[U-Boot] [PATCH V3 2/6] power: Explicitly select pmic device's bus

[Minkyu Kang]

Dear Leela Krishna Amudala,

On 12/11/13 19:04, Leela Krishna Amudala wrote:
> The current pmic i2c code assumes the current i2c bus is
> the same as the pmic device's bus. There is nothing ensuring
> that to be true. Therefore, select the proper bus before performing
> a transaction.
> 
> Signed-off-by: Aaron Durbin <adurbin at chromium.org>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> Signed-off-by: Leela Krishna Amudala <l.krishna at samsung.com>
> Reviewed-by: Doug Anderson <dianders at google.com>
> Acked-by: Simon Glass <sjg at chromium.org>
> ---
>  drivers/power/power_i2c.c |   62 +++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 57 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/power/power_i2c.c b/drivers/power/power_i2c.c
> index ac76870..3cafa4d 100644
> --- a/drivers/power/power_i2c.c
> +++ b/drivers/power/power_i2c.c
> @@ -16,9 +16,45 @@
>  #include <i2c.h>
>  #include <compiler.h>
>  
> +static int pmic_select(struct pmic *p)
> +{
> +	int ret, old_bus;

I think, old prefix is meaningless.
please fix it globally.

> +
> +	old_bus = i2c_get_bus_num();
> +	if (old_bus != p->bus) {

How about return immediately if get a bus.

if (old_bus == p->bus)
	return old_bus;

> +		debug("%s: Select bus %d\n", __func__, p->bus);
> +		ret = i2c_set_bus_num(p->bus);
> +		if (ret) {
> +			debug("%s: Cannot select pmic %s, err %d\n",
> +			      __func__, p->name, ret);
> +			return -1;
> +		}
> +	}
> +
> +	return old_bus;
> +}
> +
> +static int pmic_deselect(int old_bus)

in your patch, you never check a return value.
then is it void function or wrong usage?

And I think pmic_deselect function is almost same with pmic_select.
If you change the parameter for pmic_select to "int bus" then,
What is different with pmic_select?

for example.

bus = pmic_select(p->bus);
/* do something */
pmic_deselect(bus);

is same with.

bus = pmic_select(p->bus);
/* do something */
pmic_select(bus);

How do you think?

> +{
> +	int ret;
> +
> +	if (old_bus != i2c_get_bus_num()) {
> +		ret = i2c_set_bus_num(old_bus);
> +		debug("%s: Select bus %d\n", __func__, old_bus);
> +		if (ret) {
> +			debug("%s: Cannot restore i2c bus, err %d\n",
> +			      __func__, ret);
> +			return -1;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  int pmic_reg_write(struct pmic *p, u32 reg, u32 val)
>  {
>  	unsigned char buf[4] = { 0 };
> +	int ret, old_bus;
>  
>  	if (check_reg(p, reg))
>  		return -1;
> @@ -52,23 +88,33 @@ int pmic_reg_write(struct pmic *p, u32 reg, u32 val)
>  		return -1;
>  	}
>  
> -	if (i2c_write(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num))
> +	old_bus = pmic_select(p);
> +	if (old_bus < 0)
>  		return -1;
>  
> -	return 0;
> +	ret = i2c_write(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num);
> +	pmic_deselect(old_bus);

please add blank line.

> +	return ret;
>  }
>  
>  int pmic_reg_read(struct pmic *p, u32 reg, u32 *val)
>  {
>  	unsigned char buf[4] = { 0 };
>  	u32 ret_val = 0;
> +	int ret, old_bus;
>  
>  	if (check_reg(p, reg))
>  		return -1;
>  
> -	if (i2c_read(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num))
> +	old_bus = pmic_select(p);
> +	if (old_bus < 0)
>  		return -1;
>  
> +	ret = i2c_read(pmic_i2c_addr, reg, 1, buf, pmic_i2c_tx_num);
> +	pmic_deselect(old_bus);
> +	if (ret)
> +		return ret;
> +
>  	switch (pmic_i2c_tx_num) {
>  	case 3:
>  		if (p->sensor_byte_order == PMIC_SENSOR_BYTE_ORDER_BIG)
> @@ -98,9 +144,15 @@ int pmic_reg_read(struct pmic *p, u32 reg, u32 *val)
>  
>  int pmic_probe(struct pmic *p)
>  {
> -	i2c_set_bus_num(p->bus);
> +	int ret, old_bus;
> +
> +	old_bus = pmic_select(p);
> +	if (old_bus < 0)
> +		return -1;

please add blank line.

>  	debug("Bus: %d PMIC:%s probed!\n", p->bus, p->name);
> -	if (i2c_probe(pmic_i2c_addr)) {
> +	ret = i2c_probe(pmic_i2c_addr);
> +	pmic_deselect(old_bus);
> +	if (ret) {
>  		printf("Can't find PMIC:%s\n", p->name);
>  		return -1;
>  	}
> 

Thanks,
Minkyu Kang.