PROBLEM: module i2c_pca_isa PC9564, interrupt problem

[alain meirhaeghe <ame@technord.com>]

Hello,
I think there is a bug in i2c_pca_isa driver.
Problem is interrupt running on arm720 system linux-2.6.20.1.

Description of the problem:
When driver write to pc9564 an infinite loop interrupt appear (bloquing 
the system).


J think it is because the acknowledge of interrupt is not do correctly.
Acknowledge of interrupt is done outside interrupt .
J think it is dangerous if latency time of interrupt is short (as in ARM 
processor).

See existing code below:
static int pca_isa_waitforinterrupt(struct i2c_algo_pca_data *adap)
{
   int ret = 0;
   if (irq > -1)
   {
       ret = wait_event_interruptible(pca_wait,pca_isa_readbyte(adap, 
I2C_PCA_CON) & I2C_PCA_CON_SI);
     
   } else
   {
       while ((pca_isa_readbyte(adap, I2C_PCA_CON) & I2C_PCA_CON_SI) == 0)
           udelay(100);
   }
   return ret;
}

static irqreturn_t pca_handler(int this_irq, void *dev_id) {
  
   wake_up_interruptible(&pca_wait);
   return IRQ_HANDLED;
}

Isa_wait is never waked because pca_handler is always call, because j 
think it is necessary to acknowledge the interrupt in the interrupt 
handler as usual.
My temporary solution is:
static irqreturn_t pca_handler(int this_irq, void *dev_id) {
   disable_irq(irq);   // !!!!!!!!!!!!!!!!!!! temporary patch
   wake_up_interruptible(&pca_wait);
   return IRQ_HANDLED;
}



How can we correct this  ?

Thank to all
Alain Meirhaeghe




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