On 26/05/2021 19:35:31+0800, qxj511mail@gmail.com wrote:
quoted
If the time on the RTC is invalid, then rtc_valid_tm has to fail, there
is nothing to fix here.
I mean, if you try to get the time or execute hwclock command, Invalid arguments are returned when the RTC chip is not initialized
therefore，we need to get a valid time
Well, the time is invalid so hwclock needs to know it is invalid.
Returning a bogus time and date doesn't make it right. hwclock needs to
fail.
qxj511mail@gmail.com
From: Alexandre Belloni
Date: 2021-05-26 05:18
To: <redacted>
CC: Nobuhiro Iwamatsu; a.zummo; linux-rtc; linux-kernel; 邱晓金
Subject: Re: Re: [PATCH] rtc: rs5c372: Fix read the time from RTC is illegal When reading time from an uninitialized RTC chip, The value may be illegal
Hi,
On 25/05/2021 19:24:14+0800, qxj511mail@gmail.com wrote:
quoted
Please briefly describe the patch contained in the email to the subject.
And, please write a description of the patch in the text
----> The legal days are 1 to 31 and the legal month is less than or equal to 12.
But for an uninitialized RTC chip, the time is random.
Days and month may be zero, leading to RTC_valid_TM failed
If the time on the RTC is invalid, then rtc_valid_tm has to fail, there
is nothing to fix here.
quoted
add description && fix build error, so I modefied my code :
Signed-off-by: qiuxiaojin <redacted>
---
drivers/rtc/rtc-rs5c372.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
index 3bd6eaa0dcf6..cb3f90983778 100644
--- a/drivers/rtc/rtc-rs5c372.c
+++ b/drivers/rtc/rtc-rs5c372.c
@@ -128,6 +128,9 @@ struct rs5c372 {
char *regs;
};
+
+static int rs5c372_rtc_set_time(struct device *dev, struct rtc_time *tm);
+
static int rs5c_get_regs(struct rs5c372 *rs5c)
{
struct i2c_client *client = rs5c->client;@@ -212,6 +215,7 @@ static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
struct rs5c372 *rs5c = i2c_get_clientdata(client);
int status = rs5c_get_regs(rs5c);
unsigned char ctrl2 = rs5c->regs[RS5C_REG_CTRL2];
+ int flags_utime = 0;
if (status < 0)
return status;
@@ -239,12 +243,28 @@ static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
tm->tm_wday = bcd2bin(rs5c->regs[RS5C372_REG_WDAY] & 0x07);
tm->tm_mday = bcd2bin(rs5c->regs[RS5C372_REG_DAY] & 0x3f);
+ /* The value read from the register may be zero, which is an illegal value */
+ if (tm->tm_mday < 1) {
+ flags_utime++;
+ tm->tm_mday = 1;
+ }
+
/* tm->tm_mon is zero-based */
tm->tm_mon = bcd2bin(rs5c->regs[RS5C372_REG_MONTH] & 0x1f) - 1;
+ if (tm->tm_mon < 0) {
+ /* avoid illegal month */
+ flags_utime++;
+ tm->tm_mon = 0;
+ }
+
/* year is 1900 + tm->tm_year */
tm->tm_year = bcd2bin(rs5c->regs[RS5C372_REG_YEAR]) + 100;
+ /* update legal time */
+ if (flags_utime > 0)
+ rs5c372_rtc_set_time(dev, tm);
+
dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
"mday=%d, mon=%d, year=%d, wday=%d\n",
__func__,--
2.29.0
qxj511mail@gmail.com
From: Nobuhiro Iwamatsu
Date: 2021-05-24 12:40
To: qxj511mail
CC: Alessandro Zummo; Alexandre Belloni; linux-rtc; Linux Kernel Mailing List; qiuxiaojin
Subject: Re: [PATCH] rtc: rs5c372: Fix read the time from RTC is illegal When reading time from an uninitialized RTC chip, The value may be illegal
Hi,
2021年5月20日(木) 12:32 <qxj511mail@gmail.com>:
>
> From: qiuxiaojin <qiuxiaojin@cvte.com>
Please briefly describe the patch contained in the email to the subject.
And, please write a description of the patch in the text
>
> Signed-off-by: qiuxiaojin <qiuxiaojin@cvte.com>
> ---
> drivers/rtc/rtc-rs5c372.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
> index 3bd6eaa0dcf6..ce61e15d5f3a 100644
> --- a/drivers/rtc/rtc-rs5c372.c
> +++ b/drivers/rtc/rtc-rs5c372.c
> @@ -212,6 +212,7 @@ static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
> struct rs5c372 *rs5c = i2c_get_clientdata(client);
> int status = rs5c_get_regs(rs5c);
> unsigned char ctrl2 = rs5c->regs[RS5C_REG_CTRL2];
> + int flags_utime = 0;
>
> if (status < 0)
> return status;
> @@ -239,12 +240,27 @@ static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
> tm->tm_wday = bcd2bin(rs5c->regs[RS5C372_REG_WDAY] & 0x07);
> tm->tm_mday = bcd2bin(rs5c->regs[RS5C372_REG_DAY] & 0x3f);
>
> + if (tm->tm_mday < 1) {
> + // The value read from the register may be zero, which is an illegal value
Please use C89 style commet (/* */).
> + flags_utime = flags_utime + 1;
I like using ++ (flags_utime++).
> + tm->tm_mday = 1;
> + }
> +
> /* tm->tm_mon is zero-based */
> tm->tm_mon = bcd2bin(rs5c->regs[RS5C372_REG_MONTH] & 0x1f) - 1;
>
> + if (tm->tm_mon < 0) {
> + flags_utime = flags_utime + 1;
> + tm->tm_mday = 0;
> + }
> +
> /* year is 1900 + tm->tm_year */
> tm->tm_year = bcd2bin(rs5c->regs[RS5C372_REG_YEAR]) + 100;
>
> + if (flags_utime > 0) {
{} is unnecessary.
> + rs5c372_rtc_set_time(dev, tm);
A build error will occur because there is no declaration of
rs5c372_rtc_set_time.
Please make sure this can be compiled.
> + }
> +
> dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
> "mday=%d, mon=%d, year=%d, wday=%d\n",
> __func__,
> --
> 2.29.0
>
--
Nobuhiro Iwamatsu
iwamatsu at {nigauri.org / debian.org}
GPG ID: 40AD1FA6
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com