On Tue, 24 Feb 2026, Mohammed Bilal <[email protected]> wrote:
> Add debugfs interface to expose extended wakeup timeout information for
> DP connectors. This shows whether a retimer is present, the
> current mode (transparent vs non-transparent), and the wakeup timeout
> value in milliseconds.
> This helps verify whether the extended wakeup timeout is functioning
> as expected.
>
> Signed-off-by: Mohammed Bilal <[email protected]>
Do we really have to add debugfs for things that are just DPCD reads? We
have the DP AUX device exposed, and a userspace tool could read all of
this through that. It's much more pain to maintain this in the kernel.
BR,
Jani.
> ---
> .../drm/i915/display/intel_display_debugfs.c | 78 +++++++++++++++++++
> 1 file changed, 78 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index 2614c4863c87..292ee71643da 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -1310,6 +1310,78 @@ static const struct file_operations i915_joiner_fops =
> {
> .write = i915_joiner_write
> };
>
> +static int i915_extended_wakeup_timeout_show(struct seq_file *m, void *data)
> +{
> + struct intel_connector *connector = m->private;
> + struct intel_display *display = to_intel_display(connector);
> + struct intel_encoder *encoder = intel_attached_encoder(connector);
> + struct intel_dp *intel_dp;
> + bool retimer_present = false;
> + bool transparent_mode = true;
> + int wakeup_timeout_ms = 1;
> + int lttpr_count;
> + u8 val;
> + int ret;
> +
> + if (!encoder)
> + return -ENODEV;
> +
> + ret =
> drm_modeset_lock_single_interruptible(&display->drm->mode_config.connection_mutex);
> + if (ret)
> + return ret;
> + if (connector->base.status != connector_status_connected) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + intel_dp = enc_to_intel_dp(encoder);
> + lttpr_count = drm_dp_lttpr_count(intel_dp->lttpr_common_caps);
> + retimer_present = (lttpr_count > 0);
> + transparent_mode = intel_dp_lttpr_transparent_mode_enabled(intel_dp);
> +
> + if (transparent_mode) {
> + ret = drm_dp_dpcd_read_data(&intel_dp->aux,
> +
> DP_EXTENDED_DPRX_SLEEP_WAKE_TIMEOUT_REQUEST,
> + &val, 1);
> + if (!ret) {
> + static const u8 timeout_mapping[] = {
> + [DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_1_MS] = 1,
> + [DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_20_MS] = 20,
> + [DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_40_MS] = 40,
> + [DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_60_MS] = 60,
> + [DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_80_MS] = 80,
> + [DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_100_MS] =
> 100,
> + };
> +
> + if (val < ARRAY_SIZE(timeout_mapping) &&
> timeout_mapping[val])
> + wakeup_timeout_ms = timeout_mapping[val];
> + }
> + } else {
> + ret = drm_dp_dpcd_read_data(&intel_dp->aux,
> +
> DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT,
> + &val, 1);
> +
> + if (!ret) {
> +
> + int timeout_val = val &
> DP_EXTENDED_WAKE_TIMEOUT_REQUEST_MASK;
> +
> + wakeup_timeout_ms = timeout_val ? (timeout_val * 10) :
> 1;
> + }
> + }
> +
> + if (ret)
> + wakeup_timeout_ms = -1;
> +
> + seq_printf(m, "retimer_present: %s\n", retimer_present ? "yes" : "no");
> + seq_printf(m, "mode: %s\n", transparent_mode ? "transparent" :
> "non-transparent");
> + seq_printf(m, "wakeup_timeout_ms: %d\n", wakeup_timeout_ms);
> +
> +out:
> + drm_modeset_unlock(&display->drm->mode_config.connection_mutex);
> + return ret;
> +}
> +DEFINE_SHOW_ATTRIBUTE(i915_extended_wakeup_timeout);
> +
> /**
> * intel_connector_debugfs_add - add i915 specific connector debugfs files
> * @connector: pointer to a registered intel_connector
> @@ -1335,6 +1407,12 @@ void intel_connector_debugfs_add(struct
> intel_connector *connector)
> intel_dp_link_training_debugfs_add(connector);
> intel_link_bw_connector_debugfs_add(connector);
>
> + if (DISPLAY_VER(display) >= 30 &&
> + connector_type == DRM_MODE_CONNECTOR_DisplayPort &&
> !connector->mst.dp) {
> + debugfs_create_file("i915_extended_wakeup_timeout", 0444, root,
> + connector,
> &i915_extended_wakeup_timeout_fops);
> + }
> +
> if (DISPLAY_VER(display) >= 11 &&
> ((connector_type == DRM_MODE_CONNECTOR_DisplayPort &&
> !connector->mst.dp) ||
> connector_type == DRM_MODE_CONNECTOR_eDP)) {
--
Jani Nikula, Intel
