Patchwork [U-Boot,04/24] mxc_i2c: clear i2sr before waiting for bit

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Submitter Troy Kisky
Date June 22, 2012, 4:11 a.m.
Message ID <1340338339-11626-4-git-send-email-troy.kisky@boundarydevices.com>
Download mbox | patch
Permalink /patch/166477/
State Superseded
Delegated to: Heiko Schocher
Headers show

Comments

Troy Kisky - June 22, 2012, 4:11 a.m.
Let's clear the sr register before waiting for
bit to be set, instead of clearing it after
hardware sets it. No real operational difference here,
but allows combining of i2c_imx_trx_complete and
i2c_imx_bus_busy in later patches.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
---
 drivers/i2c/mxc_i2c.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
Marek Vasut - June 22, 2012, 4:59 p.m.
Dear Troy Kisky,

> Let's clear the sr register before waiting for
> bit to be set, instead of clearing it after
> hardware sets it. No real operational difference here,
> but allows combining of i2c_imx_trx_complete and
> i2c_imx_bus_busy in later patches.
> 
> Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
> ---
>  drivers/i2c/mxc_i2c.c |    5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
> index 0fd508a..bae9335 100644
> --- a/drivers/i2c/mxc_i2c.c
> +++ b/drivers/i2c/mxc_i2c.c
> @@ -200,10 +200,8 @@ int i2c_imx_trx_complete(void)
>  	int timeout = I2C_MAX_TIMEOUT;
> 
>  	while (timeout--) {
> -		if (readb(&i2c_regs->i2sr) & I2SR_IIF) {
> -			writeb(0, &i2c_regs->i2sr);
> +		if (readb(&i2c_regs->i2sr) & I2SR_IIF)
>  			return 0;
> -		}
> 
>  		udelay(1);
>  	}
> @@ -215,6 +213,7 @@ static int tx_byte(struct mxc_i2c_regs *i2c_regs, u8
> byte) {
>  	unsigned ret;
> 
> +	writeb(0, &i2c_regs->i2sr);
>  	writeb(byte, &i2c_regs->i2dr);
>  	ret = i2c_imx_trx_complete();
>  	if (ret < 0)

If you could try this on mx51 and mx31, I'd be glad. I recall having some issues 
there.

If it works, add
Acked-by: Marek Vasut <marex@denx.de>

Best regards,
Marek Vasut
Troy Kisky - June 24, 2012, 12:18 a.m.
On 6/22/2012 9:59 AM, Marek Vasut wrote:
> Dear Troy Kisky,
>
>> Let's clear the sr register before waiting for
>> bit to be set, instead of clearing it after
>> hardware sets it. No real operational difference here,
>> but allows combining of i2c_imx_trx_complete and
>> i2c_imx_bus_busy in later patches.
>>
>> Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
>> ---
>>   drivers/i2c/mxc_i2c.c |    5 ++---
>>   1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
>> index 0fd508a..bae9335 100644
>> --- a/drivers/i2c/mxc_i2c.c
>> +++ b/drivers/i2c/mxc_i2c.c
>> @@ -200,10 +200,8 @@ int i2c_imx_trx_complete(void)
>>   	int timeout = I2C_MAX_TIMEOUT;
>>
>>   	while (timeout--) {
>> -		if (readb(&i2c_regs->i2sr) & I2SR_IIF) {
>> -			writeb(0, &i2c_regs->i2sr);
>> +		if (readb(&i2c_regs->i2sr) & I2SR_IIF)
>>   			return 0;
>> -		}
>>
>>   		udelay(1);
>>   	}
>> @@ -215,6 +213,7 @@ static int tx_byte(struct mxc_i2c_regs *i2c_regs, u8
>> byte) {
>>   	unsigned ret;
>>
>> +	writeb(0, &i2c_regs->i2sr);
>>   	writeb(byte, &i2c_regs->i2dr);
>>   	ret = i2c_imx_trx_complete();
>>   	if (ret < 0)
> If you could try this on mx51 and mx31, I'd be glad. I recall having some issues
> there.
>
> If it works, add
> Acked-by: Marek Vasut <marex@denx.de>
>
> Best regards,
> Marek Vasut
>
I can't try on a mx31, but will try on a mx51.

Thanks
Troy

Patch

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index 0fd508a..bae9335 100644
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -200,10 +200,8 @@  int i2c_imx_trx_complete(void)
 	int timeout = I2C_MAX_TIMEOUT;
 
 	while (timeout--) {
-		if (readb(&i2c_regs->i2sr) & I2SR_IIF) {
-			writeb(0, &i2c_regs->i2sr);
+		if (readb(&i2c_regs->i2sr) & I2SR_IIF)
 			return 0;
-		}
 
 		udelay(1);
 	}
@@ -215,6 +213,7 @@  static int tx_byte(struct mxc_i2c_regs *i2c_regs, u8 byte)
 {
 	unsigned ret;
 
+	writeb(0, &i2c_regs->i2sr);
 	writeb(byte, &i2c_regs->i2dr);
 	ret = i2c_imx_trx_complete();
 	if (ret < 0)