From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751595AbdBYBZH (ORCPT <rfc822;w@1wt.eu>);
        Fri, 24 Feb 2017 20:25:07 -0500
Received: from szxga01-in.huawei.com ([45.249.212.187]:2846 "EHLO
        dggrg01-dlp.huawei.com" rhost-flags-OK-FAIL-OK-FAIL)
        by vger.kernel.org with ESMTP id S1751473AbdBYBZE (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 24 Feb 2017 20:25:04 -0500
Subject: Re: [RFC][PATCH] drm: kirin: Add a mutex to avoid fb initialization
 race
To: John Stultz <john.stultz@linaro.org>
References: <1487811383-6915-1-git-send-email-john.stultz@linaro.org>
 <58AF92A3.2040200@hisilicon.com>
 <CALAqxLVsO7JP+j1wSy_mM_Rf5S7Hx4Dueco6LD4qcqdDMAjv2A@mail.gmail.com>
CC: lkml <linux-kernel@vger.kernel.org>,
        Rongrong Zou <zourongrong@gmail.com>,
        Xinwei Kong <kong.kongxinwei@hisilicon.com>,
        Chen Feng <puck.chen@hisilicon.com>, David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Sean Paul <seanpaul@chromium.org>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>
From: liuxinliang <z.liuxinliang@hisilicon.com>
Message-ID: <58B0DC3A.4060707@hisilicon.com>
Date: Sat, 25 Feb 2017 09:22:02 +0800
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101
 Thunderbird/38.5.0
MIME-Version: 1.0
In-Reply-To: <CALAqxLVsO7JP+j1wSy_mM_Rf5S7Hx4Dueco6LD4qcqdDMAjv2A@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: 7bit
X-Originating-IP: [10.46.44.48]
X-CFilter-Loop: Reflected
X-Mirapoint-Virus-RAPID-Raw: score=unknown(0),
        refid=str=0001.0A020202.58B0DC33.0013,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0,
        ip=0.0.0.0,
        so=2014-11-16 11:51:01,
        dmn=2013-03-21 17:37:32
X-Mirapoint-Loop-Id: d9f8332d6f1d91eafc558fe9ff26db3b
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org



On 2017/2/25 5:33, John Stultz wrote:
> On Thu, Feb 23, 2017 at 5:55 PM, liuxinliang
> <z.liuxinliang@hisilicon.com> wrote:
>> Hi John,
>>
>> On 2017/2/23 8:56, John Stultz wrote:
>>> In some cases I've been seeing a race where two framebuffers
>>> would be initialized, as kirin_fbdev_output_poll_changed()
>>> might get called quickly in succession, resulting in the fb
>>> initialization happening twice. This could cause the system
>>
>> I might understand this race. This because two places call
>> drm_helper_hpd_irq_event might cause the race:
>> One place is here
>> static int kirin_drm_kms_init(struct drm_device *dev)
>> {
>> ...
>>      /* force detection after connectors init */
>>      (void)drm_helper_hpd_irq_event(dev);
>> ...
>> }
>>
>> another is the adv7533 interrupt thread handler
>> static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd)
>> {
>> ...
>>      if (process_hpd && irq0 & ADV7511_INT0_HPD && adv7511->bridge.encoder)
>>          drm_helper_hpd_irq_event(adv7511->connector.dev);
>> ...
>> }
>>
>> right?
>>
>> I don't get a better way to fix this yet , I like to put fb_lock into
>> kirin_drm_private.
> Ok. I've moved the mutex to the kirin_drm_private structure.
>
> Anything else you'd like to see before I resend?

Thanks, no more then.


Best,
-xinliang

>
> thanks
> -john
>
> .
>