linux-kernel - Re: [PATCH] power:bq27xxx: 27000/10 read FLAGS register as single

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Date:	Tue, 26 Jul 2016 08:08:57 +0200
From:	"H. Nikolaus Schaller" <hns@...delico.com>
To:	"Andrew F . Davis" <afd@...com>,
	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Pali Rohár <pali.rohar@...il.com>,
	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	letux-kernel@...nphoenux.org
Subject: Re: [PATCH] power:bq27xxx: 27000/10 read FLAGS register as single

ping

> Am 18.07.2016 um 18:12 schrieb H. Nikolaus Schaller <hns@...delico.com>:
> 
> The bq27000 and bq27010 have a single byte FLAGS register.
> Other gauges have 16 bit FLAGS registers.
> 
> For reading the FLAGS register it is sufficient to read the single
> register instead of reading RSOC at the next higher address as
> well and then ignore the high byte.
> 
> This does not change functionality but optimizes i2c and hdq
> traffic.
> 
> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
> ---
> drivers/power/bq27xxx_battery.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/power/bq27xxx_battery.c b/drivers/power/bq27xxx_battery.c
> index 45f6ebf..56712b2 100644
> --- a/drivers/power/bq27xxx_battery.c
> +++ b/drivers/power/bq27xxx_battery.c
> @@ -656,8 +656,9 @@ static bool bq27xxx_battery_dead(struct bq27xxx_device_info *di, u16 flags)
> static int bq27xxx_battery_read_health(struct bq27xxx_device_info *di)
> {
> 	int flags;
> +	bool has_singe_flag = di->chip == BQ27000 || di->chip == BQ27010;
> 
> -	flags = bq27xxx_read(di, BQ27XXX_REG_FLAGS, false);
> +	flags = bq27xxx_read(di, BQ27XXX_REG_FLAGS, has_singe_flag);
> 	if (flags < 0) {
> 		dev_err(di->dev, "error reading flag register:%d\n", flags);
> 		return flags;
> @@ -760,7 +761,7 @@ static int bq27xxx_battery_current(struct bq27xxx_device_info *di,
> 	}
> 
> 	if (di->chip == BQ27000 || di->chip == BQ27010) {
> -		flags = bq27xxx_read(di, BQ27XXX_REG_FLAGS, false);
> +		flags = bq27xxx_read(di, BQ27XXX_REG_FLAGS, true);
> 		if (flags & BQ27000_FLAG_CHGS) {
> 			dev_dbg(di->dev, "negative current!\n");
> 			curr = -curr;
> -- 
> 2.7.3
>