target/linux/s3c24xx/patches-2.6.26/0164-fix-pcf50633-interrupt-work-enforce-wait-on-resume-c.patch

   1 From 3cb0a576425bdd2cb9b8f48f9fe39c01dfc18bbf Mon Sep 17 00:00:00 2001
   2 From: Andy Green <andy@openmoko.com>
   3 Date: Fri, 25 Jul 2008 23:06:12 +0100
   4 Subject: [PATCH] fix-pcf50633-interrupt-work-enforce-wait-on-resume-completion.patch
   5
   6 Improve pcf50633 interrupt service scheduling to enforce only servicing
   7 when resume action is completed
   8
   9 Signed-off-by: Andy Green <andy@openmoko.com>
  10 ---
  11  drivers/i2c/chips/pcf50633.c |   67 ++++++++++++++++++++++++++++++------------
  12  1 files changed, 48 insertions(+), 19 deletions(-)
  13
  14 diff --git a/drivers/i2c/chips/pcf50633.c b/drivers/i2c/chips/pcf50633.c
  15 index 82ee2f0..5c9d209 100644
  16 --- a/drivers/i2c/chips/pcf50633.c
  17 +++ b/drivers/i2c/chips/pcf50633.c
  18 @@ -656,6 +656,26 @@ static void pcf50633_work(struct work_struct *work)
  19
  20         mutex_lock(&pcf->working_lock);
  21         pcf->working = 1;
  22 +
  23 +       dev_info(&pcf->client.dev, "pcf50633_work called with suspended = %d\n",
  24 +                                  pcf->have_been_suspended);
  25 +
  26 +       /*
  27 +        * If we are inside suspend -> resume completion time we don't attempt
  28 +        * service until we have fully resumed.  Although we could talk to the
  29 +        * device as soon as I2C is up, the regs in the device which we might
  30 +        * choose to modify as part of the service action have not been
  31 +        * reloaded with their pre-suspend states yet.  Therefore we will
  32 +        * defer our service if we are called like that until our resume has
  33 +        * completed.
  34 +        */
  35 +
  36 +       if (pcf->have_been_suspended && (pcf->have_been_suspended < 2)) {
  37 +               dev_info(&pcf->client.dev, "rescheduling,  suspended = %d\n",
  38 +                                          pcf->have_been_suspended);
  39 +               goto reschedule;
  40 +       }
  41 +
  42         /*
  43          * datasheet says we have to read the five IRQ
  44          * status regs in one transaction
  45 @@ -663,30 +683,25 @@ static void pcf50633_work(struct work_struct *work)
  46         ret = i2c_smbus_read_i2c_block_data(&pcf->client, PCF50633_REG_INT1, 5,
  47                                             pcfirq);
  48         if (ret != 5) {
  49 -               DEBUGP("Oh crap PMU IRQ register read failed -- "
  50 -                      "retrying later %d\n", ret);
  51 +               dev_info(&pcf->client.dev,
  52 +                        "Oh crap PMU IRQ register read failed -- "
  53 +                        "retrying later %d\n", ret);
  54                 /*
  55 -                * this situation can happen during resume, just defer
  56 -                * handling the interrupt until enough I2C is up we can
  57 -                * actually talk to the PMU.  We can't just ignore this
  58 -                * because we are on a falling edge interrupt and our
  59 -                * PMU interrupt source does not clear until we read these
  60 -                * interrupt source registers.
  61 +                * it shouldn't fail, we no longer attempt to use I2C while
  62 +                * it can be suspended.  But we don't have much option but to
  63 +                * retry if if it ever did fail, because if we don't service
  64 +                * the interrupt to clear it, we will never see another PMU
  65 +                * interrupt edge.
  66                  */
  67 -               if (!schedule_work(&pcf->work) && !pcf->working)
  68 -                       dev_dbg(&pcf->client.dev, "work item may be lost\n");
  69 -
  70 -               /* we don't put the device here, hold it for next time */
  71 -               mutex_unlock(&pcf->working_lock);
  72 -               /* don't spew, delaying whatever else is happening */
  73 -               msleep(1);
  74 -               return;
  75 +               goto reschedule;
  76         }
  77
  78         /* hey did we just resume? */
  79
  80         if (pcf->have_been_suspended) {
  81 +               /* resume is officially over now then */
  82                 pcf->have_been_suspended = 0;
  83 +
  84                 /*
  85                  * grab a copy of resume interrupt reasons
  86                  * from pcf50633 POV
  87 @@ -1044,6 +1059,19 @@ static void pcf50633_work(struct work_struct *work)
  88         input_sync(pcf->input_dev);
  89         put_device(&pcf->client.dev);
  90         mutex_unlock(&pcf->working_lock);
  91 +
  92 +       return;
  93 +
  94 +reschedule:
  95 +       /* don't spew, delaying whatever else is happening */
  96 +       msleep(100);
  97 +
  98 +       dev_info(&pcf->client.dev, "rescheduling interrupt service\n");
  99 +       if (!schedule_work(&pcf->work))
 100 +               dev_err(&pcf->client.dev, "int service reschedule failed\n");
 101 +
 102 +       /* we don't put the device here, hold it for next time */
 103 +       mutex_unlock(&pcf->working_lock);
 104  }
 105
 106  static irqreturn_t pcf50633_irq(int irq, void *_pcf)
 107 @@ -1051,10 +1079,11 @@ static irqreturn_t pcf50633_irq(int irq, void *_pcf)
 108         struct pcf50633_data *pcf = _pcf;
 109
 110         DEBUGP("entering(irq=%u, pcf=%p): scheduling work\n", irq, _pcf);
 111 +       dev_info(&pcf->client.dev, "pcf50633_irq scheduling work\n");
 112
 113         get_device(&pcf->client.dev);
 114         if (!schedule_work(&pcf->work) && !pcf->working)
 115 -               dev_dbg(&pcf->client.dev, "work item may be lost\n");
 116 +               dev_err(&pcf->client.dev, "work item may be lost\n");
 117
 118         return IRQ_HANDLED;
 119  }
 120 @@ -2234,9 +2263,9 @@ static int pcf50633_suspend(struct device *dev, pm_message_t state)
 121  int pcf50633_ready(struct pcf50633_data *pcf)
 122  {
 123         if (!pcf)
 124 -               return -EBUSY;
 125 +               return -EACCES;
 126
 127 -       if (pcf->have_been_suspended)
 128 +       if (pcf->have_been_suspended && (pcf->have_been_suspended < 3))
 129                 return -EBUSY;
 130
 131         return 0;
 132 --
 133 1.5.6.3
 134