Messages in this thread | | | Subject | Re: [patch 5/6] Convert to use mutexes instead of semaphores | From | Richard Purdie <> | Date | Fri, 11 Aug 2006 14:16:09 +0100 |
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On Fri, 2006-08-11 at 08:58 -0400, Dmitry Torokhov wrote: > On 8/11/06, Dmitry Torokhov <dtor@insightbb.com> 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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