On Fri, 2018-10-05 at 16:23 -0700, Manasi Navare wrote:
> DSC can be supported per DP connector. This patch adds a per connector
> debugfs node to expose DSC support capability by the kernel.
> The same node can be used from userspace to force DSC enable.
>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
> Cc: Lyude Paul <lyude@xxxxxxxxxx>
> Signed-off-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 83 ++++++++++++++++++++++++++++-
> drivers/gpu/drm/i915/intel_dp.c | 1 +
> drivers/gpu/drm/i915/intel_drv.h | 3 ++
> 3 files changed, 86 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> b/drivers/gpu/drm/i915/i915_debugfs.c
> index f42e93b71e67..aeb20f06c79c 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4950,6 +4950,84 @@ static int i915_panel_show(struct seq_file *m, void
> *data)
> }
> DEFINE_SHOW_ATTRIBUTE(i915_panel);
>
> +static int i915_dsc_support_show(struct seq_file *m, void *data)
> +{
> + struct drm_connector *connector = m->private;
> + struct intel_encoder *encoder = intel_attached_encoder(connector);
> + struct intel_dp *intel_dp =
> + enc_to_intel_dp(&encoder->base);
> + struct intel_crtc *crtc;
> + struct intel_crtc_state *crtc_state;
> +
Since we're reading from the connector status here, we should probably create
a drm_modeset_acquire_ctx and grab the connector status lock, followed by the
respective CRTC lock.
It's probably also a good idea to use an interruptible acquire ctx for this so
the user can ^C out if grabbing the lock takes too long, presumably due to
something in the kernel having hung.
> + if (connector->status != connector_status_connected)
> + return -ENODEV;
> +
> + crtc = to_intel_crtc(encoder->base.crtc);
> + crtc_state = to_intel_crtc_state(crtc->base.state);
> + drm_modeset_lock(&crtc->base.mutex, NULL);
> + seq_printf(m, "Enabled: %s\n",
> + yesno(crtc_state->dsc_params.compression_enable));
> + seq_printf(m, "Supported: %s\n",
> + yesno(drm_dp_sink_supports_dsc(intel_dp->dsc_dpcd)));
> + drm_modeset_unlock(&crtc->base.mutex);
> +
> + return 0;
> +}
> +
> +static ssize_t i915_dsc_support_write(struct file *file,
> + const char __user *ubuf,
> + size_t len, loff_t *offp)
> +{
> + char *input_buffer;
> + int status = 0;
> + bool val = false;
> + struct drm_connector *connector =
> + ((struct seq_file *)file->private_data)->private;
> + struct intel_encoder *encoder = intel_attached_encoder(connector);
> + struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
I think you forgot to lock connection_mutex here!
> +
> + if (len == 0)
> + return 0;
> +
> + input_buffer = memdup_user_nul(ubuf, len);
> + if (IS_ERR(input_buffer))
> + return PTR_ERR(input_buffer);
> +
> + DRM_DEBUG_DRIVER("Copied %d bytes from user to force DSC\n",
> + (unsigned int)len);
> +
> + status = kstrtobool(input_buffer, &val);
You can get rid of most of this and just replace it with
kstrtobool_from_user(), which should do all of those checks for you.
> + DRM_DEBUG_DRIVER("Got %s for DSC Enable\n",
> + (val) ? "true" : "false");
> + /* To prevent erroneous enabling/disabling of DSC
> + * testing code, only accept an actual value of 1 or 0
> + */
> + intel_dp->force_dsc_en = val;
> +
> + kfree(input_buffer);
> + if (status < 0)
> + return status;
> +
> + *offp += len;
> + return len;
> +}
> +
> +static int i915_dsc_support_open(struct inode *inode,
> + struct file *file)
> +{
> + return single_open(file, i915_dsc_support_show,
> + inode->i_private);
> +}
> +
> +static const struct file_operations i915_dsc_support_fops = {
> + .owner = THIS_MODULE,
> + .open = i915_dsc_support_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> + .write = i915_dsc_support_write
> +};
> +
> /**
> * i915_debugfs_connector_add - add i915 specific connector debugfs files
> * @connector: pointer to a registered drm_connector
> @@ -4968,9 +5046,12 @@ int i915_debugfs_connector_add(struct drm_connector
> *connector)
> return -ENODEV;
>
> if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> - connector->connector_type == DRM_MODE_CONNECTOR_eDP)
> + connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> debugfs_create_file("i915_dpcd", S_IRUGO, root,
> connector, &i915_dpcd_fops);
> + debugfs_create_file("i915_dsc_support", S_IRUGO, root,
> + connector, &i915_dsc_support_fops);
> + }
>
> if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> debugfs_create_file("i915_panel_timings", S_IRUGO, root,
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c
> index 9a4012f3f1da..52dca5901aa1 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2252,6 +2252,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
> return false;
>
> + DRM_DEBUG_KMS("Force DSC en = %d\n", intel_dp->force_dsc_en);
> if (!intel_dp_compute_link_config(encoder, pipe_config))
> return false;
>
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index 3996df385d33..b713b2a2d1ac 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1163,6 +1163,9 @@ struct intel_dp {
>
> /* Displayport compliance testing */
> struct intel_dp_compliance compliance;
> +
> + /* Display stream compression testing */
I'd mention here that this is for debugfs as well, "Display stream compression
testing" is a bit vague
> + bool force_dsc_en;
> };
>
> struct intel_lspcon {
--
Cheers,
Lyude Paul
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