linux-kernel - Re: BUG caused by "Use new drm_fb

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Message-ID: <56B1C8CE.1090607@daenzer.net>
Date:	Wed, 3 Feb 2016 18:30:54 +0900
From:	Michel Dänzer <michel@...nzer.net>
To:	Peter Hurley <peter@...leysoftware.com>,
	Archit Taneja <architt@...eaurora.org>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Ben Skeggs <bskeggs@...hat.com>
Cc:	Linux kernel <linux-kernel@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: BUG caused by "Use new drm_fb_helper functions" series

On 03.02.2016 03:38, Peter Hurley wrote:
> On 02/01/2016 09:20 PM, Archit Taneja wrote:
>> Hi Peter,
>>
>> On 02/02/2016 02:07 AM, Peter Hurley wrote:
>>> Hi Archit,
>>>
>>> Just booting 4.4-rc5+, I got this splat [1]
>>> At first glance, this appears to be a simple fix.
>>
>> Thanks for sharing this.
>>
>>>
>>> However, I'm concerned that fbcon functions, which may be called with
>>> interrupts disabled, are now hooked up to fbdev functions which may assume
>>> interrupts are not disabled (as is the case with cfb_imageblit()).
>>
>> In the case when CONFIG_FB is enabled, drm_fb_helper_cfb_imageblit
>> helper simply wraps around cfg_imageblit, so I don't see how we'd have
>> any difference in behaviour.
> 
> 
> Sorry; terrible attribution on my part.
> This bug clearly has nothing to do with this series.
> 
> But a better look has me wondering how all these gpus are syncing
> the framebuffer for direct access via cfb_imageblit and friends. I only see
> nouveau and intel gma even trying.

Probably no other DRM driver uses hardware acceleration for fbcon.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer