From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754429AbbBDDsg (ORCPT ); Tue, 3 Feb 2015 22:48:36 -0500 Received: from mail-vc0-f175.google.com ([209.85.220.175]:63456 "EHLO mail-vc0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752576AbbBDDsd convert rfc822-to-8bit (ORCPT ); Tue, 3 Feb 2015 22:48:33 -0500 MIME-Version: 1.0 In-Reply-To: <54D19426.4080105@rock-chips.com> References: <1422693698-21944-1-git-send-email-mark.yao@rock-chips.com> <54CEE131.1020600@rock-chips.com> <20150202075337.GN14009@phenom.ffwll.local> <54D19426.4080105@rock-chips.com> From: Daniel Kurtz Date: Wed, 4 Feb 2015 11:48:10 +0800 X-Google-Sender-Auth: AysqcnZLxnUp3BwToCMBTDtxmxc Message-ID: Subject: Re: [PATCH] drm/rockchip: vop: power off until vop standby take effect To: Mark yao Cc: "linux-kernel@vger.kernel.org" , dri-devel , Philipp Zabel , David Airlie , Rob Clark , "open list:ARM/Rockchip SoC..." Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Feb 4, 2015 11:38 AM, "Mark yao" wrote: > > On 2015年02月02日 15:53, Daniel Vetter wrote: >> >> On Mon, Feb 02, 2015 at 10:30:09AM +0800, Mark yao wrote: >>> >>> On 2015年02月02日 10:07, Daniel Kurtz wrote: >>>> >>>> Hi Mark, Heiko, >>>> >>>> On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao wrote: >>>>> >>>>> Vop standby will take effect end of current frame, >>>>> if dsp_hold_valid_irq happen, it means vop standby complete. >>>>> >>>>> we must wait standby complete when we want to disable aclk, >>>>> if not, memory bus maybe dead. >>>>> >>>>> Signed-off-by: Mark Yao >>>>> --- >>>>> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 76 ++++++++++++++++++++++----- >>>>> 1 file changed, 63 insertions(+), 13 deletions(-) >>>>> >>>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c >>>>> index fb25836..47ea61f 100644 >>>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c >>>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c >>>>> @@ -89,6 +89,7 @@ struct vop { >>>>> /* mutex vsync_ work */ >>>>> struct mutex vsync_mutex; >>>>> bool vsync_work_pending; >>>>> + struct completion dsp_hold_completion; >>>>> >>>>> const struct vop_data *data; >>>>> >>>>> @@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format) >>>>> } >>>>> } >>>>> >>>>> +static void vop_dsp_hold_valid_irq_enable(struct vop *vop) >>>>> +{ >>>>> + unsigned long flags; >>>>> + >>>>> + BUG_ON(!vop->is_enabled); >>>> >>>> Re: Heiko "use a WARN_ON": >>>> >>>> If the VOP clock is off, then the system will just hang when trying to >>>> write the VOP register so in this case, BUG_ON gives a more reliable >>>> crash dump than the hang. >>> >>> In this way, you are right, if vop clocks is disabled, write vop register >>> will hang system, and the WARN_ON >> >> if (WARN_ON(cond)) >> return; >> >> is what we commonly use in i915. Because it's really not any good to use >> BUG_ON in drm drivers, at least if you expect anyone to use fbcon on top >> of it (i.e. anything even remotely resembling a normal distro): Then the >> intial modeset is all done under console_lock, which means that _none_ of >> your BUG_ON will ever get out over serial console. >> >> The problem is fbcon locking, but no fool yet signed up to fix it (it's >> horrible, I looked ...). >> -Daniel > > I know this problem, if fbcon locking, and BUG_ON, we can't get any log from serial console, Trouble > me many times. So know, if no drm log output, the first thing I do is remove the fbcon lock, and then > we can see the crash dump. > > But here, I expect to use BUG_ON, because if BUG happen, vop register will hang system, and WARN_ON > may be have no chance to output. Yeah, but danvet is suggesting we just return immediately on the WARN_ON condition, to avoid accessing the vop registers and hanging. Thus, the WARN_ON will have a chance to put out (unless the early return path goes off and finds some other unprotected path goes to access unlocked registers). -Dan > > Mark >