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SubjectRe: [PATCH] fbdev driver for S3 Trio/Virge
Ondrej Zajicek napsal(a):
> On Mon, Feb 05, 2007 at 11:33:12PM +0100, Jiri Slaby wrote:
>> Ondrej Zajicek napsal(a):
>>> +#ifdef CONFIG_MTRR
>>> +#include <asm/mtrr.h>
>>> +#endif
>> Why ifdef? It's ifdeffed in the header itself.
> But this header is only available on some archs, isn't it?

Yup, I stand corrected.

>>> + memset(&(par->state), 0, sizeof(struct vgastate));
>>> + par->state.flags = VGA_SAVE_MODE | VGA_SAVE_FONTS |
>>> + par->state.num_crtc = 0x70;
>>> + par->state.num_seq = 0x20;
>>> + save_vga(&(par->state));
>>> + }
>>> +
>>> + atomic_inc(&(par->ref_count));
>>> +
>>> + return 0;
>>> +}
> This pattern is in several fbdev drivers (neofb, i810fb, rivafb, vga16fb).
> I understand the problem but i am not sure what is the best solution.

Blah. It should be fixed, then.

> Maybe acquire/release console semaphore before/after s3fb_open?

Kick atomic_t-s off and use mutexes to protect simple uint or something like this.

>>> +static int s3fb_release(struct fb_info *info, int user)
>>> +{
>>> + struct s3fb_info *par = (struct s3fb_info *) info;
>> Use container_of for this (and below/above).
> Isn't container_of overkill for this case?

Hmm, maybe yes. Anyway it's not so clean way to do it.

I can see, they have void *par in fb_info. I would do:
struct s3fb_info {
int chip, rev, mclk_freq;
int mtrr_reg;
struct vgastate state;
atomic_t ref_count;
u32 pseudo_palette[16];
I.e. no struct fb_info inside, since you allocate the space twice by
framebuffer_alloc() -- 2*sizeof(struct fb_info) + sizeof(struct s3fb_info) +
Then normally
framebuffer_alloc(sizeof(struct s3fb_info), NULL);
and happily use
struct s3fb_info *s = info->par;
since par member is set directly to aligned space after fb_info when size is
nonzero inside the framebuffer_alloc().

Is there any problem with this approach?

-- Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E
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