On Tue, Sep 29, 2009 at 09:54:05PM +0800, Richard Zhao wrote: > Thanks, Sacha. See comments inline. > > On Tue, Sep 29, 2009 at 9:25 PM, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote: > > Hi Richard, > > > > > > On Tue, Sep 29, 2009 at 07:41:44PM +0800, Richard Zhao wrote: > >> After START, wait busy bit to be set and > >> after STOP, wait busy bit to be clear. > >> > >> Disable clock when it's possible to save power. > >> > >> Signed-off-by: Richard Zhao <linuxzsc@xxxxxxxxx> > >> --- > >> drivers/i2c/busses/i2c-imx.c | 116 ++++++++++++++++++++++++++++++++---------- > >> 1 files changed, 88 insertions(+), 28 deletions(-) > >> > >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > >> index 4afba3e..59cde70 100644 > >> --- a/drivers/i2c/busses/i2c-imx.c > >> +++ b/drivers/i2c/busses/i2c-imx.c > >> @@ -120,19 +120,40 @@ struct imx_i2c_struct { > >> wait_queue_head_t queue; > >> unsigned long i2csr; > >> unsigned int disable_delay; > >> + unsigned int ifdr; /* IMX_I2C_IFDR */ > >> }; > >> > >> /** Functions for IMX I2C adapter driver > >> *************************************** > >> *******************************************************************************/ > >> > >> -static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx) > >> +#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 > >> + > > > > Can you please remove this reg_dump? If we really need this it should be > > in an extra patch and not clutter this one. > I think it's needed. It helps much to debug and don't effect > performance by default. > > > >> +static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy) > >> { > >> unsigned long orig_jiffies = jiffies; > >> + unsigned int temp; > >> > >> dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); > >> > >> /* wait for bus not busy */ > > > > This comment seems wrong now. This function waits for busy or not busy > > depending on for_busy. > Right. Thanks > > > >> - while (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_IBB) { > >> + temp = readb(i2c_imx->base + IMX_I2C_I2SR); > >> + while (1) { > >> + if (for_busy && (temp & I2SR_IBB)) > >> + break; > >> + if (!for_busy && !(temp & I2SR_IBB)) > >> + break; > >> if (signal_pending(current)) { > >> dev_dbg(&i2c_imx->adapter.dev, > >> "<%s> I2C Interrupted\n", __func__); > >> @@ -141,9 +162,11 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx) > >> 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(); > >> + temp = readb(i2c_imx->base + IMX_I2C_I2SR); > >> } > >> > >> return 0; > >> @@ -158,9 +181,11 @@ 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__); > >> @@ -172,6 +197,7 @@ 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 */ > >> } > >> > >> @@ -179,20 +205,37 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx) > >> return 0; > >> } > >> > >> -static void i2c_imx_start(struct imx_i2c_struct *i2c_imx) > >> +static int i2c_imx_start(struct imx_i2c_struct *i2c_imx) > >> { > >> unsigned int temp = 0; > >> + int result; > >> > >> dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); > >> > >> + clk_enable(i2c_imx->clk); > >> + writeb(i2c_imx->ifdr, i2c_imx->base + IMX_I2C_IFDR); > >> /* Enable I2C controller */ > >> + writeb(0, i2c_imx->base + IMX_I2C_I2SR); > >> writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR); > >> + > >> + result = i2c_imx_bus_busy(i2c_imx, 0); > >> + 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) { > >> + reg_dump(i2c_imx); > >> + return result; > >> + } > >> temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK; > >> writeb(temp, i2c_imx->base + IMX_I2C_I2CR); > >> + return result; > >> } > >> > >> static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx) > >> @@ -202,18 +245,21 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx) > >> /* Stop I2C transaction */ > >> dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__); > >> temp = readb(i2c_imx->base + IMX_I2C_I2CR); > >> - temp &= ~I2CR_MSTA; > >> + temp &= ~(I2CR_MSTA | I2CR_MTX); > > > > This change seems unrelated. Is it necessary? > Yes. It's about STOP. It's better clear MTX. We must generate STOP > before read the last byte of Data register. If not, there will be an > extra 9bit clock. > > > >> writeb(temp, i2c_imx->base + IMX_I2C_I2CR); > >> - /* setup chip registers to defaults */ > >> - writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR); > >> - writeb(0, i2c_imx->base + IMX_I2C_I2SR); > >> /* > >> * This