Re: [PATCH v2 5/8] drm/i915/sysfs: Node for hdcp srm

[Daniel Vetter <daniel@ffwll.ch>]

On Sat, Mar 09, 2019 at 09:34:49AM +0530, Ramalingam C wrote:
> Binary Sysfs entry is created to pass the HDCP SRM table into
> kerel for the HDCP authentication purpose.
> 
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>

I think the srm stuff would sit very well in the drm core:
- sysfs file created in the overall drm directory, not in each driver
  directory
- validation code in core
- one function exported to drivers to get latest srm/version, so that
  every time they do a hdcp enable they can check whether they need to
  update the srm.

So this and previous patch as drm core changes, with a simple patch to tie
it into drm/i915.

I also still think that we don't really need userspace for this, since the
use-case is that you echo $latest_srm_file > $sysfs_srm_file once at boot.
Really doesn't need userspace imo.
-Daniel
> ---
>  drivers/gpu/drm/i915/i915_sysfs.c | 32 +++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index 41313005af42..4621e944a24e 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -576,6 +576,36 @@ static void i915_setup_error_capture(struct device *kdev) {}
>  static void i915_teardown_error_capture(struct device *kdev) {}
>  #endif
>  
> +static ssize_t
> +i915_srm_write(struct file *filp, struct kobject *kobj,
> +	       struct bin_attribute *attr, char *buf,
> +	       loff_t offset, size_t count)
> +{
> +	struct device *kdev = kobj_to_dev(kobj);
> +	struct drm_i915_private *dev_priv = kdev_minor_to_i915(kdev);
> +
> +	return intel_hdcp_srm_update(dev_priv, buf, count);
> +}
> +
> +static const struct bin_attribute srm_attrs = {
> +	.attr = {.name = "hdcp_srm", .mode = S_IWUSR},
> +	.read = NULL,
> +	.write = i915_srm_write,
> +	.mmap = NULL,
> +	.private = (void *)0
> +};
> +
> +static void i915_setup_hdcp_srm(struct device *kdev)
> +{
> +	if (sysfs_create_bin_file(&kdev->kobj, &srm_attrs))
> +		DRM_ERROR("error_state sysfs setup failed\n");
> +}
> +
> +static void i915_teardown_hdcp_srm(struct device *kdev)
> +{
> +	sysfs_remove_bin_file(&kdev->kobj, &srm_attrs);
> +}
> +
>  void i915_setup_sysfs(struct drm_i915_private *dev_priv)
>  {
>  	struct device *kdev = dev_priv->drm.primary->kdev;
> @@ -623,12 +653,14 @@ void i915_setup_sysfs(struct drm_i915_private *dev_priv)
>  		DRM_ERROR("RPS sysfs setup failed\n");
>  
>  	i915_setup_error_capture(kdev);
> +	i915_setup_hdcp_srm(kdev);
>  }
>  
>  void i915_teardown_sysfs(struct drm_i915_private *dev_priv)
>  {
>  	struct device *kdev = dev_priv->drm.primary->kdev;
>  
> +	i915_teardown_hdcp_srm(kdev);
>  	i915_teardown_error_capture(kdev);
>  
>  	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> -- 
> 2.19.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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