(char *input_buffer, char *output[])
> +{
> + char *base = input_buffer, *index, *end;
> + int line_count = 0;
> + int i = 0, len = 0;
> + int done = 0;
> +
> + if (!input_buffer)
> + return 0;
> +
> + while (!done) {
> + index = strpbrk(base, ":");
> + if (index) {
> + len = index - base;
> + *index = '\0';
> + index++;
> + /* Save the type string */
> + output[i] = base;
> + i++;
> + line_count++;
> + end = strpbrk(index, "\n\0");
> + if (end) {
> + *end = '\0';
> + /* Eat up whitespace */
> + while (*index <= 0x20)
> + index++;
> + output[i] = index;
> + i++;
> + line_count++;
> + } else
> + done = 1;
> + /* Move to the next section of the string */
> + base = end + 1;
> + } else
> + done = 1;
> + }
> + return line_count;
> +}
> +
> +static int displayport_parse_config(char *input_buffer,
> + ssize_t buffer_size,
> + struct intel_dp_link_config *dp_conf)
> +{
> + int status = 0;
> + char *lines[MAX_DP_CONFIG_LINE_COUNT];
> + int i = 0;
> + struct dp_config parms[DP_PARAMETER_COUNT];
> + int line_count = 0;
> + char *buffer = input_buffer;
> + enum dp_config_param parm_type;
> + unsigned long parm_value;
> +
> + line_count = tokenize_dp_config(buffer, lines);
> +
> + if (line_count == 0) {
> + DRM_DEBUG_DRIVER("No lines to process\n");
> + return 0;
> + }
> +
> + for (i = 0; i < line_count; i += 2) {
> + parm_type = displayport_get_config_param_type(lines[i]);
> + if (parm_type != DP_CONFIG_PARAM_INVALID) {
> + status = value_for_config_param(parm_type,
> + lines[i+1],
> + &parm_value);
> + if (status == 0) {
> + parms[parm_type].type = parm_type;
> + parms[parm_type].value = parm_value;
> + }
> + }
> + }
> +
> + for (i = 1; i < DP_PARAMETER_COUNT; i++)
> + DRM_DEBUG_DRIVER("%s = %lu\n",
> + dp_conf_tokens[parms[i].type],
> + parms[i].value);
> +
> + /* Validate any/all incoming parameters */
> + strcpy(dp_conf->connector_name,
> + (char *)parms[DP_CONFIG_PARAM_CONNECTOR].value);
> +
> + if (parms[DP_CONFIG_PARAM_LINK_RATE].value == 0x06 ||
> + parms[DP_CONFIG_PARAM_LINK_RATE].value == 0x0a ||
> + parms[DP_CONFIG_PARAM_LINK_RATE].value == 0x14) {
> + dp_conf->link_rate =
> + parms[DP_CONFIG_PARAM_LINK_RATE].value;
> + } else
> + return -EINVAL;
> +
> + if (parms[DP_CONFIG_PARAM_LANE_COUNT].value == 0x01 ||
> + parms[DP_CONFIG_PARAM_LANE_COUNT].value == 0x02 ||
> + parms[DP_CONFIG_PARAM_LANE_COUNT].value == 0x04) {
> + dp_conf->lane_count =
> + parms[DP_CONFIG_PARAM_LANE_COUNT].value;
> + } else
> + return -EINVAL;
> +
> + if (parms[DP_CONFIG_PARAM_VOLTAGE_SWING].value <= 0x03 &&
> + parms[DP_CONFIG_PARAM_VOLTAGE_SWING].value >= 0x00) {
> + dp_conf->vswing_level =
> + parms[DP_CONFIG_PARAM_VOLTAGE_SWING].value;
> + } else
> + return -EINVAL;
> +
> + if (parms[DP_CONFIG_PARAM_PREEMPHASIS].value <= 0x03 &&
> + parms[DP_CONFIG_PARAM_PREEMPHASIS].value >= 0x00) {
> + dp_conf->preemp_level =
> + parms[DP_CONFIG_PARAM_PREEMPHASIS].value;
> + } else
> + return -EINVAL;
> +
> + if (parms[DP_CONFIG_PARAM_BPP].value == 18 ||
> + parms[DP_CONFIG_PARAM_BPP].value == 24 ||
> + parms[DP_CONFIG_PARAM_BPP].value == 30 ||
