Messages in this thread | | | Date | Sun, 27 Sep 2015 22:04:34 -0500 | From | Josh Cartwright <> | Subject | Re: [PATCH] rtc: Add a driver for Micro Crystal RV8803 |
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Hello Alexandre-
Few comments below.
On Sat, Sep 26, 2015 at 03:54:39PM +0200, Alexandre Belloni wrote: > This driver supports the following functions: > - reading and settings time > - alarms when connected to an IRQ > - reading and clearing the voltage low flags > - nvram > > Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> > --- [..] > +static irqreturn_t rv8803_handle_irq(int irq, void *dev_id) > +{ > + struct i2c_client *client = dev_id; > + struct rv8803_data *rv8803 = i2c_get_clientdata(client); > + unsigned long events = 0; > + u8 flags; > + > + flags = i2c_smbus_read_byte_data(client, RV8803_FLAG); > + if (flags <= 0) > + return IRQ_HANDLED;
Returning IRQ_HANDLED when no interrupt condition is met. That seems like a bad idea.
> + if (flags & RV8803_FLAG_V1F) > + dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n"); > + > + if (flags & RV8803_FLAG_V2F) > + dev_warn(&client->dev, "Voltage low, data loss detected.\n"); > + > + if (flags & RV8803_FLAG_TF) { > + flags &= ~RV8803_FLAG_TF; > + rv8803->ctrl &= ~RV8803_CTRL_TIE; > + events |= RTC_PF; > + } > + > + if (flags & RV8803_FLAG_AF) { > + flags &= ~RV8803_FLAG_AF; > + rv8803->ctrl &= ~RV8803_CTRL_AIE; > + events |= RTC_AF; > + } > + > + if (flags & RV8803_FLAG_UF) { > + flags &= ~RV8803_FLAG_UF; > + rv8803->ctrl &= ~RV8803_CTRL_UIE; > + events |= RTC_UF; > + } > + > + if (events) { > + rtc_update_irq(rv8803->rtc, 1, events); > + i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
How are the many read-modify-write cycles for flags safe without any form of synchronization? (Especially given the interrupt handler isn't under ops_lock).
> + i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL, > + rv8803->ctrl); > + } > + > + return IRQ_HANDLED; > +} > + [..] > +static int rv8803_get_alarm(struct device *dev, struct rtc_wkalrm *alrm) > +{ > + struct rv8803_data *rv8803 = dev_get_drvdata(dev); > + struct i2c_client *client = rv8803->client; > + u8 alarmvals[3]; > + int flags, ret; > + > + if (client->irq <= 0) > + return -EINVAL;
It'd be cleaner just to have a second set of rtc_class_ops that can be switched between based on whether a valid interrupt is specified.
Josh
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