delay caused by an i.MXL hardware bug. > >> * If no (or too short) delay, no "STOP" bit will be generated. > >> */ > >> udelay(i2c_imx->disable_delay); > >> + > >> + > > > > double blank line > Right. > > > >> + if (i2c_imx_bus_busy(i2c_imx, 0)) > >> + reg_dump(i2c_imx); > >> + > >> /* Disable I2C controller */ > >> writeb(0, i2c_imx->base + IMX_I2C_I2CR); > >> + clk_disable(i2c_imx->clk); > >> } > >> > >> static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx, > >> @@ -233,17 +279,19 @@ static void __init i2c_imx_set_clk(struct > >> imx_i2c_struct *i2c_imx, > >> else > >> for (i = 0; i2c_clk_div[i][0] < div; i++); > >> > >> - /* Write divider value to register */ > >> - writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR); > > > > Why can't we write this value directly anymore... > clock will be enable/disable in start/stop > > > >> - > >> - /* > >> - * There dummy delay is calculated. > >> - * It should be about one I2C clock period long. > >> - * This delay is used in I2C bus disable function > >> - * to fix chip hardware bug. > >> - */ > >> - i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0] > >> - + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2); > >> + /* Store divider value */ > >> + i2c_imx->ifdr = i2c_clk_div[i][1]; > > > > ...but have to store it in a variable instead? > To save power, because i2c is not aways be accessed, and it's very low > speed bus. > > > >> + > >> + if (cpu_is_mx1()) { > >> + /* > >> + * There dummy delay is calculated. > >> + * It should be about one I2C clock period long. > >> + * This delay is used in I2C bus disable function > >> + * to fix chip hardware bug. > >> + */ > >> + i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0] > >> + + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2); > >> + } > >> > >> /* dev_dbg() can't be used, because adapter is not yet registered */ > >> #ifdef CONFIG_I2C_DEBUG_BUS > >> @@ -344,7 +392,7 @@ static int i2c_imx_read(struct imx_i2c_struct > >> *i2c_imx, struct i2c_msg *msgs) > >> dev_dbg(&i2c_imx->adapter.dev, > >> "<%s> clear MSTA\n", __func__); > >> temp = readb(i2c_imx->base + IMX_I2C_I2CR); > >> - temp &= ~I2CR_MSTA; > >> + temp &= ~(I2CR_MSTA | I2CR_MTX); > >> writeb(temp, i2c_imx->base + IMX_I2C_I2CR); > >> } else if (i == (msgs->len - 2)) { > >> dev_dbg(&i2c_imx->adapter.dev, > >> @@ -369,14 +417,24 @@ 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 > >> /* Check if i2c bus is not busy */ > >> - result = i2c_imx_bus_busy(i2c_imx); > >> - if (result) > >> - goto fail0; > > > > When removing the code you should also remove the comment. > Right > > > >> > >> /* Start I2C transfer */ > >> - i2c_imx_start(i2c_imx); > >> + result = i2c_imx_start(i2c_imx); > >> + if (result) > >> + goto fail0; > >> > >> /* read/write data */ > >> for (i = 0; i < num; i++) { > >> @@ -386,6 +444,11 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter, > >> temp = readb(i2c_imx->base + IMX_I2C_I2CR); > >> temp |= I2CR_RSTA; > >> writeb(temp, i2c_imx->base + IMX_I2C_I2CR); > >> + result = i2c_imx_bus_busy(i2c_imx, 1); > >> + if (result) { > >> + reg_dump(i2c_imx); > >> + goto fail0; > >> + } > >> } > >> dev_dbg(&i2c_imx->adapter.dev, > >> "<%s> transfer message: %d\n", __func__, i); > >> @@ -442,7 +505,7 @@ static int __init i2c_imx_probe(struct > >> platform_device *pdev) > >> int irq; > >> int ret; > >> > >> - dev_dbg(&pdev->dev, "<%s>\n", __func__); > >> + dev_info(&pdev->dev, "<%s>\n", __func__); > > > > no > Why? I even don't know how many i2c controllers we have, if I didn't > get sysfs working. And it only print once. > > > >> > >> res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > >> if (!res) { > >> @@ -500,7 +563,6 @@ static int __init i2c_imx_probe(struct > >> platform_device *pdev) > >> dev_err(&pdev->dev, "can't get I2C clock\n"); > >> goto fail3; > >> } > >> - clk_enable(i2c_imx->clk); > > > > I think it's generally a good idea to start/stop the clocks when needed > > as you do here. It should be an extra patch though. > You think I should split the patch to three: IBB, reg_dump, clk dis/en ? > The idea is good, more easy to revert. but sometimes, I think it make > small things too complex. > Anyway, I'll follow your suggestion. In case of regressions everybody will thank you for doing it. 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 | -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html