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Message-ID: <6e54ebbf-fad4-46bc-8b5a-e92acdb6b643@seco.com>
Date: Fri, 21 Jun 2024 11:23:58 -0400
From: Sean Anderson <sean.anderson@...o.com>
To: Alessandro Zummo <a.zummo@...ertech.it>,
Alexandre Belloni <alexandre.belloni@...tlin.com>, linux-rtc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Subject: Re: [PATCH v3] rtc: abx80x: Don't warn about oscillator failure after
PoR
On 1/25/24 12:14, Sean Anderson wrote:
> On 1/8/24 17:05, Sean Anderson wrote:
>> On 12/11/23 11:03, Sean Anderson wrote:
>>> On 10/19/23 12:39, Sean Anderson wrote:
>>>> According to the datasheet, the "oscillator failure" bit is set
>>>>
>>>>> ...on a power on reset, when both the system and battery voltages have
>>>>> dropped below acceptable levels. It is also set if an Oscillator Failure
>>>>> occurs....
>>>>
>>>> From testing, this bit is also set if a software reset is initiated.
>>>>
>>>> This bit has a confusing name; it really tells us whether the time data
>>>> is valid. We clear it when writing the time. If it is still set, that
>>>> means there is a persistent issue (such as an oscillator failure),
>>>> instead of a transient one (such as power loss).
>>>>
>>>> Because there are several other reasons which might cause this bit
>>>> to be set (including booting for the first time or a battery failure),
>>>> do not warn about oscillator failures willy-nilly. This may cause system
>>>> integrators to waste time looking into the wrong line of investigation.
>>>>
>>>> We continue printing a message about invalid time data or an oscillator
>>>> failure. There is no voltimeter in this RTC, so this is the best
>>>> indication that the battery is dead (or dying) and reeds replacement.
>>>>
>>>> Signed-off-by: Sean Anderson <sean.anderson@...o.com>
>>>> ---
>>>> Note that the following drivers all warn when they detect a problem with
>>>> the oscillator:
>>>>
>>>> drivers/rtc/rtc-ds1672.c
>>>> drivers/rtc/rtc-pcf*.c
>>>> drivers/rtc/rtc-rs5c*.c
>>>> drivers/rtc/rtc-sc27xx.c
>>>>
>>>> So warning about such an error has good precedent.
>>>>
>>>> Changes in v3:
>>>> - Use info since this is a good indication of a battery failure
>>>>
>>>> Changes in v2:
>>>> - Use debug instead of info in the typical case (no battery)
>>>>
>>>> drivers/rtc/rtc-abx80x.c | 17 ++++++++++++++++-
>>>> 1 file changed, 16 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
>>>> index fde2b8054c2e..f463a58a240b 100644
>>>> --- a/drivers/rtc/rtc-abx80x.c
>>>> +++ b/drivers/rtc/rtc-abx80x.c
>>>> @@ -127,6 +127,7 @@ struct abx80x_priv {
>>>> struct rtc_device *rtc;
>>>> struct i2c_client *client;
>>>> struct watchdog_device wdog;
>>>> + bool wrote_time;
>>>> };
>>>>
>>>> static int abx80x_write_config_key(struct i2c_client *client, u8 key)
>>>> @@ -179,6 +180,7 @@ static int abx80x_enable_trickle_charger(struct i2c_client *client,
>>>> static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
>>>> {
>>>> struct i2c_client *client = to_i2c_client(dev);
>>>> + struct abx80x_priv *priv = i2c_get_clientdata(client);
>>>> unsigned char buf[8];
>>>> int err, flags, rc_mode = 0;
>>>>
>>>> @@ -193,7 +195,18 @@ static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
>>>> return flags;
>>>>
>>>> if (flags & ABX8XX_OSS_OF) {
>>>> - dev_err(dev, "Oscillator failure, data is invalid.\n");
>>>> + /*
>>>> + * The OF bit can be set either because of a reset
>>>> + * (PoR/Software reset) or because of an oscillator
>>>> + * failure. Effectively, it indicates that the stored
>>>> + * time is invalid. When we write the time, we clear
>>>> + * this bit. If it stays set, then this indicates an
>>>> + * oscillator failure.
>>>> + */
>>>> + if (priv->wrote_time)
>>>> + dev_err(dev, "Oscillator failure\n");
>>>> + else
>>>> + dev_info(dev, "Time data invalid\n");
>>>> return -EINVAL;
>>>> }
>>>> }
>>>> @@ -219,6 +232,7 @@ static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
>>>> static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
>>>> {
>>>> struct i2c_client *client = to_i2c_client(dev);
>>>> + struct abx80x_priv *priv = i2c_get_clientdata(client);
>>>> unsigned char buf[8];
>>>> int err, flags;
>>>>
>>>> @@ -252,6 +266,7 @@ static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
>>>> dev_err(&client->dev, "Unable to write oscillator status register\n");
>>>> return err;
>>>> }
>>>> + priv->wrote_time = true;
>>>>
>>>> return 0;
>>>> }
>>>
>>> ping?
>>
>> ping again?
>
> Does anyone read this list? This patch has gone unreviewed since December of 2022!
>
> --Sean
ping again
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