Re: [PATCH 01/43] drm: hdcp2.2 authentication msg definitions

From: Jani Nikula <jani.nikula@linux.intel.com>
To: "Winkler, Tomas" <tomas.winkler@intel.com>,
	"C, Ramalingam" <ramalingam.c@intel.com>,
	"seanpaul@chromium.org" <seanpaul@chromium.org>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"Vivi, Rodrigo" <rodrigo.vivi@intel.com>,
	"daniel.vetter@ffwll.ch" <daniel.vetter@ffwll.ch>
Subject: Re: [PATCH 01/43] drm: hdcp2.2 authentication msg definitions
Date: Wed, 14 Feb 2018 21:40:54 +0200	[thread overview]
Message-ID: <873723jr5l.fsf@intel.com> (raw)
In-Reply-To: <5B8DA87D05A7694D9FA63FD143655C1B9422098C@hasmsx108.ger.corp.intel.com>

On Wed, 14 Feb 2018, "Winkler, Tomas" <tomas.winkler@intel.com> wrote:
>> 
>> This patch defines the hdcp2.2 protocol messages for the
>> HDCP2.2 authentication.
>> 
>> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
>> ---
>>  include/drm/drm_hdcp.h | 226
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 226 insertions(+)
>> 
>> diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h index
>> 562fa7df2637..9661c700cebb 100644
>> --- a/include/drm/drm_hdcp.h
>> +++ b/include/drm/drm_hdcp.h
>> @@ -38,4 +38,230 @@
>>  #define DRM_HDCP_DDC_BSTATUS			0x41
>>  #define DRM_HDCP_DDC_KSV_FIFO			0x43
>> 
>> +#define DRM_HDCP_1_4_SRM_ID			0x8
>> +#define DRM_HDCP_1_4_VRL_LENGTH_SIZE		3
>> +#define DRM_HDCP_1_4_DCP_SIG_SIZE		40
>> +
>> +struct cp_srm_header {
>> +	struct {
>> +		uint8_t reserved_hi:4;
>> +		uint8_t srm_id:4;
>> +		uint8_t reserved_lo;
>> +	} spec_indicator;
> Do you really want to work with bit fields?  I mean in all the all structures.

We *can't* use bitfields in drm core for (un)marshalling. They depend on
endianness. (Thanks to folks on #dri-devel for confirming.) We use them
at places in i915 where we can be pretty sure about running on
little-endian machines, but that doesn't hold here.

Packed structs are fine otherwise though, just not bitfields.

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Technology Center
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