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From: Lars-Peter Clausen <lars@metafoo.de>
To: Grazvydas Ignotas <notasas@gmail.com>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>,
	Rodolfo Giometti <giometti@linux.it>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/14] bq27x00: Cache battery registers
Date: Sun, 13 Feb 2011 19:56:25 +0100	[thread overview]
Message-ID: <4D582959.9010505@metafoo.de> (raw)
In-Reply-To: <AANLkTiks6Dy8az8qxNJm4UPzJSRSmFU0b+M6ipjSey3f@mail.gmail.com>

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On 02/13/2011 04:14 PM, Grazvydas Ignotas wrote:
> On Sat, Feb 12, 2011 at 9:39 PM, Lars-Peter Clausen <lars@metafoo.de> wrote:
>> This patch adds a register cache to the bq27x00 battery driver.
>> Usually multiple, if not all, power_supply properties are queried at once,
>> for example when an uevent is generated. Since some registers are used by
>> multiple properties caching the registers should reduce the number of
>> reads.
>>
>> The cache is valid for 5 seconds this roughly matches the internal update
>> interval of the current register for the bq27000/bq27200.
>>
>> Fast changing properties(*_NOW) which can be obtained by reading a single
>> register are not cached.
>>
>> It will also be used in the follow up patch to check if the battery status
>> has been changed since the last update to emit power_supply_changed events.
>>
>> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
>> ---
>>  drivers/power/bq27x00_battery.c |  272 +++++++++++++++++++++-----------------
>>  1 files changed, 150 insertions(+), 122 deletions(-)
>>
>> diff --git a/drivers/power/bq27x00_battery.c b/drivers/power/bq27x00_battery.c
>> index 44bc76b..0c94693 100644
>> --- a/drivers/power/bq27x00_battery.c
>> +++ b/drivers/power/bq27x00_battery.c
>> @@ -19,7 +19,6 @@
> 
> <snip>
> 
>> +static void bq27x00_update(struct bq27x00_device_info *di)
>> +{
>> +       struct bq27x00_reg_cache cache = {0, };
>> +       bool is_bq27500 = di->chip == BQ27500;
>> +
>> +       cache.flags = bq27x00_read(di, BQ27x00_REG_FLAGS, is_bq27500);
>> +       if (cache.flags >= 0) {
>> +               cache.capacity = bq27x00_battery_read_rsoc(di);
>> +               cache.temperature = bq27x00_read(di, BQ27x00_REG_TEMP, false);
>> +               cache.time_to_empty = bq27x00_battery_read_time(di, BQ27x00_REG_TTE);
>> +               cache.time_to_empty_avg = bq27x00_battery_read_time(di, BQ27x00_REG_TTECP);
>> +               cache.time_to_full = bq27x00_battery_read_time(di, BQ27x00_REG_TTF);
>> +
>> +               if (!is_bq27500)
>> +                       cache.current_now = bq27x00_read(di, BQ27x00_REG_AI, false);
>>        }
>>
> 
> <snip>
> 
>> -static int bq27x00_battery_current(struct bq27x00_device_info *di)
>> +static int bq27x00_battery_current(struct bq27x00_device_info *di,
>> +       union power_supply_propval *val)
>>  {
>> -       int ret;
>> -       int curr = 0;
>> -       int flags = 0;
>> +       int curr;
>>
>> -       ret = bq27x00_read(di, BQ27x00_REG_AI, &curr, false);
>> -       if (ret) {
>> -               dev_err(di->dev, "error reading current\n");
>> -               return 0;
>> -       }
>> +       if (di->chip == BQ27000)
>> +           curr = bq27x00_read(di, BQ27x00_REG_AI, false);
>> +       else
>> +           curr = di->cache.current_now;
> 
> You're updating current_now in cache if it's not bq27500, but
> bypassing cache for bq27000?

Right, that should of course be ' == BQ27500'

> 
> Why do you still want to cache the current while you are no longer
> caching voltage, because it needs 2 register reads I guess?

Yes. I've given it some though and I would rather avoid the chance of returning
bogus values, because the AI register is already updated, but flags still
contains the old state.

- - Lars
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  reply	other threads:[~2011-02-13 18:56 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-12 19:38 [PATCH v2 00/14] POWER: BQ27x00: New Properties, fixes, bq27000 support Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 01/14] bq27x00: Add type property Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 02/14] bq27x00: Improve temperature property precession Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 03/14] bq27x00: Fix CURRENT_NOW property Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 04/14] bq27x00: Return -ENODEV for properties if the battery is not present Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 05/14] bq27x00: Prepare code for addition of bq27000 platform driver Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 06/14] bq27x00: Add bq27000 support Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 07/14] bq27x00: Cache battery registers Lars-Peter Clausen
2011-02-13 15:14   ` Grazvydas Ignotas
2011-02-13 18:56     ` Lars-Peter Clausen [this message]
2011-02-14  3:01   ` [PATCH 07/14 v3] " Lars-Peter Clausen
2011-02-14 21:58     ` Grazvydas Ignotas
2011-02-14 22:14       ` Lars-Peter Clausen
2011-02-15 11:48         ` Grazvydas Ignotas
2011-02-15 22:39           ` Grazvydas Ignotas
2011-02-21  8:28             ` Lars-Peter Clausen
2011-02-21 14:00               ` Grazvydas Ignotas
2011-02-21 14:49                 ` Lars-Peter Clausen
2011-02-21 21:23                   ` Grazvydas Ignotas
2011-02-12 19:39 ` [PATCH v2 07/14] bq27X00: " Lars-Peter Clausen
2011-02-12 19:52   ` Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 08/14] bq27x00: Poll battery state Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 09/14] bq27x00: Add new properties Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 10/14] bq27x00: Add MODULE_DEVICE_TABLE Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 11/14] bq27x00: Give more specific reports on battery status Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 12/14] bq27x00: Minor cleanups Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 13/14] bq27x00: Cleanup bq27x00_i2c_read Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 14/14] Ignore -ENODATA errors when generating a uevent Lars-Peter Clausen

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