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[92.176.231.205]) by smtp.gmail.com with ESMTPSA id q184-20020a1c43c1000000b003a302fb9df7sm13972584wma.21.2022.07.24.02.06.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 24 Jul 2022 02:06:25 -0700 (PDT) Message-ID: <7dc80ce9-83d5-2dc2-f660-fb8f6162c893@redhat.com> Date: Sun, 24 Jul 2022 11:06:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] drm/msm: Make .remove and .shutdown HW shutdown consistent Content-Language: en-US To: Dmitry Baryshkov Cc: linux-kernel@vger.kernel.org, Abhinav Kumar , Daniel Vetter , David Airlie , Rob Clark , Sean Paul , dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org References: <20220723210825.564922-1-javierm@redhat.com> From: Javier Martinez Canillas In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 7/24/22 10:53, Dmitry Baryshkov wrote: > On Sun, 24 Jul 2022 at 00:09, Javier Martinez Canillas [...] >> - >> /* >> * Shutdown the hw if we're far enough along where things might be on. >> * If we run this too early, we'll end up panicking in any variety of >> @@ -205,10 +199,21 @@ static int msm_drm_uninit(struct device *dev) >> * msm_drm_init, drm_dev->registered is used as an indicator that the >> * shutdown will be successful. >> */ >> - if (ddev->registered) { >> + if (dev->registered) >> + drm_atomic_helper_shutdown(dev); >> +} >> + >> +static int msm_drm_uninit(struct device *dev) >> +{ >> + struct platform_device *pdev = to_platform_device(dev); >> + struct msm_drm_private *priv = platform_get_drvdata(pdev); >> + struct drm_device *ddev = priv->dev; >> + struct msm_kms *kms = priv->kms; >> + int i; >> + >> + if (ddev->registered) >> drm_dev_unregister(ddev); > > No. The drm_dev_unregister() should come before drm_atomic_helper_shutdown(). > I'm not sure to understand what you meant here, since drm_dev_unregister() is called before drm_atomic_helper_shutdown() that's called in msm_shutdown_hw(). > Also drm_dev_unregister() should not be a part of .shutdown callback. > See the documentation in the drm_drv.c > It is not right now, msm_shutdown_hw() only calls drm_atomic_helper_shutdown() but drm_dev_unregister() is still called from the msm_drm_uninit() function. Now, your comment made me realize that there's a bug in this patch since after the drm_dev_unregister(), dev->registered will be set to false and so in the .remove -> .unbind path drm_atomic_helper_shutdown() will never be executed. I guess one option is to do the if (dev->registered) check in the callers but then it won't really be worth it to have a helper and we could just add that check in msm_drv_shutdown() to conditionally call drm_atomic_helper_shutdown(). -- Best regards, Javier Martinez Canillas Linux Engineering Red Hat