Hi Florian,
On Sunday 20 November 2011 03:00:33 Florian Tobias Schandinat wrote:
> Hi Laurent,
>
> On 08/31/2011 11:18 AM, Laurent Pinchart wrote:
> > This API will be used to support YUV frame buffer formats in a standard
> > way.
>
> looks like the union is causing problems. With this patch applied I get
> errors like this:
>
> CC [M] drivers/auxdisplay/cfag12864bfb.o
> drivers/auxdisplay/cfag12864bfb.c:57: error: unknown field ‘red’ specified
> in initializer
*ouch*
gcc < 4.6 chokes on anonymous unions initializers :-/
[snip]
> > @@ -246,12 +251,23 @@ struct fb_var_screeninfo {
> >
> > __u32 yoffset; /* resolution */
> >
> > __u32 bits_per_pixel; /* guess what */
> >
> > - __u32 grayscale; /* != 0 Graylevels instead of colors */
> >
> > - struct fb_bitfield red; /* bitfield in fb mem if true color, */
> > - struct fb_bitfield green; /* else only length is significant */
> > - struct fb_bitfield blue;
> > - struct fb_bitfield transp; /* transparency */
> > + union {
> > + struct { /* Legacy format API */
> > + __u32 grayscale; /* 0 = color, 1 = grayscale */
> > + /* bitfields in fb mem if true color, else only */
> > + /* length is significant */
> > + struct fb_bitfield red;
> > + struct fb_bitfield green;
> > + struct fb_bitfield blue;
> > + struct fb_bitfield transp; /* transparency */
> > + };
> > + struct { /* FOURCC-based format API */
> > + __u32 fourcc; /* FOURCC format */
> > + __u32 colorspace;
> > + __u32 reserved[11];
> > + } fourcc;
> > + };
We can't name the union, otherwise this will change the userspace API.
We could "fix" the problem on the kernel side with
#ifdef __KERNEL__
} color;
#else
};
#endif
That's quite hackish though... What's your opinion ?
It would also not handle userspace code that initializes an fb_var_screeninfo
structure with named initializers, but that shouldn't happen, as application
should read fb_var_screeninfo , modify it and write it back.
> >
> > __u32 nonstd; /* != 0 Non standard pixel format */
--
Regards,
Laurent Pinchart
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