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From:   Zenghui Yu <yuzenghui@huawei.com>
To:     <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
CC:     <xinliang.liu@linaro.org>, <zourongrong@gmail.com>,
        <john.stultz@linaro.org>, <kong.kongxinwei@hisilicon.com>,
        <puck.chen@hisilicon.com>, <airlied@linux.ie>, <daniel@ffwll.ch>,
        <tzimmermann@suse.de>, <sam@ravnborg.org>,
        <wanghaibin.wang@huawei.com>, Zenghui Yu <yuzenghui@huawei.com>
Subject: [PATCH] drm/hisilicon/hibmc: Move drm_fbdev_generic_setup() down to avoid the splat
Date:   Mon, 6 Jul 2020 22:47:13 +0800
Message-ID: <20200706144713.1123-1-yuzenghui@huawei.com>
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Sender: linux-kernel-owner@vger.kernel.org
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The HiSilicon hibmc driver triggers a splat at boot time as below

[   14.137806] ------------[ cut here ]------------
[   14.142405] hibmc-drm 0000:0a:00.0: Device has not been registered.
[   14.148661] WARNING: CPU: 0 PID: 496 at drivers/gpu/drm/drm_fb_helper.c:2233 drm_fbdev_generic_setup+0x15c/0x1b8
[   14.158787] [...]
[   14.278307] Call trace:
[   14.280742]  drm_fbdev_generic_setup+0x15c/0x1b8
[   14.285337]  hibmc_pci_probe+0x354/0x418
[   14.289242]  local_pci_probe+0x44/0x98
[   14.292974]  work_for_cpu_fn+0x20/0x30
[   14.296708]  process_one_work+0x1c4/0x4e0
[   14.300698]  worker_thread+0x2c8/0x528
[   14.304431]  kthread+0x138/0x140
[   14.307646]  ret_from_fork+0x10/0x18
[   14.311205] ---[ end trace a2000ec2d838af4d ]---

This turned out to be due to the fbdev device hasn't been registered when
drm_fbdev_generic_setup() is invoked. Let's fix the splat by moving it down
after drm_dev_register() which will follow the "Display driver example"
documented by commit de99f0600a79 ("drm/drv: DOC: Add driver example
code").

Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
index a6fd0c29e5b8..544b9993c99e 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
@@ -307,8 +307,6 @@ static int hibmc_load(struct drm_device *dev)
 	/* reset all the states of crtc/plane/encoder/connector */
 	drm_mode_config_reset(dev);
 
-	drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);
-
 	return 0;
 
 err:
@@ -355,6 +353,9 @@ static int hibmc_pci_probe(struct pci_dev *pdev,
 			  ret);
 		goto err_unload;
 	}
+
+	drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);
+
 	return 0;
 
 err_unload:
-- 
2.19.1