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SubjectRe: [PATCH v7 3/5] RTC: RK808: add RTC driver for RK808
From
Hi,

On Tue, Sep 2, 2014 at 8:52 PM, Doug Anderson <dianders@chromium.org> wrote:
> Chris,
>
> On Tue, Sep 2, 2014 at 7:01 PM, Chris Zhong <zyw@rock-chips.com> wrote:
>>
>> On 09/02/2014 11:58 AM, Doug Anderson wrote:
>>>>
>>>> +static int rk808_rtc_probe(struct platform_device *pdev)
>>>> >+{
>>>> >+ struct rk808 *rk808 = dev_get_drvdata(pdev->dev.parent);
>>>> >+ struct rk808_rtc *rk808_rtc;
>>>> >+ struct rtc_time tm;
>>>> >+ int ret;
>>>> >+
>>>> >+ rk808_rtc = devm_kzalloc(&pdev->dev, sizeof(*rk808_rtc),
>>>> > GFP_KERNEL);
>>>> >+ if (rk808_rtc == NULL)
>>>> >+ return -ENOMEM;
>>>> >+
>>>> >+ platform_set_drvdata(pdev, rk808_rtc);
>>>> >+ rk808_rtc->rk808 = rk808;
>>>> >+
>>>> >+ /* start rtc running by default, and use shadowed timer. */
>>>> >+ ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
>>>> >+ BIT_RTC_CTRL_REG_STOP_RTC_M |
>>>> >+ BIT_RTC_CTRL_REG_RTC_READSEL_M,
>>>> >+ BIT_RTC_CTRL_REG_RTC_READSEL_M);
>>>
>>> I think this should still be setting to 0, not to
>>> BIT_RTC_CTRL_REG_RTC_READSEL_M. Otherwise the first read of the time
>>> will return that time that was frozen at probe time, right? AKA: if
>>> probe happens at 11:00:00 and then we read the time at 11:00:05 we'll
>>> still read 11:00:00 the first time.
>>>
>> Sorry, I did not describe correctly, in the previous mail.
>> Actually, RK808 has a "GET_TIME" switch bit. When "GET_TIME" bit rising
>> thansiton to 1,
>> the current time will save in a shadowed register.
>> If "READSEL" = 1, read rtc time register, return the frozen time.
>> If we need the real time, clr this "READSEL" bit.
>
> Ohhhhh! I see. I clearly didn't look closely enough at the whole
> register description in the user manual. I think you've got it right,
> then.
>
> I think this would be more obvious if you added a comment and you set
> both the high and low bits at the same time. AKA:
>
> + /* Force an update of the shadowed registers right now */
> + ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
> + BIT_RTC_CTRL_REG_RTC_GET_TIME,
> + BIT_RTC_CTRL_REG_RTC_GET_TIME);
> + if (ret) {
> + dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
> + return ret;
> + }
> +
> + ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG,
> + BIT_RTC_CTRL_REG_RTC_GET_TIME,
> + BIT_RTC_CTRL_REG_RTC_GET_TIME);

Doh, this one was supposed to be setting it back to 0.


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