Subject: Re: [PATCH v3 REPOST 2/4] i2c: i2c-ibm-iic: perform the transfer in the interrupt handler

From: Wolfram Sang <[email-masked]>
Date: Fri, 3 Jan 2014 16:04:16 +0100

Hi,

thanks for the submission!

> --- 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.

> @@ -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

>  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.

> +	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.

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

Does that really happen?

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]