From nobody Mon May 25 03:53:09 2026 Received: from cstnet.cn (smtp21.cstnet.cn [159.226.251.21]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8EF7D3F54D0; Tue, 19 May 2026 09:24:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.21 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779182685; cv=none; b=c6RbQ36375nVtpszLs7ztE0GE9d03rkqFTtlBZ5QrLfsdnHX8WDyxfmsORCEtpQ1CPNFT1jfeUEGXRLs8V8DtYctgvYQTDQ5Omx5xDEy0oo9/Vb2IMh/urm5YPXHh9PELw+0xndiqCsYMvppLk0acPm3sbst/M2ev55b7KHtCpc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779182685; c=relaxed/simple; bh=JJ1/equMYm7nVfvvibccLA9XJV+g6SrPVvB04YdTxqg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=B6WEpjV7lT9rRUuJxrAWj9oOYi/DFF0SynTNNQtuGy1NwRARrbonIw1gpuVo3YdlivITLJDebfJffc+iWGyJvIFJKgm6vp8WbmQKhnmU80Y4rtHMRAxmsiDtBGgZjF2nXiXaR9XT5ukXF+bUX7KVAvezhML7m/vpmdWlSUqx+mw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from edelgard.fodlan.icenowy.me (unknown [112.94.102.150]) by APP-01 (Coremail) with SMTP id qwCowAAnzGdFLAxqTtTAEA--.55S2; Tue, 19 May 2026 17:24:22 +0800 (CST) From: Icenowy Zheng To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Sam Ravnborg Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Icenowy Zheng , Icenowy Zheng , stable@vger.kernel.org Subject: [PATCH] drm/client: check whether CRTC is active before waiting for vblank Date: Tue, 19 May 2026 17:24:20 +0800 Message-ID: <20260519092420.1124348-1-zhengxingda@iscas.ac.cn> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qwCowAAnzGdFLAxqTtTAEA--.55S2 X-Coremail-Antispam: 1UD129KBjvJXoW7ZF1rXry3JFWkCw4rXFyfXrb_yoW8ur17pF 43GryYyFWktFZxKanrZa4xZF1FgayrJFWxGry7Kwnxu3Z0vwnFyryFyr9FgFW7Jr9xXay7 Xr4UtFy5uF1UCF7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9j14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26ryj6F1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s 0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xII jxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr 1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8cxa n2IY04v7MxkF7I0En4kS14v26r1q6r43MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4 AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE 17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMI IF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4l IxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvf C2KfnxnUUI43ZEXa7VUbGQ6JUUUUU== X-CM-SenderInfo: x2kh0wp0lqwv3d6l2u1dvotugofq/ Content-Type: text/plain; charset="utf-8" Currently the implementaion of drm_client_modeset_wait_for_vblank() assumes drm_vblank_get() will fail when the CRTC isn't active. However it seems that this is not true, and running fbcon on a device with the first CRTC inactive will lead to kernel warning in some cases (which could be reproduced with the loongson driver). Change the implementation to add a check for the active state (atomic) / enabled state (non-atomic) before calling drm_vblank_get(). As the assumption of drm_vblank_get() failing for inactive CRTC isn't met, the error status of drm_vblank_get() can now be exported too. Cc: stable@vger.kernel.org Fixes: d8c4bddcd8bc ("drm/fb-helper: Synchronize dirty worker with vblank") Signed-off-by: Icenowy Zheng --- drivers/gpu/drm/drm_client_modeset.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_cli= ent_modeset.c index bb49b8361271a..1b03bf351256e 100644 --- a/drivers/gpu/drm/drm_client_modeset.c +++ b/drivers/gpu/drm/drm_client_modeset.c @@ -1310,7 +1310,7 @@ int drm_client_modeset_wait_for_vblank(struct drm_cli= ent_dev *client, unsigned i { struct drm_device *dev =3D client->dev; struct drm_crtc *crtc; - int ret; + int ret =3D 0; =20 /* * Rate-limit update frequency to vblank. If there's a DRM master @@ -1326,15 +1326,24 @@ int drm_client_modeset_wait_for_vblank(struct drm_c= lient_dev *client, unsigned i * Only wait for a vblank event if the CRTC is enabled, otherwise * just don't do anything, not even report an error. */ + if (drm_drv_uses_atomic_modeset(dev)) { + if (!crtc->state || !crtc->state->active) + goto out; + } else { + if (!crtc->enabled) + goto out; + } + ret =3D drm_crtc_vblank_get(crtc); if (!ret) { drm_crtc_wait_one_vblank(crtc); drm_crtc_vblank_put(crtc); } =20 +out: drm_master_internal_release(dev); =20 - return 0; + return ret; } EXPORT_SYMBOL(drm_client_modeset_wait_for_vblank); =20 --=20 2.52.0