On Fri, 07 Feb 2025, Suraj Kandpal <suraj.kandpal@xxxxxxxxx> wrote:
> Testing HDCP 1.4 becomes tough since the only way our code comes to
> HDCP 1.4 pathway is if the monitor only supports HDCP 1.4 which
> becomes tough to find sometimes.
> Setting this debug_fs entry will force use to use the HDCP 1.4 path
> so that more robust HDCP 1.4 testing can take place.
For several years now the direction has been to move and place the
debugfs handling next to the implementation, instead of piling on in
intel_display_debugfs.c. It's been happening gradually.
It's time to draw a line in the sand. I'm not accepting any new code in
intel_display_debugfs.c, including this one. It needs to move.
I've rebased and reposted an old patch to move hdcp debugfs to
intel_hdcp.c. After that, this needs to go to intel_hdcp.c.
Some other comments inline.
> Signed-off-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
> ---
> .../drm/i915/display/intel_display_debugfs.c | 76 +++++++++++++++++++
> .../drm/i915/display/intel_display_types.h | 2 +
> drivers/gpu/drm/i915/display/intel_hdcp.c | 2 +-
> 3 files changed, 79 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index 926f09c35084..1b34aed98849 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -1383,6 +1383,80 @@ static const struct file_operations i915_joiner_fops = {
> .write = i915_joiner_write
> };
>
> +static ssize_t i915_force_hdcp14_write(struct file *file,
> + const char __user *ubuf,
> + size_t len, loff_t *offp)
> +{
> + struct seq_file *m = file->private_data;
> + struct intel_connector *connector = m->private;
> + struct intel_display *display = to_intel_display(connector);
> + struct intel_hdcp *hdcp = &connector->hdcp;
> + bool force_hdcp14 = false;
> + int ret;
> +
> + if (len == 0)
> + return 0;
> +
> + drm_dbg(display->drm,
> + "Copied %zu bytes from user to force DSC\n", len);
Useless debug logging.
> +
> + ret = kstrtobool_from_user(ubuf, len, &force_hdcp14);
> + if (ret < 0)
> + return ret;
> +
> + drm_dbg(display->drm, "Got %s for force HDCP1.4\n",
> + (force_hdcp14) ? "true" : "false");
Also useless debug logging.
> + hdcp->force_hdcp14 = force_hdcp14;
> +
> + *offp += len;
> + return len;
> +}
> +
> +static int i915_force_hdcp14_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_hdcp *hdcp = &connector->hdcp;
> + struct drm_crtc *crtc;
> + int ret;
> +
> + if (!encoder)
> + return -ENODEV;
> +
> + ret = drm_modeset_lock_single_interruptible(&display->drm->mode_config.connection_mutex);
> + if (ret)
> + return ret;
> +
> + crtc = connector->base.state->crtc;
> + if (connector->base.status != connector_status_connected || !crtc) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + seq_printf(m, "Force_HDCP14: %s\n",
> + str_yes_no(hdcp->force_hdcp14));
So I'm not sure why we're printing "Force_HDCP14: " in there. Why isn't
just yes/no enough? The name of the debugfs attribute is literally
i915_force_hdcp14.
> +out:
> + drm_modeset_unlock(&display->drm->mode_config.connection_mutex);
Blank line before return please.
> + return ret;
> +}
> +
> +static int i915_force_hdcp14_open(struct inode *inode,
> + struct file *file)
> +{
> + return single_open(file, i915_force_hdcp14_show,
> + inode->i_private);
> +}
> +
> +static const struct file_operations i915_force_hdcp14_fops = {
> + .owner = THIS_MODULE,
> + .open = i915_force_hdcp14_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> + .write = i915_force_hdcp14_write
> +};
> +
> /**
> * intel_connector_debugfs_add - add i915 specific connector debugfs files
> * @connector: pointer to a registered intel_connector
> @@ -1411,6 +1485,8 @@ void intel_connector_debugfs_add(struct intel_connector *connector)
> connector_type == DRM_MODE_CONNECTOR_HDMIB) {
> debugfs_create_file("i915_hdcp_sink_capability", 0444, root,
> connector, &i915_hdcp_sink_capability_fops);
> + debugfs_create_file("i915_force_hdcp14", 0644, root,
> + connector, &i915_force_hdcp14_fops);
> }
>
> if (DISPLAY_VER(i915) >= 11 &&
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 6a82c6ade549..c78dd77ef74c 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -496,6 +496,8 @@ struct intel_hdcp {
> enum transcoder cpu_transcoder;
> /* Only used for DP MST stream encryption */
> enum transcoder stream_transcoder;
> + /* Used to force HDCP 1.4 bypassing HDCP 2.x */
> + bool force_hdcp14;
> };
>
> struct intel_connector {
> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> index 7cc0399b2a5d..c008e4f1ce05 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> @@ -2473,7 +2473,7 @@ static int _intel_hdcp_enable(struct intel_atomic_state *state,
> * Considering that HDCP2.2 is more secure than HDCP1.4, If the setup
> * is capable of HDCP2.2, it is preferred to use HDCP2.2.
> */
> - if (intel_hdcp2_get_capability(connector)) {
> + if (intel_hdcp2_get_capability(connector) && !hdcp->force_hdcp14) {
Why isn't this check inside intel_hdcp2_get_capability()? That's used in
more places, and now you've selected just one place that forces
1.4. Isn't that inconsistent?
Also, that might be a place to debug log about forcing hdcp2 support
off, if you really need debugfs.
> ret = _intel_hdcp2_enable(state, connector);
> if (!ret)
> check_link_interval =
--
Jani Nikula, Intel
