qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH] i.MX: Improve EPIT timer code.


From: Peter Chubb
Subject: Re: [Qemu-devel] [PATCH] i.MX: Improve EPIT timer code.
Date: Tue, 28 May 2013 09:36:22 +1000
User-agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (Goj┼Ź) APEL/10.8 Emacs/23.4 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO)

Hi Jean,
   Thanks for this.  Most of it appears cosmetic and an improvement.
   Comments in-line below.

>  
>  /*
>   * Update interrupt status
>   */
> -static void imx_timerp_update(IMXTimerPState *s)
> +static void imx_timer_epit_update(IMXTimerEPITState *s)
>  {
> -    if (s->sr && (s->cr & CR_OCIEN)) {
> +    if (s->sr && (s->cr & CR_OCIEN) && (s->cr & CR_EN)) {

Why not
       if (s->sr && (s->cr & (CR_OCIEN|CR_EN) == (CR_OCIEN|CR_EN)))

>          qemu_irq_raise(s->irq);
>      } else {
>          qemu_irq_lower(s->irq);
>      }
>  }
>  
> -static void set_timerp_freq(IMXTimerPState *s)
> +static void imx_timer_epit_set_freq(IMXTimerEPITState *s)
>  {
>      unsigned clksrc;
>      unsigned prescaler;
> -    uint32_t freq;

getting rid of this variable means a pointer dereference every time
below.  That's OK at some optimisation levels and for some compilers
as they'll cache the variable.  But I prefer making this explicit so
less competent compilers can avoid the pointer dereference.

>  
>      clksrc = extract32(s->cr, CR_CLKSRC_SHIFT, 2);
>      prescaler = 1 + extract32(s->cr, CR_PRESCALE_SHIFT, 12);
>  
> -    freq = imx_clock_frequency(s->ccm, imx_timerp_clocks[clksrc]) / 
> prescaler;
> +    s->freq = imx_clock_frequency(s->ccm,
> +                                  imx_timer_epit_clocks[clksrc]) / prescaler;
>  
> -    s->freq = freq;
>      DPRINTF("Setting ptimer frequency to %u\n", freq);

And here it's inconsistent --- s/freq/s->freq/ and as you've renamed,
maybe s/ptimer/epit/

The rest looks OK.

I'm not that keen on the longer names, though.
Maybe s/timer_epit/epit/  throughout.

--
Dr Peter Chubb                                  peter.chubb AT nicta.com.au
http://www.ssrg.nicta.com.au          Software Systems Research Group/NICTA



reply via email to

[Prev in Thread] Current Thread [Next in Thread]