Re: [PATCH] fbdev driver for S3 Trio/Virge

Ondrej Zajicek napsal(a):

On Mon, Feb 05, 2007 at 11:33:12PM +0100, Jiri Slaby wrote:                                                            

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Ondrej Zajicek napsal(a):

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+#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.

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+		memset(&(par->state), 0, sizeof(struct vgastate));
+		par->state.flags = VGA_SAVE_MODE | VGA_SAVE_FONTS | VGA_SAVE_CMAP;
+		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.

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+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) + padding.
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?

regards,
-- 
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
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