Re: [PATCH 5/8] drm/i915: Optimize HDCP key load

Sean Paul
2018-02-02T14:18:13Z

On Fri, Feb 02, 2018 at 04:15:17PM +0530, Ramalingam C wrote:
> HDCP key need not be cleared on each hdcp disable. And HDCP key Load
> is skipped if key is already loaded.
>

I had previously encountered issues without clearing the key in my testing.
IIRC, without clearing the keys things acted differently. How much time are we
saving by optimizing this?

Sean

> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> ---
> drivers/gpu/drm/i915/intel_hdcp.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
> index fa2e7c727d00..5de9afd275b2 100644
> --- a/drivers/gpu/drm/i915/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/intel_hdcp.c
> @@ -51,6 +51,10 @@ static int intel_hdcp_load_keys(struct drm_i915_private *dev_priv)
> int ret;
> u32 val;
>
> + val = I915_READ(HDCP_KEY_STATUS);
> + if ((val & HDCP_KEY_LOAD_DONE) && (val & HDCP_KEY_LOAD_STATUS))
> + return 0;
> +
> /*
> * On HSW and BDW HW loads the HDCP1.4 Key when Display comes
> * out of reset. So if Key is not already loaded, its an error state.
> @@ -542,8 +546,6 @@ static int _intel_hdcp_disable(struct intel_connector *connector)
> return -ETIMEDOUT;
> }
>
> - intel_hdcp_clear_keys(dev_priv);
> -
> ret = connector->hdcp_shim->toggle_signalling(intel_dig_port, false);
> if (ret) {
> DRM_ERROR("Failed to disable HDCP signalling\n");
> --
> 2.7.4
>

--
Sean Paul, Software Engineer, Google / Chromium OS