[U-Boot-Users] [PATCH/review] Blackfin: use on-chip syscontrol() to reset

[Detlev Zundel]

Hi Mike,

> On Sunday 01 June 2008, Wolfgang Denk wrote:
>> In message <1212298724-15152-10-git-send-email-vapier at gentoo.org> you wrote:
>> > When available, use the on-chip syscontrol() rom function to perform a
>> > system reset rather than our own local method.
>> ...
>> > -		asm("jump (%0);" : : "a" (bfin_reset));
>> > +		if (0 /*BOOTROM_CAPS_SYSCONTROL -- current silicon is broken*/)
>> > +			syscontrol(SYSCTRL_SOFTRESET, NULL, NULL);
>> > +		else
>> > +			asm("jump (%0);" : : "a" (bfin_reset));
>> >  }
>>
>> Your comment suggests you change something, but actually you;re just
>> adding dead code.
>
> it's dead code because the current silicon is broken.  i know the code works 
> as ive tested it in scenarios where the anomaly isnt triggered, it just cant 
> be enabled until fixed hardware is released.  it's much easier to go back and 
> fix 1 if statement then have to carry this patch somewhere it can got lost 
> and i need to waste time and rewrite it.

Hm.  If the current - available - silicon is broken, then even if it is
fixed in the future, you will have to support both versions, right?  So
in the end you will need to have a discriminating factor on what to use.

So if you introduced some variable or bit in a variable (a define
doesn't look promising as I guess you want to support both broken and
non-broken silicon with a single image), you could have correct code now
and in the future - and no dead code complaints.

PowerPC Linux btw. does quite a lot of such "cpu_feature" stuff to
dynamically accomodate lots of different silicon.

Cheers
  Detlev

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