[PATCH 6/7] ddr: altera: arria10: Change %i to %u for printf

[Tom Rini]

On Thu, Apr 16, 2020 at 03:11:45PM +0200, Marek Vasut wrote:
> On 4/16/20 2:55 PM, Tom Rini wrote:
> > On Wed, Apr 15, 2020 at 08:06:45PM +0200, Marek Vasut wrote:
> >> On 4/15/20 7:44 PM, Tom Rini wrote:
> >>> On Wed, Apr 15, 2020 at 05:16:52PM +0200, Marek Vasut wrote:
> >>>> On 4/15/20 5:14 PM, Tom Rini wrote:
> >>>>> On Wed, Apr 15, 2020 at 04:58:31PM +0200, Marek Vasut wrote:
> >>>>>> On 4/15/20 4:56 PM, Tom Rini wrote:
> >>>>>>> On Wed, Apr 15, 2020 at 02:45:08PM +0200, Marek Vasut wrote:
> >>>>>>>> On 4/15/20 11:00 AM, Ley Foon Tan wrote:
> >>>>>>>>> Tiny printf doesn't support %i, change to %u.
> >>>>>>>>>
> >>>>>>>>> Signed-off-by: Ley Foon Tan <ley.foon.tan at intel.com>
> >>>>>>>>> ---
> >>>>>>>>>  drivers/ddr/altera/sdram_arria10.c | 2 +-
> >>>>>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>>>>>>
> >>>>>>>>> diff --git a/drivers/ddr/altera/sdram_arria10.c b/drivers/ddr/altera/sdram_arria10.c
> >>>>>>>>> index e3f11984a978..8acf324117af 100644
> >>>>>>>>> --- a/drivers/ddr/altera/sdram_arria10.c
> >>>>>>>>> +++ b/drivers/ddr/altera/sdram_arria10.c
> >>>>>>>>> @@ -195,7 +195,7 @@ static void sdram_init_ecc_bits(u32 size)
> >>>>>>>>>  
> >>>>>>>>>  	dcache_enable();
> >>>>>>>>>  
> >>>>>>>>> -	printf("DDRCAL: Scrubbing ECC RAM (%i MiB).\n", size >> 20);
> >>>>>>>>> +	printf("DDRCAL: Scrubbing ECC RAM (%u MiB).\n", size >> 20);
> >>>>>>>>>  	memset((void *)0x8000, 0, size - 0x8000);
> >>>>>>>>>  	flush_dcache_all();
> >>>>>>>>>  	printf("DDRCAL: Scrubbing ECC RAM done.\n");
> >>>>>>>>
> >>>>>>>> Yes, sadly, tiny printf is broken so we need to patch code to work
> >>>>>>>> around that breakage.
> >>>>>>>
> >>>>>>> Yes, limited by design, thanks for changing.
> >>>>>>
> >>>>>> This code could be used without tiny printf, so this change is unnecessary.
> >>>>>
> >>>>> You've got it backwards.  Code that could be used by tiny printf needs
> >>>>> to use the more limited set of formats.  But this should have been using
> >>>>> %u all along?  %i is for int, %u is unsigned int.
> >>>>
> >>>> That would mean most of U-Boot needs to be limited to the subset of
> >>>> formatting characters supported by tiny printf, which is unrealistic.
> >>>
> >>> Not at all.  Only the code that's used in SPL and in tiny printf
> >>> situations needs to be limited to reduced set.  Which is why we're at
> >>> 4.5 years in and just now "oh, %i doesn't work?".
> >>
> >> I keep running into "oh, %i, such a basic C printf() feature, doesn't
> >> work" again and again, and it makes my work with U-Boot real annoying.
> >> This should be fixed in the printf implementation, not all over the code
> >> base. Also, it prevents sane code reuse, unless we start adding #ifdef
> >> TINY_PRINTF all over the place, which is just ew ...
> > 
> > I hear you saying "I type %i not %d without thinking about it", but I'm
> > telling you, think about it.
> 
> No, it works everywhere else just fine, except U-Boot SPL is special.

It works fine in SPL when we use the full printf, which is still a good
percent of the boards.

> This is a tiny-printf bug, period.

It's a feature of the explicitly reduced functionality printf.  It's the
whole point of the feature, provide as much output with as little code
as we can.

> 
> > I will not grow 200+ boards when there's
> > an easy way not to.
> 
> By ~6 bytes, which happens with almost every DM patch.
> I am not buying the size argument.

Nope, not true.  Boards with tiny printf rarely grow their SPL size from
general changes (SoC trees only get scrutiny over growth in platforms
outside their area) because I get this annoying about why they grow in
size.

-- 
Tom
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