linux-kernel - Re: [TSN RFC v2 5/9] Add TSN header for the driver

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Date:   Sat, 17 Dec 2016 09:53:57 +0100
From:   Henrik Austad <henrik@...tad.us>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     linux-kernel@...r.kernel.org, Henrik Austad <haustad@...co.com>,
        linux-media@...r.kernel.org, alsa-devel@...r.kernel.org,
        netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: Re: [TSN RFC v2 5/9] Add TSN header for the driver

On Fri, Dec 16, 2016 at 11:09:38PM +0100, Richard Cochran wrote:
> On Fri, Dec 16, 2016 at 06:59:09PM +0100, henrik@...tad.us wrote:
> > +/*
> > + * List of current subtype fields in the common header of AVTPDU
> > + *
> > + * Note: AVTPDU is a remnant of the standards from when it was AVB.
> > + *
> > + * The list has been updated with the recent values from IEEE 1722, draft 16.
> > + */
> > +enum avtp_subtype {
> > +	TSN_61883_IIDC = 0,	/* IEC 61883/IIDC Format */
> > +	TSN_MMA_STREAM,		/* MMA Streams */
> > +	TSN_AAF,		/* AVTP Audio Format */
> > +	TSN_CVF,		/* Compressed Video Format */
> > +	TSN_CRF,		/* Clock Reference Format */
> > +	TSN_TSCF,		/* Time-Synchronous Control Format */
> > +	TSN_SVF,		/* SDI Video Format */
> > +	TSN_RVF,		/* Raw Video Format */
> > +	/* 0x08 - 0x6D reserved */
> > +	TSN_AEF_CONTINOUS = 0x6e, /* AES Encrypted Format Continous */
> > +	TSN_VSF_STREAM,		/* Vendor Specific Format Stream */
> > +	/* 0x70 - 0x7e reserved */
> > +	TSN_EF_STREAM = 0x7f,	/* Experimental Format Stream */
> > +	/* 0x80 - 0x81 reserved */
> > +	TSN_NTSCF = 0x82,	/* Non Time-Synchronous Control Format */
> > +	/* 0x83 - 0xed reserved */
> > +	TSN_ESCF = 0xec,	/* ECC Signed Control Format */
> > +	TSN_EECF,		/* ECC Encrypted Control Format */
> > +	TSN_AEF_DISCRETE,	/* AES Encrypted Format Discrete */
> > +	/* 0xef - 0xf9 reserved */
> > +	TSN_ADP = 0xfa,		/* AVDECC Discovery Protocol */
> > +	TSN_AECP,		/* AVDECC Enumeration and Control Protocol */
> > +	TSN_ACMP,		/* AVDECC Connection Management Protocol */
> > +	/* 0xfd reserved */
> > +	TSN_MAAP = 0xfe,	/* MAAP Protocol */
> > +	TSN_EF_CONTROL,		/* Experimental Format Control */
> > +};
> 
> The kernel shouldn't be in the business of assembling media packets.

No, but assembling the packets and shipping frames to a destination is not 
neccessarily the same thing.

A nice workflow would be to signal to the shim that "I'm sending a 
compressed video format" and then the shim/tsn_core will ship out the 
frames over the network - and then you need to set TSN_CVF as subtype in 
each header.

That does not that mean you should do H.264 encode/decode *in* the kernel

Perhaps this is better placed in include/uapi/tsn.h so that userspace and 
kernel share the same header?

-- 
Henrik Austad

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