From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751666AbdBYBZb (ORCPT ); Fri, 24 Feb 2017 20:25:31 -0500 Received: from mail-pg0-f41.google.com ([74.125.83.41]:36558 "EHLO mail-pg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751639AbdBYBZa (ORCPT ); Fri, 24 Feb 2017 20:25:30 -0500 From: John Stultz To: lkml Cc: John Stultz , Xinliang Liu , Rongrong Zou , Xinwei Kong , Chen Feng , David Airlie , Daniel Vetter , Sean Paul , dri-devel@lists.freedesktop.org Subject: [RFC][PATCH v2] drm: kirin: Add a mutex to avoid fb initialization race Date: Fri, 24 Feb 2017 17:25:16 -0800 Message-Id: <1487985916-29450-1-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 initialization happening twice. This could cause the system to boot up with a blank screen. This patch adds a simple mutex to serialize it and seems to avoid the race. Suggestions or feedback would be greatly appreciated! Cc: Xinliang Liu Cc: Rongrong Zou Cc: Xinwei Kong Cc: Chen Feng Cc: David Airlie Cc: Daniel Vetter Cc: Sean Paul Cc: dri-devel@lists.freedesktop.org Signed-off-by: John Stultz --- drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c | 4 ++++ drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h | 1 + 2 files changed, 5 insertions(+) diff --git a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c index 7ec93ae..b83556a 100644 --- a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c +++ b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c @@ -55,6 +55,7 @@ static void kirin_fbdev_output_poll_changed(struct drm_device *dev) { struct kirin_drm_private *priv = dev->dev_private; + mutex_lock(&priv->fb_lock); if (priv->fbdev) { drm_fbdev_cma_hotplug_event(priv->fbdev); } else { @@ -63,6 +64,7 @@ static void kirin_fbdev_output_poll_changed(struct drm_device *dev) if (IS_ERR(priv->fbdev)) priv->fbdev = NULL; } + mutex_unlock(&priv->fb_lock); } #endif @@ -95,6 +97,8 @@ static int kirin_drm_kms_init(struct drm_device *dev) if (!priv) return -ENOMEM; + mutex_init(&priv->fb_lock); + dev->dev_private = priv; dev_set_drvdata(dev->dev, dev); diff --git a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h index 7f60c649..9b6d2b1 100644 --- a/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h +++ b/drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.h @@ -23,6 +23,7 @@ struct kirin_drm_private { #ifdef CONFIG_DRM_FBDEV_EMULATION struct drm_fbdev_cma *fbdev; #endif + struct mutex fb_lock; }; extern const struct kirin_dc_ops ade_dc_ops; -- 2.7.4