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.
>> +
>> 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.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
