Re: [PATCH V11 09/22] LoongArch: Add boot and setup routines

[Huacai Chen]

Hi, Javier,

On Sat, May 21, 2022 at 12:32 AM Javier Martinez Canillas
<javierm@xxxxxxxxxx> wrote:
>
> On 5/20/22 17:19, Huacai Chen wrote:
> > Hi, Javier,
>
> [snip]
>
> >> Conversely, if the sysfb_init() is executed first then the platform device
> >> will be registered and latter when the driver's init register the driver
> >> this will match the already registered device.
> > Yes, you are right, my consideration is too complex. The only real
> > problem is a harmless error "efifb: a framebuffer is already
> > registered" when both efifb and the native display driver are
> > built-in.
> >
>
> But this shouldn't be a problem if you drop your register_gop_device() that
> registers an "efi-framebuffer", since sysfb would either register a platform
> device "simple-framebufer" or "efi-framebuffer", but never both. Those are
> mutually exclusive.
>
> I think what's happening now is that sysfb is registering a "simple-framebuffer"
> but your register_gop_device() function is also registering an "efi-framebuffer".
No, I have already removed register_gop_device(). Now my problem is like this:
1, efifb (or simpledrm) is built-in;
2, a native display driver (such as radeon) is also built-in.

Because efifb, radeon and sysfb are all in device_initcall() level,
the order in practise is like this:

efifb registered at first, but no "efi-framebuffer" device yet.
radeon registered later, and /dev/fb0 created.
sysfb_init() comes at last, it registers "efi-framebuffer" and then
causes the error "efifb: a framebuffer is already registered".
make sysfb_init() to be subsys_initcall_sync() can avoid this.

Huacai

>
> --
> Best regards,
>
> Javier Martinez Canillas
> Linux Engineering
> Red Hat
>