[PATCH v2 03/15] ARM: mxs: Add reset routines

[Shawn Guo]

Hi Uwe,

2010/11/30 Uwe Kleine-König <u.kleine-koenig at pengutronix.de>:
> Hello,
>
> On Mon, Nov 29, 2010 at 07:59:13PM +0800, Shawn Guo wrote:
>> +/*
>> + * Reset the system. It is called by machine_restart().
>> + */
>> +void arch_reset(char mode, const char *cmd)
>> +{
>> +     /* Set wdog count */
>> +     __raw_writel(1, wdog_base + MXS_RTC_WATCHDOG);
> Which unit is used here?  Does the timer only start running when it's
> enabled below?  Does this apply when the watchdog is already in use,
> too?
>
The unit RTC (i.MX28 RM chapter 22) which has watchdog function inside
is used here.

Good catch here.  I thought the watchdog counter only starts counting
after WATCHDOG_EN is set.  But I just confirmed it with designer that
the watchdog counter starts counting once CLKGATE is cleared, and
WATCHDOG_EN bit only controls the watchdog reset generation.  Even in
this case, 1ms should be long enough for the WATCHDOG_EN setting below
to get executed before counter goes to 0.  What is your concern here?

I should change mdelay(500) to mdelay(1).

>> +
>> +     /* Assert SRS signal */
>> +     __raw_writel(MXS_WATCHDOG_EN, wdog_base + MXS_SET_ADDR);
>> +
>> +     /* Wait for reset to assert... */
>> +     mdelay(500);
>> +
>> +     pr_err("Watchdog reset failed to assert reset\n");
>> +
>> +     /* Delay to allow the serial port to show the message */
>> +     mdelay(50);
>> +
>> +     /* We'll take a jump through zero as a poor second */
>> +     cpu_reset(0);
>> +}
>> +
>> +void mxs_arch_reset_init(void __iomem *base)
>> +{
>> +     struct clk *clk;
>> +
>> +     wdog_base = base;
>> +
>> +     clk = clk_get_sys("rtc", NULL);
>> +     if (!IS_ERR(clk))
>> +             clk_enable(clk);
> Actually I'm not sure if it's worth to do this.  It might hurt if you
> want to save power.
>
> I'll try to find a time slot to look into that.
>
As this is the very initial support, I would not consider the power
saving very much.  I will be very happy to applied your solution after
it becomes available.

-- 
Regards,
Shawn