On Mon, 21 Jan 2019 at 09:39, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:
>
> Hi Krzysztof,
>
> On 2019-01-19 21:17, Krzysztof Kozlowski wrote:
> > On Fri, Jan 18, 2019 at 02:27:54PM +0100, Marek Szyprowski wrote:
> >> s3c_rtc_enable/disable_clk() functions were designed to be called multiple
> >> times without reference counting, because they were initially used in
> > s/used/used only/
> > (if I understand correctly the logic)
> >
> >> alarm setting/clearing functions, which can be called both when alarm is
> >> already set or not. Later however, calls to those functions have been added to
> >> other places in the driver - like time and /proc reading callbacks, what
> >> results in broken alarm if any of such events happens after the alarm has
> >> been set. Fix this by simplifying s3c_rtc_enable/disable_clk() functions
> >> to rely on proper reference counting in clock core and move alarm enable
> >> counter to s3c_rtc_setaie() function.
> >>
> >> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> >> ---
> >> drivers/rtc/rtc-s3c.c | 67 ++++++++++++++++++-------------------------
> >> 1 file changed, 28 insertions(+), 39 deletions(-)
> >>
> >> diff --git a/drivers/rtc/rtc-s3c.c b/drivers/rtc/rtc-s3c.c
> >> index 04c68178c42d..e682977b4f6e 100644
> >> --- a/drivers/rtc/rtc-s3c.c
> >> +++ b/drivers/rtc/rtc-s3c.c
> >> @@ -39,7 +39,7 @@ struct s3c_rtc {
> >> void __iomem *base;
> >> struct clk *rtc_clk;
> >> struct clk *rtc_src_clk;
> >> - bool clk_disabled;
> >> + bool alarm_enabled;
> >>
> >> const struct s3c_rtc_data *data;
> >>
> >> @@ -47,7 +47,7 @@ struct s3c_rtc {
> >> int irq_tick;
> >>
> >> spinlock_t pie_lock;
> >> - spinlock_t alarm_clk_lock;
> >> + spinlock_t alarm_lock;
> > Maybe add short comment that it protects only "alarm_enabled" property?
> >
> >>
> >> int ticnt_save;
> >> int ticnt_en_save;
> >> @@ -70,44 +70,28 @@ struct s3c_rtc_data {
> >>
> >> static int s3c_rtc_enable_clk(struct s3c_rtc *info)
> >> {
> >> - unsigned long irq_flags;
> >> int ret = 0;
> >>
> >> - spin_lock_irqsave(&info->alarm_clk_lock, irq_flags);
> >> + ret = clk_enable(info->rtc_clk);
> >> + if (ret)
> >> + goto out;
> > The out label is now empty so just "return ret". It is easier to read -
> > no need to jump anywhere to see the simple return.
> >
> >>
> >> - if (info->clk_disabled) {
> >> - ret = clk_enable(info->rtc_clk);
> >> - if (ret)
> >> + if (info->data->needs_src_clk) {
> >> + ret = clk_enable(info->rtc_src_clk);
> >> + if (ret) {
> >> + clk_disable(info->rtc_clk);
> >> goto out;
> >> -
> >> - if (info->data->needs_src_clk) {
> >> - ret = clk_enable(info->rtc_src_clk);
> >> - if (ret) {
> >> - clk_disable(info->rtc_clk);
> >> - goto out;
> >> - }
> >> }
> >> - info->clk_disabled = false;
> >> }
> >> -
> >> out:
> >> - spin_unlock_irqrestore(&info->alarm_clk_lock, irq_flags);
> >> -
> >> return ret;
> >> }
> >>
> >> static void s3c_rtc_disable_clk(struct s3c_rtc *info)
> >> {
> >> - unsigned long irq_flags;
> >> -
> >> - spin_lock_irqsave(&info->alarm_clk_lock, irq_flags);
> >> - if (!info->clk_disabled) {
> >> - if (info->data->needs_src_clk)
> >> - clk_disable(info->rtc_src_clk);
> >> - clk_disable(info->rtc_clk);
> >> - info->clk_disabled = true;
> >> - }
> >> - spin_unlock_irqrestore(&info->alarm_clk_lock, irq_flags);
> >> + if (info->data->needs_src_clk)
> >> + clk_disable(info->rtc_src_clk);
> >> + clk_disable(info->rtc_clk);
> >> }
> >>
> >> /* IRQ Handlers */
> >> @@ -135,6 +119,7 @@ static irqreturn_t s3c_rtc_alarmirq(int irq, void *id)
> >> static int s3c_rtc_setaie(struct device *dev, unsigned int enabled)
> >> {
> >> struct s3c_rtc *info = dev_get_drvdata(dev);
> >> + unsigned long flags;
> >> unsigned int tmp;
> >> int ret;
> >>
> >> @@ -151,17 +136,19 @@ static int s3c_rtc_setaie(struct device *dev, unsigned int enabled)
> >>
> >> writeb(tmp, info->base + S3C2410_RTCALM);
> >>
> >> - s3c_rtc_disable_clk(info);
> >> + spin_lock_irqsave(&info->alarm_lock, flags);
> >>
> >> - if (enabled) {
> >> - ret = s3c_rtc_enable_clk(info);
> >> - if (ret)
> >> - return ret;
> >> - } else {
> >> + if (info->alarm_enabled && !enabled)
> >> s3c_rtc_disable_clk(info);
> >> - }
> >> + else if (!info->alarm_enabled && enabled)
> >> + ret = s3c_rtc_enable_clk(info);
> >>
> >> - return 0;
> >> + info->alarm_enabled = enabled;
> >> + spin_unlock_irqrestore(&info->alarm_lock, flags);
> >> +
> >> + s3c_rtc_disable_clk(info);
> >> +
> >> + return ret;
> >> }
> >>
> >> /* Set RTC frequency */
> >> @@ -357,10 +344,10 @@ static int s3c_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
> >>
> >> writeb(alrm_en, info->base + S3C2410_RTCALM);
> >>
> >> - s3c_rtc_disable_clk(info);
> >> -
> >> s3c_rtc_setaie(dev, alrm->enabled);
> >>
> >> + s3c_rtc_disable_clk(info);
> > I do not understand this change - why do you have to move the disable
> > clk? The s3c_rtc_setaie() takes care about clock enabling/disabling for
> > the time of accessing registers.
>
> This was micro optimization, s3c_rtc_setaie() increases clock enable
> count, so by changing the call order we can avoid one disable/enable
> sequence.
OK.
> >> +
> >> return 0;
> >> }
> >>
> >> @@ -491,7 +478,7 @@ static int s3c_rtc_probe(struct platform_device *pdev)
> >> return -EINVAL;
> >> }
> >> spin_lock_init(&info->pie_lock);
> >> - spin_lock_init(&info->alarm_clk_lock);
> >> + spin_lock_init(&info->alarm_lock);
> >>
> >> platform_set_drvdata(pdev, info);
> >>
> >> @@ -591,6 +578,8 @@ static int s3c_rtc_probe(struct platform_device *pdev)
> >>
> >> s3c_rtc_setfreq(info, 1);
> >>
> >> + s3c_rtc_disable_clk(info);
> > I cannot find the reason why this is related to this particular change.
> > I mean, it looks reasonable because previously the clock looked like it
> > was enabled all the time... but maybe this should be separate pach?
>
> It wasn't enabled all the time, because the call to s3c_rtc_setfreq()
> disabled it (remember there was no clock enable reference counting!).
> Now once we have enable/disable reference counting, we need to keep them
> balanced.
I get it, thanks!
Best regards,
Krzysztof
