From: Doug Anderson <dianders@chromium.org>
To: Chris Zhong <zyw@rock-chips.com>
Cc: "Rob Herring" <robh+dt@kernel.org>,
"Pawel Moll" <pawel.moll@arm.com>,
"Mark Rutland" <mark.rutland@arm.com>,
"Ian Campbell" <ijc+devicetree@hellion.org.uk>,
"Kumar Gala" <galak@codeaurora.org>,
"Samuel Ortiz" <sameo@linux.intel.com>,
"Lee Jones" <lee.jones@linaro.org>,
"Liam Girdwood" <lgirdwood@gmail.com>,
"Alessandro Zummo" <a.zummo@towertech.it>,
"Mike Turquette" <mturquette@linaro.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
rtc-linux@googlegroups.com,
"Grant Likely" <grant.likely@linaro.org>,
"Lin Huang" <hl@rock-chips.com>,
"Tao Huang" <huangtao@rock-chips.com>,
"Eddie Cai" <cf@rock-chips.com>,
zhangqing <zhangqing@rock-chips.com>, xxx <xxx@rock-chips.com>,
"Heiko Stübner" <heiko@sntech.de>,
"Olof Johansson" <olof@lixom.net>,
"Sonny Rao" <sonnyrao@chromium.org>,
"Dmitry Torokhov" <dtor@chromium.org>,
"Javier Martinez Canillas" <javier.martinez@collabora.co.uk>,
"Kever Yang" <kever.yang@rock-chips.com>
Subject: Re: [PATCH v7 3/5] RTC: RK808: add RTC driver for RK808
Date: Tue, 2 Sep 2014 20:52:17 -0700 [thread overview]
Message-ID: <CAD=FV=Xq+EaSX=wqkpRVKg5e5Rf-CMWD8ZBJ_-SZqoo-KrX0LA@mail.gmail.com> (raw)
In-Reply-To: <54067674.3040007@rock-chips.com>
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);
+ if (ret) {
+ dev_err(dev, "Failed to update bits rtc_ctrl: %d\n", ret);
+ return ret;
+ }
...doing them both at the same time makes it obvious that this is a
one-time copy triggered by the "rising edge" of this bit. It also
means you don't need any "goto" for error handling.
-Doug
next prev parent reply other threads:[~2014-09-03 3:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-01 9:07 [PATCH v7 0/5] Add rockchip RK808 pmic driver Chris Zhong
2014-09-01 9:07 ` [PATCH v7 1/5] dt-bindings: Add RK808 device tree bindings document Chris Zhong
2014-09-02 3:42 ` Doug Anderson
2014-09-02 3:42 ` Doug Anderson
2014-09-02 3:46 ` Doug Anderson
2014-09-01 9:39 ` [PATCH v7 2/5] MFD: RK808: Add new mfd driver for RK808 Chris Zhong
2014-09-01 10:09 ` Lee Jones
2014-09-01 21:35 ` Doug Anderson
2014-09-02 7:24 ` Lee Jones
2014-09-01 9:43 ` [PATCH v7 3/5] RTC: RK808: add RTC " Chris Zhong
2014-09-02 3:58 ` Doug Anderson
2014-09-03 2:01 ` Chris Zhong
2014-09-03 3:52 ` Doug Anderson [this message]
2014-09-03 3:53 ` Doug Anderson
2014-09-01 9:46 ` [PATCH v7 4/5] clk: RK808: Add clkout " Chris Zhong
2014-09-01 21:55 ` Mike Turquette
2014-09-01 9:47 ` [PATCH v7 5/5] regulator: RK808: Remove pdata from the regulator Chris Zhong
2014-09-02 4:20 ` Doug Anderson
2014-09-02 19:40 ` [PATCH v7 0/5] Add rockchip RK808 pmic driver Heiko Stübner
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