RE: 答复: [RESEND 1/3] drm: fsl-dcu: Fix no fb check bug

[Meng Yi]

Hi, Daniel
	Thanks for your clarification, and I will fix this error.
--
Meng

-----Original Message-----
From: Daniel Stone [mailto:daniel at fooishbar.org] 
Sent: Friday, January 01, 2016 11:10 PM
To: Meng Yi <meng.yi at nxp.com>
Cc: Stefan Agner <stefan at agner.ch>; dri-devel at lists.freedesktop.org; Yi Meng-B56799 <B56799 at freescale.com>
Subject: Re: 答复: [RESEND 1/3] drm: fsl-dcu: Fix no fb check bug

Hi,

On 30 December 2015 at 07:37, Meng Yi <meng.yi at nxp.com> wrote:
> I have tested your patch, It seems good to me.
> But I think state->fb check is still necessary, because fb is related to crtc , and panel is related to connector,. When fsl,panel is not valid, it indicate that connector is not available, but fb check is still needed. But I am not so sure, and what do you think?

fb is tied to planes. Planes are tied to CRTCs. CRTCs are tied to connectors. Connectors are tied to the panel. If the panel is not found, no connectors will be activated, so no CRTCs will be enabled, so no planes will be enabled.

Please let me be very clear though: setting fb == NULL is legitimate.
Userspace may do this at any time. Crashing when plane->state->fb == NULL is an error in your driver and must be fixed.

Cheers,
Daniel