On 23 June 2014 20:37, Wang, Quanxian <quanxian.w...@intel.com> wrote:
>
>
>> -----Original Message-----
>> From: Jani Nikula [mailto:jani.nik...@linux.intel.com]
>> Sent: Tuesday, June 17, 2014 11:38 PM
>> To: Wang, Quanxian
>> Cc: intel-gfx@lists.freedesktop.org; Daniel Vetter
>> Subject: RE: [Intel-gfx] [PATCH] drm/i915/vlv: DP_SINK_COUNT is not reliable
>> for valleyview platform.
>>
>> On Tue, 17 Jun 2014, "Wang, Quanxian" <quanxian.w...@intel.com> wrote:
>> > File dmesg_normal_20140617.log will contain dmesg log when boot the
>> > machine and start weston. (Previous is overwrite, but it is enough for
>> graphics boot message) File dmesg_error_20140617.log contains dmesg log
>> after Weston exit when it found no connector available.
>> >
>> > I disable log for  hotplug event from valleyview_irq_handler. There are so
>> many. Maybe you can find some private debug log. Don't need to care that.
>>
>> Per DP spec we need to read the SINK_COUNT. Perhaps your problem is the
>> hotplug irqs?
> [Wang, Quanxian] Hi, Jani
> The log event is about the transaction event instead of hotplug event. It is 
> general since they will use I2c to read byte one by one. It will generate 
> many transaction.
>
> But the root cause is really about hotplug(intel_hpd_irq_handler). When we 
> switch to console, there will be a hotplug event happens after a while. After 
> that, the system will continually get the hotplug event to switch sink device 
> on and off periodly.  With DisplayPort 1.2 spec, '' This bit is used for 
> either monitor hotplug/unplug or for notification of a sink event.", I am not 
> sure if it is notification of  a sink event or real hotplug event. We have no 
> code to identify the difference between hotplug/unplug  and notification of a 
> sink event. I check display port spec and also not found how to identify them 
> differently.
>
There are patches on the list to distinguish between short and long
hpd irqs, they are need of review.

Dave.
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