On Mon, Nov 23, 2020 at 12:10:54AM +0100, Alexandre Belloni wrote:

Hi,

On 22/11/2020 23:27:37+0100, Jonathan Neuschäfer wrote:

quoted

With this driver, mainline Linux can keep its time and date in sync with
the vendor kernel.

Advanced functionality like alarm and automatic power-on is not yet
supported.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>

Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

However, two comments below:

quoted

+static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct ntxec_rtc *rtc = dev_get_drvdata(dev);
+	int res = 0;
+
+	/*
+	 * To avoid time overflows while we're writing the full date/time,
+	 * set the seconds field to zero before doing anything else. For the
+	 * next 59 seconds (plus however long it takes until the RTC's next
+	 * update of the second field), the seconds field will not overflow
+	 * into the other fields.
+	 */
+	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(0));
+	if (res)
+		return res;
+
+	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100));
+	if (res)
+		return res;
+
+	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1));
+	if (res)
+		return res;
+
+	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday));
+	if (res)
+		return res;
+
+	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour));
+	if (res)
+		return res;
+
+	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min));
+	if (res)
+		return res;
+
+	return regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec));

Couldn't you do a regmap_block_write or a regmap_multi_reg_write which
would be more efficient as they would be locking the regmap only once.

I can't find regmap_block_write anywhere, but regmap_multi_reg_write
looks like a good approach to simplify the code here.


[...]

Note that this won't compile after
https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git/commit/?id=fdcfd854333be5b30377dc5daa9cd0fa1643a979

We can solve that with immutable branches though.

Thanks for the heads-up. Please let me know if/when there is any action
that I need to take here.


Jonathan