linux-kernel - Re: [PATCH 02/03] clocksource: em

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Message-ID: <CANqRtoS24CUp3cpoWykJ5Ty5XT3Yn+LNvGL_kF5NdEPAQL0f4A@mail.gmail.com>
Date:	Fri, 25 May 2012 12:39:06 +0900
From:	Magnus Damm <magnus.damm@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, arnd@...db.de, horms@...ge.net.au,
	linux-sh@...r.kernel.org, johnstul@...ibm.com, rjw@...k.pl,
	lethal@...ux-sh.org, gregkh@...uxfoundation.org, olof@...om.net
Subject: Re: [PATCH 02/03] clocksource: em_sti: Emma Mobile STI driver V2

Hi Thomas,

On Fri, May 25, 2012 at 8:42 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Wed, 9 May 2012, Magnus Damm wrote:
>> +static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
>> +{
>> +     struct em_sti_priv *p = dev_id;
>> +
>> +     /* Always regprogram timer compare A */
>> +     if (p->ced.mode == CLOCK_EVT_MODE_PERIODIC)
>> +             em_sti_update(p);
>
> Why do you want to do that? The core code already handles timers which
> only support oneshot mode.

Oh, I wasn't aware that oneshot only is a valid combination. Thanks
for pointing that out, the code will surely become cleaner!

>> +     spin_lock_irqsave(&p->lock, flags);
>
> Please make that a raw_spinlock.

Ok!

>> +static void em_sti_clock_event_mode(enum clock_event_mode mode,
>> +                                 struct clock_event_device *ced)
>> +{
>> +     struct em_sti_priv *p = ced_to_em_sti(ced);
>> +
>> +     /* deal with old setting first */
>> +     switch (ced->mode) {
>> +     case CLOCK_EVT_MODE_PERIODIC:
>> +     case CLOCK_EVT_MODE_ONESHOT:
>> +             em_sti_stop(p, USER_CLOCKEVENT);
>> +             break;
>> +     default:
>> +             break;
>> +     }
>> +
>> +     switch (mode) {
>> +     case CLOCK_EVT_MODE_PERIODIC:
>> +             dev_info(&p->pdev->dev, "used for periodic clock events\n");
>> +             em_sti_start(p, USER_CLOCKEVENT);
>> +             clockevents_config(&p->ced, p->rate);
>> +             p->delta = (p->rate + HZ/2) / HZ;
>> +             p->next = em_sti_count(p);
>> +             em_sti_update(p);
>> +             break;
>
> All that code in this case can go away.

Right!

>> +static void em_sti_register_clockevent(struct em_sti_priv *p)
>> +{
>> +     struct clock_event_device *ced = &p->ced;
>> +
>> +     memset(ced, 0, sizeof(*ced));
>> +     ced->name = dev_name(&p->pdev->dev);
>> +     ced->features = CLOCK_EVT_FEAT_PERIODIC;
>> +     ced->features |= CLOCK_EVT_FEAT_ONESHOT;
>
> If you make that:
>
>        ced->features = CLOCK_EVT_FEAT_ONESHOT;

Gotcha!

Thanks,

/ magnus
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