[PATCH] ppc32: move powermac backlight stuff to a workqueue

From: Benjamin Herrenschmidt (benh_at_kernel.crashing.org)
Date: 03/11/05

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    To: Andrew Morton <akpm@osdl.org>
Date:	Fri, 11 Mar 2005 16:39:53 +1100

    Hi !

    The powermac has a kernel-based driver for controlling the backlight
    from the keyboard that used to call into some fbdev's from interrupt
    contexts. This patch moves it to a workqueue (and additionally makes
    sure the console semaphore is taken and held).

    I hope I'll replace this by the new backlight framework in a future
    kernel version, but for now, this will fix the immediate issues with
    radeon.

    Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

    Index: linux-work/arch/ppc/platforms/pmac_backlight.c
    ===================================================================
    --- linux-work.orig/arch/ppc/platforms/pmac_backlight.c 2005-01-24 17:09:23.000000000 +1100
    +++ linux-work/arch/ppc/platforms/pmac_backlight.c 2005-03-11 15:18:54.000000000 +1100
    @@ -25,14 +25,19 @@
     #include <linux/adb.h>
     #include <linux/pmu.h>
     
    -static struct backlight_controller *backlighter = NULL;
    -static void* backlighter_data = NULL;
    -static int backlight_autosave = 0;
    +static struct backlight_controller *backlighter;
    +static void* backlighter_data;
    +static int backlight_autosave;
     static int backlight_level = BACKLIGHT_MAX;
     static int backlight_enabled = 1;
    +static int backlight_req_level = -1;
    +static int backlight_req_enable = -1;
     
    -void __pmac
    -register_backlight_controller(struct backlight_controller *ctrler, void *data, char *type)
    +static void backlight_callback(void *);
    +static DECLARE_WORK(backlight_work, backlight_callback, NULL);
    +
    +void __pmac register_backlight_controller(struct backlight_controller *ctrler,
    + void *data, char *type)
     {
             struct device_node* bk_node;
             char *prop;
    @@ -83,16 +88,18 @@
                     backlight_level = req.reply[0] >> 4;
             }
     #endif
    + acquire_console_sem();
             if (!backlighter->set_enable(1, backlight_level, data))
                     backlight_enabled = 1;
    + release_console_sem();
     
    - printk(KERN_INFO "Registered \"%s\" backlight controller, level: %d/15\n",
    - type, backlight_level);
    + printk(KERN_INFO "Registered \"%s\" backlight controller,"
    + "level: %d/15\n", type, backlight_level);
     }
     EXPORT_SYMBOL(register_backlight_controller);
     
    -void __pmac
    -unregister_backlight_controller(struct backlight_controller *ctrler, void *data)
    +void __pmac unregister_backlight_controller(struct backlight_controller
    + *ctrler, void *data)
     {
             /* We keep the current backlight level (for now) */
             if (ctrler == backlighter && data == backlighter_data)
    @@ -100,22 +107,29 @@
     }
     EXPORT_SYMBOL(unregister_backlight_controller);
     
    -int __pmac
    -set_backlight_enable(int enable)
    +static int __pmac __set_backlight_enable(int enable)
     {
             int rc;
     
             if (!backlighter)
                     return -ENODEV;
    - rc = backlighter->set_enable(enable, backlight_level, backlighter_data);
    + acquire_console_sem();
    + rc = backlighter->set_enable(enable, backlight_level,
    + backlighter_data);
             if (!rc)
                     backlight_enabled = enable;
    + release_console_sem();
             return rc;
     }
    +int __pmac set_backlight_enable(int enable)
    +{
    + backlight_req_enable = enable;
    + schedule_work(&backlight_work);
    +}
    +
     EXPORT_SYMBOL(set_backlight_enable);
     
    -int __pmac
    -get_backlight_enable(void)
    +int __pmac get_backlight_enable(void)
     {
             if (!backlighter)
                     return -ENODEV;
    @@ -123,8 +137,7 @@
     }
     EXPORT_SYMBOL(get_backlight_enable);
     
    -int __pmac
    -set_backlight_level(int level)
    +static int __pmac __set_backlight_level(int level)
     {
             int rc = 0;
     
    @@ -134,10 +147,12 @@
                     level = BACKLIGHT_OFF;
             if (level > BACKLIGHT_MAX)
                     level = BACKLIGHT_MAX;
    + acquire_console_sem();
             if (backlight_enabled)
                     rc = backlighter->set_level(level, backlighter_data);
             if (!rc)
                     backlight_level = level;
    + release_console_sem();
             if (!rc && !backlight_autosave) {
                     level <<=1;
                     if (level & 0x10)
    @@ -146,13 +161,35 @@
             }
             return rc;
     }
    +int __pmac set_backlight_level(int level)
    +{
    + backlight_req_level = level;
    + schedule_work(&backlight_work);
    +}
    +
     EXPORT_SYMBOL(set_backlight_level);
     
    -int __pmac
    -get_backlight_level(void)
    +int __pmac get_backlight_level(void)
     {
             if (!backlighter)
                     return -ENODEV;
             return backlight_level;
     }
     EXPORT_SYMBOL(get_backlight_level);
    +
    +static void backlight_callback(void *dummy)
    +{
    + int level, enable;
    +
    + do {
    + level = backlight_req_level;
    + enable = backlight_req_enable;
    + mb();
    +
    + if (level >= 0)
    + __set_backlight_level(level);
    + if (enable >= 0)
    + __set_backlight_enable(enable);
    + } while(cmpxchg(&backlight_req_level, level, -1) != level ||
    + cmpxchg(&backlight_req_enable, enable, -1) != enable);
    +}

    -
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