2014/1/3 Wolfram Sang [off-list ref]:

Hi,

thanks for the submission!

You're welcome :) Thanks for reviewing this.

quoted

--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c

@@ -58,6 +58,8 @@ static bool iic_force_fast;
 module_param(iic_force_fast, bool, 0);
 MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");

+#define FIFO_FLUSH_TIMEOUT 100

100 what? The unit is missing.

The actual value of this timeout isn't very important. This is used
only to avoid a never ending loop in case the hardware goes into a
really bad state.

quoted

@@ -167,8 +170,8 @@ static void iic_dev_init(struct ibm_iic_private* dev)
      /* Clear control register */
      out_8(&iic->cntl, 0);

-     /* Enable interrupts if possible */
-     iic_interrupt_mode(dev, dev->irq >= 0);
+     /* Start with each individual interrupt masked*/

Space at the end of comment missing

ok

quoted

 static irqreturn_t iic_handler(int irq, void *dev_id)
 {
-     struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
-     struct iic_regs __iomem *iic = dev->vaddr;
-
-     DBG2(dev, "irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
-          in_8(&iic->sts), in_8(&iic->extsts));
-
-     /* Acknowledge IRQ and wakeup iic_wait_for_tc */
-     out_8(&iic->sts, STS_IRQA | STS_SCMP);
-     wake_up_interruptible(&dev->wq);
-
+     struct ibm_iic_private *dev = (struct ibm_iic_private *) dev_id;
+     iic_xfer_bytes(dev);

Is iic_xfer_bytes later used when polling, too? Otherwise it could be
simply inserted here.

Yes it'll be used for polling (implemented in a later patch)

quoted

+     if ((status & STS_ERR) ||
+         (ext_status & (EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA))) {
+             DBG(dev, "status 0x%x\n", status);
+             DBG(dev, "extended status 0x%x\n", ext_status);
+             if (status & STS_ERR)
+                     ERR(dev, "Error detected\n");
+             if (ext_status & EXTSTS_LA)
+                     DBG(dev, "Lost arbitration\n");
+             if (ext_status & EXTSTS_ICT)
+                     ERR(dev, "Incomplete transfer\n");
+             if (ext_status & EXTSTS_XFRA)
+                     ERR(dev, "Transfer aborted\n");
+
+             dev->status = -EIO;

You could consider returning different fault codes for the different
states. See Documentation/i2c/fault-codes for a guide.

I'll have a look at it.

quoted

+     if (dev->msgs == NULL) {
+             DBG(dev, "spurious !!!!!\n");
+             dev->status = -EINVAL;
+             return dev->status;
+     }

Does that really happen?

Not in my test cases (going through i2c dev). But it could if the data
passed to i2c_transfer is malformed.
Should I remove this ?

And it introduces a build warning:

drivers/i2c/busses/i2c-ibm_iic.c:410:12: warning: 'iic_wait_for_tc' defined but not used [-Wunused-function]

I posted this some time ago, but I believe I kept this in to help git
produce a diff readable by a human.
It's removed in a later patch

Jean-Jacques