linux-kernel - Re: [PATCH 2/2] drm/msm/hdmi: add hdmi hdcp support (V2)

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Date:	Wed, 11 Feb 2015 18:59:16 -0000
From:	jilaiw@...eaurora.org
To:	"Bjorn Andersson" <bjorn@...o.se>
Cc:	"Jilai Wang" <jilaiw@...eaurora.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-arm-msm" <linux-arm-msm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Rob Clark" <robdclark@...il.com>
Subject: Re: [PATCH 2/2] drm/msm/hdmi: add hdmi hdcp support (V2)

There is one issue to use i2c_smbus_XX functions:
i2c_smbus_read_i2c_block_data has limitation with the maximum count 
I2C_SMBUS_BLOCK_MAX.
But in function hdmi_hdcp_recv_ksv_fifo, since the downstream ksv_fifo
size will exceed this limitation and must be read in a single transaction,
we can't use this function then.

> On Fri, Jan 30, 2015 at 2:39 PM, Bjorn Andersson <bjorn@...o.se> wrote:
>> On Fri, Jan 30, 2015 at 1:51 PM, Bjorn Andersson <bjorn@...o.se> wrote:
>>> On Tue, Jan 13, 2015 at 12:43 PM, Jilai Wang <jilaiw@...eaurora.org>
>>> wrote:
>>>> Add HDMI HDCP support including HDCP PartI/II/III authentication.
>>>> V1: Initial Change
>>>> V2: Address Bjorn&Rob's comments
>>>>     Refactor the authentication process to use single work instead
>>>>     of multiple work for different authentication stages.
>>>>
>>> Looks cleaner and the SCM parts look good now.
>>>
>>> But the ddc communication still makes me wonder, see below.
>>>
>>
>> Rob made me aware about the fact that the hdmi driver is both
>> implementing a driver for the i2c controller and now for the hdcp
>> client and hence doesn't have an i2c_client handle.
>>
>> So unless this is redesigned to be split in a separate i2c client
>> driver we probably have to have the ddc functions like this.
>>
>> I'm fine with this as is for now.
>>
>
> After digging some more in the i2c stack I found others using
> i2c_new_dummy() to create a "dummy" i2c client from and adaptor and an
> address.
> By introducing that we could make hdmi->i2c an actual i2c_client and
> use the client api in here.
>
> Regards,
> Bjorn
>


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