> + parms[DP_CONFIG_PARAM_BPP].value == 36) {
> + dp_conf->bits_per_pixel =
> + parms[DP_CONFIG_PARAM_PREEMPHASIS].value;
> + } else
> + return -EINVAL;
> +
> + if (parms[DP_CONFIG_PARAM_HRES].value > 0 &&
> + parms[DP_CONFIG_PARAM_HRES].value <= 8192) {
> + dp_conf->hres =
> + parms[DP_CONFIG_PARAM_HRES].value;
> + } else
> + return -EINVAL;
> +
> + if (parms[DP_CONFIG_PARAM_VRES].value > 0 &&
> + parms[DP_CONFIG_PARAM_VRES].value <= 8192) {
> + dp_conf->vres =
> + parms[DP_CONFIG_PARAM_VRES].value;
> + } else
> + return -EINVAL;
> +
> + return status;
> +}
> +
> +static int displayport_config_ctl_show(struct seq_file *m, void *data)
> +{
> + struct drm_device *dev = m->private;
> + struct drm_connector *connector;
> + struct intel_encoder *intel_encoder;
> + struct intel_connector *intel_connector;
> +
> + if (!dev)
> + return -ENODEV;
> +
> + list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
> + intel_connector = to_intel_connector(connector);
> + intel_encoder = intel_connector->encoder;
> + if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
> + if (intel_encoder->type == INTEL_OUTPUT_DISPLAYPORT ||
> + intel_encoder->type == INTEL_OUTPUT_UNKNOWN) {
> + if (connector->status == connector_status_connected) {
> + displayport_show_config_info(m, intel_connector);
> + } else {
> + seq_printf(m, DP_CONF_STR_CONNECTOR,
> + intel_connector->base.name);
> + seq_printf(m, "disconnected\n");
> + }
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int displayport_config_ctl_open(struct inode *inode,
> + struct file *file)
> +{
> + struct drm_device *dev = inode->i_private;
> +
> + return single_open(file, displayport_config_ctl_show, dev);
> +}
> +
> +static ssize_t displayport_config_ctl_write(struct file *file,
> + const char __user *ubuf,
> + size_t len, loff_t *offp)
> +{
> + char *input_buffer;
> + int status = 0;
> + struct seq_file *m;
> + struct drm_device *dev;
> + struct drm_connector *connector;
> + struct intel_encoder *intel_encoder;
> + struct intel_connector *intel_connector;
> + struct intel_dp *intel_dp;
> + struct intel_dp_link_config dp_conf;
> +
> + m = file->private_data;
> + if (!m) {
> + status = -ENODEV;
> + return status;
> + }
> + dev = m->private;
> +
> + if (!dev) {
> + status = -ENODEV;
> + return status;
> + }
> +
> + if (len == 0)
> + return 0;
> +
> + input_buffer = kmalloc(len + 1, GFP_KERNEL);
> + if (!input_buffer)
> + return -ENOMEM;
> +
> + if (copy_from_user(input_buffer, ubuf, len)) {
> + status = -EFAULT;
> + goto out;
> + }
> +
> + input_buffer[len] = '\0';
> + memset(&dp_conf, 0, sizeof(struct intel_dp_link_config));
> + DRM_DEBUG_DRIVER("Copied %d bytes from user\n", (unsigned int)len);
> + status = displayport_parse_config(input_buffer, len, &dp_conf);
> +
> + list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
> + intel_connector = to_intel_connector(connector);
> + intel_encoder = intel_connector->encoder;
> + if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
> + if (intel_encoder->type == INTEL_OUTPUT_DISPLAYPORT ||
> + intel_encoder->type == INTEL_OUTPUT_UNKNOWN) {
