From mboxrd@z Thu Jan 1 00:00:00 1970 From: "C, Ramalingam" Subject: Re: [PATCH v9 10/39] drm/i915: Implement HDCP2.2 receiver authentication Date: Wed, 19 Dec 2018 21:18:20 +0530 Message-ID: <7ed9278c-2e4b-3d3e-45ef-65c13c18d68f@intel.com> References: <1544673701-6353-1-git-send-email-ramalingam.c@intel.com> <1544673701-6353-11-git-send-email-ramalingam.c@intel.com> <20181219143512.GF21184@phenom.ffwll.local> <5d0ac1d4-d85d-2238-978a-417362a830bd@intel.com> <20181219153519.GN21184@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2127140159==" Return-path: In-Reply-To: <20181219153519.GN21184@phenom.ffwll.local> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Daniel Vetter Cc: daniel.vetter@ffwll.ch, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, seanpaul@chromium.org, tomas.winkler@intel.com List-Id: dri-devel@lists.freedesktop.org This is a multi-part message in MIME format. --===============2127140159== Content-Type: multipart/alternative; boundary="------------9956B4D78E76F63417C73F1C" Content-Language: en-US This is a multi-part message in MIME format. --------------9956B4D78E76F63417C73F1C Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit On 12/19/2018 9:05 PM, Daniel Vetter wrote: > On Wed, Dec 19, 2018 at 08:35:48PM +0530, C, Ramalingam wrote: >> On 12/19/2018 8:05 PM, Daniel Vetter wrote: >>> On Thu, Dec 13, 2018 at 09:31:12AM +0530, Ramalingam C wrote: >>>> + if (!hdcp->is_repeater && shim->config_stream_type) { >>>> + /* >>>> + * Errata for DP: As Stream type is used for encryption, >>>> + * Receiver should be communicated with stream type for the >>>> + * decryption of the content. >>>> + * Repeater will be communicated with stream type as a >>>> + * part of it's auth later in time. >>>> + */ >>> I'm not following what you want to say with this comment, and haven't >>> found anything in the hdcp2 dp spec about this either. >> this is there in the errata of DP HDCP2.2 spec. >> hdcp2.2 encryption algo involves the stream type as a parameter. >> And as part of hdcp auth mentioned in base spec DP repeaters receive that details to decrypt the content. >> But DP receivers dont get it. So errata adds the missing piece for decryption. > Ok I found it, but the fake HDCP_2_2_ERRATA_DP_STREAM_TYPE define is kinda > annoying. It doesn't exist in the spec, but we put it into the drm_hdcp.h > header. Since you have a special ->config_stream_type hook for this > anyway, and it's only needed for DP, please move that into the shim > implementation. > > And then a follow-up patch to remove the fake #define from drm_hdcp.h. This is defined to make the hdcp_shim interface to look common between DP and HDMI. We can move this errata msg definition and its msg_id into intel_drv.h just for the intel's consumption. -Ram > -Daniel --------------9956B4D78E76F63417C73F1C Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit


On 12/19/2018 9:05 PM, Daniel Vetter wrote:
On Wed, Dec 19, 2018 at 08:35:48PM +0530, C, Ramalingam wrote:

On 12/19/2018 8:05 PM, Daniel Vetter wrote:

On Thu, Dec 13, 2018 at 09:31:12AM +0530, Ramalingam C wrote:

+	if (!hdcp->is_repeater && shim->config_stream_type) {
+		/*
+		 * Errata for DP: As Stream type is used for encryption,
+		 * Receiver should be communicated with stream type for the
+		 * decryption of the content.
+		 * Repeater will be communicated with stream type as a
+		 * part of it's auth later in time.
+		 */

I'm not following what you want to say with this comment, and haven't
found anything in the hdcp2 dp spec about this either.

this is there in the errata of DP HDCP2.2 spec.
hdcp2.2 encryption algo involves the stream type as a parameter.
And as part of hdcp auth mentioned in base spec DP repeaters receive that details to decrypt the content.
But DP receivers dont get it. So errata adds the missing piece for decryption.

Ok I found it, but the fake HDCP_2_2_ERRATA_DP_STREAM_TYPE define is kinda
annoying. It doesn't exist in the spec, but we put it into the drm_hdcp.h
header. Since you have a special ->config_stream_type hook for this
anyway, and it's only needed for DP, please move that into the shim
implementation.

And then a follow-up patch to remove the fake #define from drm_hdcp.h.
This is defined to make the hdcp_shim interface to look common between DP and HDMI.
We can move this errata msg definition and its msg_id into intel_drv.h just for the intel's consumption.

-Ram

-Daniel
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