Re: Patch to add mode setting to sysfs

["Antonino A. Daplas" <adaplas@hotpop.com>]

On Friday 18 February 2005 04:49, Jon Smirl wrote:
> On Thu, 17 Feb 2005 21:50:16 +0800, Antonino A. Daplas
>
> <adaplas@hotpop.com> wrote:
> > Instead of hardcoding some of the fields in var, why not
> > copy it from the current var?  Ie:
> >
> > var = info->var;
> > fb_videomode_to_var(&var, mode);
>
> I added this change, plus more robust error handing. Add attributes
> for virtual resolution and bpp.
>
> I also fixed fb so that it works as module.

If possible, separate the sysfs patch from making fbcore as module.

+static ssize_t store_modes(struct class_device *class_device, const
char * buf, size_t count)
+{
+       struct fb_info *fb_info = (struct fb_info *)class_get_devdata(class_device);
+       int i = count / sizeof(struct fb_videomode);
+       if (i * sizeof(struct fb_videomode) != count)
+               return -EINVAL;
+
+       fb_destroy_modelist(&fb_info->modelist);

This is dangerous.  For one, if the mode in info->var does not match any of
the entries in the modelist, you can get a screwed up display.  Secondly,
fbcon refers to info->modelist to store settings for each console.  Thus
it is better to check first if the mode in the modelist is currently in use.

A safer way is to loop through each entries of the old modelist, call 
fb_set_var() with the FB_ACTIVATE_INV_MODE set in var->activate. This
process will safely remove each mode from the modelist.  Not all entries
will be deleted of course. After that, loop through each entries of the new
modedb array, and use fb_add_videomode() to add each entry to the modelist.

Tony




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