> + intel_dp = enc_to_intel_dp(&intel_encoder->base);
> + memcpy(&intel_dp->compliance_config,
> + &dp_conf,
> + sizeof(struct intel_dp_link_config));
> + }
> + }
> + }
> +
> +
> +out:
> + kfree(input_buffer);
> + if (status < 0)
> + return status;
> +
> + *offp += len;
> + return len;
> +}
> +
> +static const struct file_operations i915_displayport_config_ctl_fops = {
> + .owner = THIS_MODULE,
> + .open = displayport_config_ctl_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> + .write = displayport_config_ctl_write
> +};
> +
> static void wm_latency_show(struct seq_file *m, const uint16_t wm[5])
> {
> struct drm_device *dev = m->private;
> @@ -4208,6 +4596,7 @@ static const struct i915_debugfs_files {
> {"i915_spr_wm_latency", &i915_spr_wm_latency_fops},
> {"i915_cur_wm_latency", &i915_cur_wm_latency_fops},
> {"i915_fbc_false_color", &i915_fbc_fc_fops},
> + {"i915_displayport_config_ctl", &i915_displayport_config_ctl_fops}
> };
>
> void intel_display_crc_init(struct drm_device *dev)
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index a7acc61..b3ddd15 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3968,7 +3968,7 @@ intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
> static uint8_t
> intel_dp_autotest_link_training(struct intel_dp *intel_dp)
> {
> - uint8_t test_result = DP_TEST_NAK;
> + uint8_t test_result = DP_TEST_ACK;
> return test_result;
> }
>
> @@ -4013,21 +4013,25 @@ intel_dp_handle_test_request(struct intel_dp *intel_dp)
> DRM_DEBUG_KMS("Executing LINK_TRAINING request\n");
> intel_dp->compliance_test_data = DP_TEST_LINK_TRAINING;
> response = intel_dp_autotest_link_training(intel_dp);
> + status = intel_dp_signal_userspace(intel_dp);
> break;
> case DP_TEST_LINK_VIDEO_PATTERN:
> DRM_DEBUG_KMS("Executing TEST_PATTERN request\n");
> intel_dp->compliance_test_data = DP_TEST_LINK_VIDEO_PATTERN;
> response = intel_dp_autotest_video_pattern(intel_dp);
> + status = intel_dp_signal_userspace(intel_dp);
> break;
> case DP_TEST_LINK_EDID_READ:
> DRM_DEBUG_KMS("Executing EDID request\n");
> intel_dp->compliance_test_data = DP_TEST_LINK_EDID_READ;
> response = intel_dp_autotest_edid(intel_dp);
> + status = intel_dp_signal_userspace(intel_dp);
> break;
> case DP_TEST_LINK_PHY_TEST_PATTERN:
> DRM_DEBUG_KMS("Executing PHY_PATTERN request\n");
> intel_dp->compliance_test_data = DP_TEST_LINK_PHY_TEST_PATTERN;
> response = intel_dp_autotest_phy_pattern(intel_dp);
> + status = intel_dp_signal_userspace(intel_dp);
> break;
> /* FAUX is optional in DP 1.2*/
> case DP_TEST_LINK_FAUX_PATTERN:
> @@ -4038,10 +4042,9 @@ intel_dp_handle_test_request(struct intel_dp *intel_dp)
> DRM_DEBUG_KMS("Unhandled test request\n");
> break;
> }
> - if (status != 0) {
> - response = DP_TEST_NAK;
> - DRM_DEBUG_KMS("Error %d processing test request\n", status);
> - }
> + if (status != 0)
> + DRM_DEBUG_KMS("Status code %d processing test request\n",
> + status);
> status = drm_dp_dpcd_write(&intel_dp->aux,
> DP_TEST_RESPONSE,
> &response, 1);
> --
> 1.9.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch