* [PATCH 1/4] i2c: imx: check busy bit when START/STOP
@ 2009-09-30 5:55 Richard Zhao
[not found] ` <1254290106-29272-1-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
0 siblings, 1 reply; 12+ messages in thread
From: Richard Zhao @ 2009-09-30 5:55 UTC (permalink / raw)
To: kernel-bIcnvbaLZ9MEGnE8C9+IrQ
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA, Richard Zhao
After START/RESTART, wait for busy bit to be set and
after STOP, wait for busy bit to be clear.
Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 4afba3e..156cc95 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -125,14 +125,19 @@ struct imx_i2c_struct {
/** Functions for IMX I2C adapter driver ***************************************
*******************************************************************************/
-static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
+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 */
- 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__);
@@ -144,6 +149,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx)
return -EIO;
}
schedule();
+ temp = readb(i2c_imx->base + IMX_I2C_I2SR);
}
return 0;
@@ -179,20 +185,32 @@ 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__);
/* 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)
+ 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)
+ 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)
@@ -202,16 +220,16 @@ 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);
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);
+
+ i2c_imx_bus_busy(i2c_imx, 0);
+
/* Disable I2C controller */
writeb(0, i2c_imx->base + IMX_I2C_I2CR);
}
@@ -344,7 +362,7 @@ 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,
@@ -370,14 +388,11 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
- /* Check if i2c bus is not busy */
- result = i2c_imx_bus_busy(i2c_imx);
+ /* Start I2C transfer */
+ result = i2c_imx_start(i2c_imx);
if (result)
goto fail0;
- /* Start I2C transfer */
- i2c_imx_start(i2c_imx);
-
/* read/write data */
for (i = 0; i < num; i++) {
if (i) {
@@ -386,6 +401,9 @@ 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)
+ goto fail0;
}
dev_dbg(&i2c_imx->adapter.dev,
"<%s> transfer message: %d\n", __func__, i);
--
1.6.0.4
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 2/4] i2c: imx: only imx1 needs disable delay
[not found] ` <1254290106-29272-1-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
@ 2009-09-30 5:55 ` Richard Zhao
[not found] ` <1254290106-29272-2-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
0 siblings, 1 reply; 12+ messages in thread
From: Richard Zhao @ 2009-09-30 5:55 UTC (permalink / raw)
To: kernel-bIcnvbaLZ9MEGnE8C9+IrQ
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA, Richard Zhao
check cpu_is_mx1() when set disable_delay.
Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 156cc95..c1e541c 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
/* Write divider value to register */
writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
- /*
- * 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);
+ 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
--
1.6.0.4
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 3/4] i2c: imx: add macros and printk to make debug easy
[not found] ` <1254290106-29272-2-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
@ 2009-09-30 5:55 ` Richard Zhao
[not found] ` <1254290106-29272-3-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
0 siblings, 1 reply; 12+ messages in thread
From: Richard Zhao @ 2009-09-30 5:55 UTC (permalink / raw)
To: kernel-bIcnvbaLZ9MEGnE8C9+IrQ
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA, Richard Zhao
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>
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
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 4/4] i2c: imx: disable clock when it's possible to save power.
[not found] ` <1254290106-29272-3-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
@ 2009-09-30 5:55 ` Richard Zhao
0 siblings, 0 replies; 12+ messages in thread
From: Richard Zhao @ 2009-09-30 5:55 UTC (permalink / raw)
To: kernel-bIcnvbaLZ9MEGnE8C9+IrQ
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA, Richard Zhao
Enable clock before START, disable it after STOP.
Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 87faea4..72ddea3 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -120,6 +120,7 @@ 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 ***************************************
@@ -210,6 +211,8 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
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);
@@ -254,6 +257,7 @@ static void i2c_imx_stop(struct imx_i2c_struct *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,
@@ -273,8 +277,8 @@ 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);
+ /* Store divider value */
+ i2c_imx->ifdr = i2c_clk_div[i][1];
if (cpu_is_mx1()) {
/*
@@ -555,7 +559,6 @@ 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);
/* Request IRQ */
ret = request_irq(i2c_imx->irq, i2c_imx_isr, 0, pdev->name, i2c_imx);
@@ -604,7 +607,6 @@ static int __init i2c_imx_probe(struct platform_device *pdev)
fail5:
free_irq(i2c_imx->irq, i2c_imx);
fail4:
- clk_disable(i2c_imx->clk);
clk_put(i2c_imx->clk);
fail3:
release_mem_region(i2c_imx->res->start, resource_size(res));
@@ -641,8 +643,6 @@ static int __exit i2c_imx_remove(struct platform_device *pdev)
if (pdata && pdata->exit)
pdata->exit(&pdev->dev);
- /* Disable I2C clock */
- clk_disable(i2c_imx->clk);
clk_put(i2c_imx->clk);
release_mem_region(i2c_imx->res->start, resource_size(i2c_imx->res));
--
1.6.0.4
^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay
2009-10-01 7:52 ` Richard Zhao
@ 2009-10-01 7:57 ` Sascha Hauer
-1 siblings, 0 replies; 12+ messages in thread
From: Sascha Hauer @ 2009-10-01 7:57 UTC (permalink / raw)
To: Richard Zhao
Cc: kernel-bIcnvbaLZ9MEGnE8C9+IrQ, linux-i2c-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
w.sang-bIcnvbaLZ9MEGnE8C9+IrQ
On Thu, Oct 01, 2009 at 03:52:15PM +0800, Richard Zhao wrote:
> On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> wrote:
> > On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
> >> check cpu_is_mx1() when set disable_delay.
> >>
> >> Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> >>
> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> >> index 156cc95..c1e541c 100644
> >> --- a/drivers/i2c/busses/i2c-imx.c
> >> +++ b/drivers/i2c/busses/i2c-imx.c
> >> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
> >> /* Write divider value to register */
> >> writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
> >>
> >> - /*
> >> - * 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);
> >> + 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);
> >> + }
> >
> > I think you should put the udelay(i2c_imx->disable_delay) in
> > cpu_is_mx1() rather than the calculation.
> >
> > 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 |
> >
> Do you think udelay(0) wast any more time than if()?
if (cpu_is_mx1()) is optimized out by the compiler.
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 |
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 2/4] i2c: imx: only imx1 needs disable delay
@ 2009-10-01 7:57 ` Sascha Hauer
0 siblings, 0 replies; 12+ messages in thread
From: Sascha Hauer @ 2009-10-01 7:57 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Oct 01, 2009 at 03:52:15PM +0800, Richard Zhao wrote:
> On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
> >> check cpu_is_mx1() when set disable_delay.
> >>
> >> Signed-off-by: Richard Zhao <linuxzsc@gmail.com>
> >>
> >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> >> index 156cc95..c1e541c 100644
> >> --- a/drivers/i2c/busses/i2c-imx.c
> >> +++ b/drivers/i2c/busses/i2c-imx.c
> >> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
> >> ? ? ? /* Write divider value to register */
> >> ? ? ? writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
> >>
> >> - ? ? /*
> >> - ? ? ?* 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);
> >> + ? ? 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);
> >> + ? ? }
> >
> > I think you should put the udelay(i2c_imx->disable_delay) in
> > cpu_is_mx1() rather than the calculation.
> >
> > 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 |
> >
> Do you think udelay(0) wast any more time than if()?
if (cpu_is_mx1()) is optimized out by the compiler.
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 |
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay
2009-10-01 7:26 ` Sascha Hauer
@ 2009-10-01 7:52 ` Richard Zhao
-1 siblings, 0 replies; 12+ messages in thread
From: Richard Zhao @ 2009-10-01 7:52 UTC (permalink / raw)
To: Sascha Hauer; +Cc: linux-arm-kernel, linux-i2c, kernel, w.sang
On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
>> check cpu_is_mx1() when set disable_delay.
>>
>> Signed-off-by: Richard Zhao <linuxzsc@gmail.com>
>>
>> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> index 156cc95..c1e541c 100644
>> --- a/drivers/i2c/busses/i2c-imx.c
>> +++ b/drivers/i2c/busses/i2c-imx.c
>> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
>> /* Write divider value to register */
>> writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>>
>> - /*
>> - * 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);
>> + 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);
>> + }
>
> I think you should put the udelay(i2c_imx->disable_delay) in
> cpu_is_mx1() rather than the calculation.
>
> 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 |
>
Do you think udelay(0) wast any more time than if()?
And Could I get all you comments in a single patch loop?
Thanks
Richard
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 2/4] i2c: imx: only imx1 needs disable delay
@ 2009-10-01 7:52 ` Richard Zhao
0 siblings, 0 replies; 12+ messages in thread
From: Richard Zhao @ 2009-10-01 7:52 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
>> check cpu_is_mx1() when set disable_delay.
>>
>> Signed-off-by: Richard Zhao <linuxzsc@gmail.com>
>>
>> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> index 156cc95..c1e541c 100644
>> --- a/drivers/i2c/busses/i2c-imx.c
>> +++ b/drivers/i2c/busses/i2c-imx.c
>> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
>> ? ? ? /* Write divider value to register */
>> ? ? ? writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>>
>> - ? ? /*
>> - ? ? ?* 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);
>> + ? ? 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);
>> + ? ? }
>
> I think you should put the udelay(i2c_imx->disable_delay) in
> cpu_is_mx1() rather than the calculation.
>
> 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 |
>
Do you think udelay(0) wast any more time than if()?
And Could I get all you comments in a single patch loop?
Thanks
Richard
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay
2009-10-01 1:13 ` Richard Zhao
@ 2009-10-01 7:26 ` Sascha Hauer
-1 siblings, 0 replies; 12+ messages in thread
From: Sascha Hauer @ 2009-10-01 7:26 UTC (permalink / raw)
To: Richard Zhao
Cc: kernel-bIcnvbaLZ9MEGnE8C9+IrQ, linux-i2c-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
w.sang-bIcnvbaLZ9MEGnE8C9+IrQ
On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
> check cpu_is_mx1() when set disable_delay.
>
> Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 156cc95..c1e541c 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
> /* Write divider value to register */
> writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>
> - /*
> - * 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);
> + 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);
> + }
I think you should put the udelay(i2c_imx->disable_delay) in
cpu_is_mx1() rather than the calculation.
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 |
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 2/4] i2c: imx: only imx1 needs disable delay
@ 2009-10-01 7:26 ` Sascha Hauer
0 siblings, 0 replies; 12+ messages in thread
From: Sascha Hauer @ 2009-10-01 7:26 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
> check cpu_is_mx1() when set disable_delay.
>
> Signed-off-by: Richard Zhao <linuxzsc@gmail.com>
>
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 156cc95..c1e541c 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
> /* Write divider value to register */
> writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>
> - /*
> - * 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);
> + 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);
> + }
I think you should put the udelay(i2c_imx->disable_delay) in
cpu_is_mx1() rather than the calculation.
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 |
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 2/4] i2c: imx: only imx1 needs disable delay
2009-10-01 1:13 [PATCH 1/4] i2c: imx: check busy bit when START/STOP Richard Zhao
@ 2009-10-01 1:13 ` Richard Zhao
0 siblings, 0 replies; 12+ messages in thread
From: Richard Zhao @ 2009-10-01 1:13 UTC (permalink / raw)
To: kernel-bIcnvbaLZ9MEGnE8C9+IrQ
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ, w.sang-bIcnvbaLZ9MEGnE8C9+IrQ,
Richard Zhao
check cpu_is_mx1() when set disable_delay.
Signed-off-by: Richard Zhao <linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 156cc95..c1e541c 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
/* Write divider value to register */
writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
- /*
- * 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);
+ 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
--
1.6.0.4
^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 2/4] i2c: imx: only imx1 needs disable delay
@ 2009-10-01 1:13 ` Richard Zhao
0 siblings, 0 replies; 12+ messages in thread
From: Richard Zhao @ 2009-10-01 1:13 UTC (permalink / raw)
To: linux-arm-kernel
check cpu_is_mx1() when set disable_delay.
Signed-off-by: Richard Zhao <linuxzsc@gmail.com>
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 156cc95..c1e541c 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
/* Write divider value to register */
writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
- /*
- * 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);
+ 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
--
1.6.0.4
^ permalink raw reply related [flat|nested] 12+ messages in thread
end of thread, other threads:[~2009-10-01 7:57 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-09-30 5:55 [PATCH 1/4] i2c: imx: check busy bit when START/STOP Richard Zhao
[not found] ` <1254290106-29272-1-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-09-30 5:55 ` [PATCH 2/4] i2c: imx: only imx1 needs disable delay Richard Zhao
[not found] ` <1254290106-29272-2-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-09-30 5:55 ` [PATCH 3/4] i2c: imx: add macros and printk to make debug easy Richard Zhao
[not found] ` <1254290106-29272-3-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-09-30 5:55 ` [PATCH 4/4] i2c: imx: disable clock when it's possible to save power Richard Zhao
2009-10-01 1:13 [PATCH 1/4] i2c: imx: check busy bit when START/STOP Richard Zhao
[not found] ` <1254359613-21210-1-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-10-01 1:13 ` [PATCH 2/4] i2c: imx: only imx1 needs disable delay Richard Zhao
2009-10-01 1:13 ` Richard Zhao
[not found] ` <1254359613-21210-2-git-send-email-linuxzsc-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2009-10-01 7:26 ` Sascha Hauer
2009-10-01 7:26 ` Sascha Hauer
2009-10-01 7:52 ` Richard Zhao
2009-10-01 7:52 ` Richard Zhao
[not found] ` <4e090d470910010052k37a0a4eep6d436e45e6524234-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2009-10-01 7:57 ` Sascha Hauer
2009-10-01 7:57 ` Sascha Hauer
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