Re: [PATCH 3/4] i2c: imx: add macros and printk to make debug easy

Sascha Hauer
2009-10-01T08:26:10Z

On Thu, Oct 01, 2009 at 04:01:50PM +0800, Richard Zhao wrote:
> On Thu, Oct 1, 2009 at 3:29 PM, Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> wrote:
> > On Thu, Oct 01, 2009 at 09:13:32AM +0800, Richard Zhao wrote:
> >> When CONFIG_I2C_DEBUG_BUS is enabled, it helps dump registers at operation
> >> fail condition, and print i2c_msg to xfer.
> >>
> >> Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> >
> > Honestly I don't think we need this. It makes the driver too verbose for
> > my taste.
> >
> > Sascha
> >
> >
> >>
> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> >> index c1e541c..87faea4 100644
> >> --- a/drivers/i2c/busses/i2c-imx.c
> >> +++ b/drivers/i2c/busses/i2c-imx.c
> >> @@ -125,6 +125,20 @@ struct imx_i2c_struct {
> >>  /** Functions for IMX I2C adapter driver ***************************************
> >>  *******************************************************************************/
> >>
> >> +#ifdef CONFIG_I2C_DEBUG_BUS
> >> +#define reg_dump(i2c_imx) \
> >> +{ \
> >> +     printk(KERN_DEBUG "fun %s:%d ", __func__, __LINE__); \
> >> +     printk(KERN_DEBUG "IADR %02x IFDR %02x I2CR %02x I2SR %02x\n", \
> >> +             readb(i2c_imx->base + IMX_I2C_IADR), \
> >> +             readb(i2c_imx->base + IMX_I2C_IFDR), \
> >> +             readb(i2c_imx->base + IMX_I2C_I2CR), \
> >> +             readb(i2c_imx->base + IMX_I2C_I2SR)); \
> >> +}
> >> +#else
> >> +#define reg_dump(i2c_imx)
> >> +#endif
> >> +
> >>  static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
> >>  {
> >>       unsigned long orig_jiffies = jiffies;
> >> @@ -146,6 +160,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
> >>               if (time_after(jiffies, orig_jiffies + HZ / 1000)) {
> >>                       dev_dbg(&i2c_imx->adapter.dev,
> >>                               "<%s> I2C bus is busy\n", __func__);
> >> +                     reg_dump(i2c_imx);
> >>                       return -EIO;
> >>               }
> >>               schedule();
> >> @@ -164,9 +179,11 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
> >>
> >>       if (unlikely(result < 0)) {
> >>               dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__);
> >> +             reg_dump(i2c_imx);
> >>               return result;
> >>       } else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
> >>               dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
> >> +             reg_dump(i2c_imx);
> >>               return -ETIMEDOUT;
> >>       }
> >>       dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__);
> >> @@ -178,6 +195,7 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
> >>  {
> >>       if (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_RXAK) {
> >>               dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
> >> +             reg_dump(i2c_imx);
> >>               return -EIO;  /* No ACK */
> >>       }
> >>
> >> @@ -197,17 +215,20 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
> >>       writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
> >>
> >>       result = i2c_imx_bus_busy(i2c_imx, 0);
> >> -     if (result)
> >> +     if (result) {
> >> +             reg_dump(i2c_imx);
> >>               return result;
> >> +     }
> >>
> >>       /* Start I2C transaction */
> >>       temp = readb(i2c_imx->base + IMX_I2C_I2CR);
> >>       temp |= I2CR_MSTA;
> >>       writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
> >>       result = i2c_imx_bus_busy(i2c_imx, 1);
> >> -     if (result)
> >> +     if (result) {
> >> +             reg_dump(i2c_imx);
> >>               return result;
> >> -
> >> +     }
> >>       temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
> >>       writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
> >>       return result;
> >> @@ -228,7 +249,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
> >>        */
> >>       udelay(i2c_imx->disable_delay);
> >>
> >> -     i2c_imx_bus_busy(i2c_imx, 0);
> >> +     if (i2c_imx_bus_busy(i2c_imx, 0))
> >> +             reg_dump(i2c_imx);
> >>
> >>       /* Disable I2C controller */
> >>       writeb(0, i2c_imx->base + IMX_I2C_I2CR);
> >> @@ -389,7 +411,18 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
> >>       struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);
> >>
> >>       dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
> >> -
> >> +#ifdef CONFIG_I2C_DEBUG_BUS
> >> +     for (i = 0; i < num; i++) {
> >> +             printk(KERN_DEBUG "msg%d addr %02x RD %d cnt %d d:", i,
> >> +                     msgs[i].addr, msgs[i].flags & I2C_M_RD, msgs[i].len);
> >> +             if (!(msgs[i].flags & I2C_M_RD)) {
> >> +                     int j;
> >> +                     for (j = 0; j < msgs[i].len; j++)
> >> +                             printk("%02x ", msgs[i].buf[j]);
> >> +             }
> >> +             printk("\n");
> >> +     }
> >> +#endif
> >>       /* Start I2C transfer */
> >>       result = i2c_imx_start(i2c_imx);
> >>       if (result)
> >> @@ -404,8 +437,10 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
> >>                       temp |= I2CR_RSTA;
> >>                       writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
> >>                       result =  i2c_imx_bus_busy(i2c_imx, 1);
> >> -                     if (result)
> >> +                     if (result) {
> >> +                             reg_dump(i2c_imx);
> >>                               goto fail0;
> >> +                     }
> >>               }
> >>               dev_dbg(&i2c_imx->adapter.dev,
> >>                       "<%s> transfer message: %d\n", __func__, i);
> >> @@ -562,7 +597,7 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
> >>               res_size, i2c_imx->res->start);
> >>       dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"\n",
> >>               i2c_imx->adapter.name);
> >> -     dev_dbg(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
> >> +     dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
> >>
> >>       return 0;   /* Return OK */
> >>
> >> --
> >> 1.6.0.4
> >>
> >>
> >
> > --
> > Pengutronix e.K.                           |                             |
> > Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> > Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> > Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> >
>
> 1. i2c is more important bus in embedded system than PC. Many PMICs
> are connected to cpu via i2c. Before system boot up, we depend much on
> printk message.
> 2. When we add a new i2c device, it's easy to have problems. Maybe
> it's hw issue, one device fails, all ones in the same bus fails. In
> such condition, debug message is very helpfull.

The driver already consists to 15% of debug statements, there is
definitely no need to add even more. If anything, you could concentrate
on making the output more useful.

Sascha

--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |