Re: [patch 5/6] Convert to use mutexes instead of semaphores
- From: Richard Purdie <rpurdie@xxxxxxxxx>
- Date: Fri, 11 Aug 2006 14:16:09 +0100
On Fri, 2006-08-11 at 08:58 -0400, Dmitry Torokhov wrote:
On 8/11/06, Dmitry Torokhov <dtor@xxxxxxxxxxxxx> wrote:
Backlight: convert to use mutexes instead of semaphores
Apparently I missed that several drivers also use bd->sem so they need
to be converted too... But what is it with the drivers:
static void aty128_bl_set_power(struct fb_info *info, int power)
{
mutex_lock(&info->bl_mutex);
up(&info->bl_dev->sem);
info->bl_dev->props->power = power;
__aty128_bl_update_status(info->bl_dev);
down(&info->bl_dev->sem);
mutex_unlock(&info->bl_mutex);
}
Why we are doing up() before down()??? And it is in almost every
driver that uses backlight... Do I need more coffee? [CC-ing bunch of
people trying to get an answer...]
It looks totally wrong.
In the archives, there are a number of comments from me questioning
whether that driver needs to touch bl_dev->sem anyway (esp. given the
mutex as well). I never did find out what it was trying to protect
against...
Richard
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