[Intel-gfx] [PATCH 1/2] drm/i915: Remove the MI_FLUSH_ENABLE setting.

Ben Widawsky ben at bwidawsk.net
Sat Jan 21 05:47:24 CET 2012

On 01/20/2012 04:40 PM, Eric Anholt wrote:
> On Fri, 20 Jan 2012 14:57:44 -0800, Ben Widawsky <ben at bwidawsk.net> wrote:
>> On 01/20/2012 11:16 AM, Eric Anholt wrote:
>>> On Thu, 19 Jan 2012 10:59:57 -0800, Ben Widawsky <ben at bwidawsk.net> wrote:
>>>> On 01/19/2012 10:54 AM, Keith Packard wrote:
>>>>> On Thu, 19 Jan 2012 10:50:05 -0800, Eric Anholt <eric at anholt.net> wrote:
>>>>>> -		if (IS_GEN6(dev) || IS_GEN7(dev))
>>>>>> -			mode |= MI_FLUSH_ENABLE << 16 | MI_FLUSH_ENABLE;
>>>>> This seems better than setting random bits that don't do anything but
>>>>> annoy the simulator.
>>>> The simulator complains unless both bits are set iirc. I can double
>>>> check, but it's been a while since I've run without my patch.
>>> Can you please cite the message you're getting?  I've read a lot of the
>>> simulator at this point, particularly pieces relating to flushing, and I
>>> can't find what you're talking about.
>> It is not email friendly paste.
>> Gen7GT/Render/src/CsMiCommonCatcher.cpp +293
>> It links to a power point which shows the workaround is to set both
>> bits. The powerpoint is kind enough to crash libreoffice for me.
> That block is checking exactly one bit, bit 12, in my tree.

Hmm, it appears I had some PEBPAC (phone and chair). I sent two earlier
emails, and the semi-useful one never seemed to make it. Well this gives
me a chance to elaborate anyway.

You have to read the powerpoint. In there it says to set both bits. It
looks like I was incorrect about the simulator itself caring, that
indeed only checks for bit 12. I think it's all moot anyway, as it
appears bit 12 (with or without bit 11) doesn't play nice with IVB.

To sum up there are three options
Bit 11, wrong in docs, wrong in simulator, wrong in ppt; doesn't hang
Bit 12, right in docs, right in simulator, wrong in ppt; hangs (I think)
Bit 11|12, sorta wrong/right in docs an simulator, right in ppt; hangs

And I honestly don't care which we go with if the simulator logs don't
tell me everytime that bit 12 wasn't set.


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