[PATCH v8 03/35] linux/mei: Header for mei_hdcp driver interface

Winkler, Tomas tomas.winkler at intel.com
Sat Dec 8 20:15:52 UTC 2018


> On Fri, Dec 07, 2018 at 07:23:06PM +0530, C, Ramalingam wrote:
> > Hi,
> >
> > In one of the offline discussion Tomas has shared his review comments on v8.
> 
> Let's please have all review here on the mailing list for better coordination.
> Playing a game of telephone isn't efficient.
It's not different from IRC or meeting on a conference, after all we end up with code we can comment on. 
> 
> > So I am sharing the abstract of his suggestions here for the discussion and for
> the agreement of interface in the community.
> > Tomas please correct/add if I am missing any points.
> >
> > 1. Remove the include/linux/mei_hdcp.h to make the i915-mei interface
> >    more generic.
> >     1. Move the definition of the struct mei_hdcp_data to i915 and
> >        mei_hdcp.c and pass the void* in the ops' functions.
> 
> I don't get this. Using void * instead of the actual type we're passing isn't more
> generic, it's just less safe. If we later on need to extend the api contract
> between mei_hdcp and i915 we can always do that. Like we already do with the
> i915/snd-hda-intel component contract in i915_component.h and
> drm_audio_component.h.

No I haven't suggesting using void *, what I've suggest is to use HDCP construct instead of mei specific types.

> Aside: Header names for the audio interface are maybe not the best, this isn't
> primarily a component thing. So maybe call it i915_mei_hdcp_interface.h and
> stuff all the structures/function pointers that define the interface between the
> two drivers in there. Or some other suitable name you like better.
> 
> >     2. Move the conversion of enum port value to mei_ddi_port value
> >        into mei_hdcp.c. Let I915 pass the enum port value as such.
> 
> logical port 2 physical register index mapping tends to shift around and is
> always highly machine specific. As long as we do it consistently somewhere we
> should be good. Seems fine to me.
> 
> >     3. Modified local definition of the struct mei_hdcp_data will looks
> >        like
> 
> No local defintions of structures please. Otherwise I'm ok with whatever gets
> the job done.
> 
> >     4.
> >
> >        +/* hdcp data per port */
> >        +struct hdcp_port_data {
> >        + short int port;
> >        + u8 port_type;
> >        + u8 protocol;
> >        + u16 k;
> >        + u32 seq_num_m;
> >        + struct hdcp2_streamid_type *streams;
> >          };
> >
> > 2. Add K-Doc compliant commenting in the mei_hdcp.c
> 
> If you do that, please include the relevant comments into the drm/i915
> docbook, like we do already with the audio stuff.
> 
> > I have implemented these changes and posted for intel-gfx-trybot. Just
> > incase anyone wants to refer the code please look at
> https://patchwork.freedesktop.org/series/53655/ .
> > Not shared on #intel-gfx as further review discussions are on-going on intel-
> gfx.
> 
> As discussed, no void * in the interface, and we definitely need a shared header
> for ops/data structures. We want the compiler to help us catch when one side
> of this i915/mei_hdcp api contract changes as much as possible.
> All the other changes seem reasonable.

> Thanks, Daniel
I agree with no void *, that was not my intention. 
It will be better to comment on v9 series. 

