Re: [PATCH] drm/hisilicon/hibmc: Move drm_fbdev_generic_setup() down to avoid the splat

From: Thomas Zimmermann <tzimmermann@suse.de>
To: Zenghui Yu <yuzenghui@huawei.com>,
	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,
	sam@ravnborg.org, wanghaibin.wang@huawei.com
Subject: Re: [PATCH] drm/hisilicon/hibmc: Move drm_fbdev_generic_setup() down to avoid the splat
Date: Mon, 6 Jul 2020 19:03:40 +0200	[thread overview]
Message-ID: <aa244201-9b43-2d35-c236-21391e7af7d0@suse.de> (raw)
In-Reply-To: <20200706144713.1123-1-yuzenghui@huawei.com>


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Hi

Am 06.07.20 um 16:47 schrieb Zenghui Yu:
> 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>

Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>

> ---
>  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:
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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