 
> >
> 
> > --Ram
> >
> > On 11/27/2018 4:13 PM, Ramalingam C wrote:
> > > Data structures and Enum for the I915-MEI_HDCP interface are defined
> > > at <linux/mei_hdcp.h>
> > >
> > > v2:
> > >    Rebased.
> > > v3:
> > >    mei_cl_device is removed from mei_hdcp_data [Tomas]
> > > v4:
> > >    Comment style and typo fixed [Uma]
> > > v5:
> > >    Rebased.
> > > v6:
> > >    No changes.
> > > v7:
> > >    Remove redundant text from the License header
> > >    Change uintXX_t type to uXX_t types
> > >    Remove unneeded include to mei_cl_bus.h
> > >    Coding style fixed [Uma]
> > > V8:
> > >    Tab cleanup
> > >    Fix kdoc and namespaces
> > >    Update MAINTAINERS
> > >
> > > Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
> > > Signed-off-by: Tomas Winkler <tomas.winkler at intel.com>
> > > Reviewed-by: Uma Shankar <uma.shankar at intel.com>
> > > ---
> > >   MAINTAINERS              |  1 +
> > >   include/linux/mei_hdcp.h | 91
> ++++++++++++++++++++++++++++++++++++++++++++++++
> > >   2 files changed, 92 insertions(+)
> > >   create mode 100644 include/linux/mei_hdcp.h
> > >
> > > diff --git a/MAINTAINERS b/MAINTAINERS index
> > > 1026150ae90f..2fd6555bf040 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -7540,6 +7540,7 @@ L:	linux-kernel at vger.kernel.org
> > >   S:	Supported
> > >   F:	include/uapi/linux/mei.h
> > >   F:	include/linux/mei_cl_bus.h
> > > +F:	include/linux/mei_hdcp.h
> > >   F:	drivers/misc/mei/*
> > >   F:	drivers/watchdog/mei_wdt.c
> > >   F:	Documentation/misc-devices/mei/*
> > > diff --git a/include/linux/mei_hdcp.h b/include/linux/mei_hdcp.h new
> > > file mode 100644 index 000000000000..716123003dd1
> > > --- /dev/null
> > > +++ b/include/linux/mei_hdcp.h
> > > @@ -0,0 +1,91 @@
> > > +/* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
> > > +/*
> > > + * Copyright (c) 2017-2018 Intel Corporation
> > > + *
> > > + * Authors:
> > > + * Ramalingam C <ramalingam.c at intel.com>  */
> > > +
> > > +#ifndef _LINUX_MEI_HDCP_H
> > > +#define _LINUX_MEI_HDCP_H
> > > +
> > > +/**
> > > + * enum mei_hdcp_ddi - The physical digital display interface (DDI)
> > > + *     available on the platform
> > > + * @MEI_DDI_INVALID_PORT: Not a valid port
> > > + * @MEI_DDI_RANGE_BEGIN: Beginning of the valid DDI port range
> > > + * @MEI_DDI_B: Port DDI B
> > > + * @MEI_DDI_C: Port DDI C
> > > + * @MEI_DDI_D: Port DDI D
> > > + * @MEI_DDI_E: Port DDI E
> > > + * @MEI_DDI_F: Port DDI F
> > > + * @MEI_DDI_A: Port DDI A
> > > + * @MEI_DDI_RANGE_END: End of the valid DDI port range  */ enum
> > > +mei_hdcp_ddi {
> > > +	MEI_DDI_INVALID_PORT = 0x00,
> > > +
> > > +	MEI_DDI_RANGE_BEGIN = 0x01,
> > > +	MEI_DDI_B           = 0x01,
> > > +	MEI_DDI_C           = 0x02,
> > > +	MEI_DDI_D           = 0x03,
> > > +	MEI_DDI_E           = 0x04,
> > > +	MEI_DDI_F           = 0x05,
> > > +	MEI_DDI_A           = 0x07,
> > > +	MEI_DDI_RANGE_END   = MEI_DDI_A,
> > > +};
> > > +
> > > +/**
> > > + * enum mei_hdcp_port_type - The types of HDCP 2.2 ports supported
> > > + *
> > > + * @MEI_HDCP_PORT_TYPE_INVALID: Invalid port
> > > + * @MEI_HDCP_PORT_TYPE_INTEGRATED: ports that are integrated into
> > > +Intel HW
> > > + * @MEI_HDCP_PORT_TYPE_LSPCON: discrete wired Tx port with LSPCON
> > > +(HDMI 2.0)
> > > + * @MEI_HDCP_PORT_TYPE_CPDP: discrete wired Tx port using the CPDP
> > > +(DP 1.3)  */ enum mei_hdcp_port_type {
> > > +	MEI_HDCP_PORT_TYPE_INVALID    = 0x00,
> > > +	MEI_HDCP_PORT_TYPE_INTEGRATED = 0x01,
> > > +	MEI_HDCP_PORT_TYPE_LSPCON     = 0x02,
> > > +	MEI_HDCP_PORT_TYPE_CPDP       = 0x03,
> > > +};
> > > +
> > > +/*
> > > + * enum mei_hdcp_wired_protocol - Supported integrated wired HDCP
> protocol.
> > > + * @HDCP_PROTOCOL_INVALID: invalid type
> > > + * @HDCP_PROTOCOL_HDMI: HDMI
> > > + * @HDCP_PROTOCOL_DP: DP
> > > + *
> > > + * Based on this value, Minor difference needed between wired
> > > +specifications
> > > + * are handled.
> > > + */
> > > +enum mei_hdcp_wired_protocol {
> > > +	MEI_HDCP_PROTOCOL_INVALID,
> > > +	MEI_HDCP_PROTOCOL_HDMI,
> > > +	MEI_HDCP_PROTOCOL_DP
> > > +};
> > > +
> > > +/**
> > > + * struct mei_hdcp_data - Input data to the mei_hdcp APIs
> > > + * @port: The physical port (ddi).
> > > + * @port_type: The port type.
> > > + * @protocol: The Protocol on the port.
> > > + * @k: Number of streams transmitted on the port.
> > > + *     In case of HDMI & DP SST, a single stream will be
> > > + *     transmitted on the port.
> > > + * @seq_num_m: A sequence number of RepeaterAuth_Stream_Manage
> msg propagated.
> > > + *     Initialized to 0 on AKE_INIT. Incremented after every successful
> > > + *     transmission of RepeaterAuth_Stream_Manage message. When it
> rolls
> > > + *     over re-Auth has to be triggered.
> > > + * @streams: array[k] of streamid
> > > + */
> > > +struct mei_hdcp_data {
> > > +	enum mei_hdcp_ddi port;
> > > +	enum mei_hdcp_port_type port_type;
> > > +	enum mei_hdcp_wired_protocol protocol;
> > > +	u16 k;
> > > +	u32 seq_num_m;
> > > +	struct hdcp2_streamid_type *streams; };
> > > +
> > > +#endif /* !_LINUX_MEI_HDCP_H */
> 
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch


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