[PATCH] tiny-printf: Support %i

[Simon Glass]

Hi Marek,

On Tue, 14 Apr 2020 at 07:41, Marek Vasut <marex at denx.de> wrote:
>
> On 4/14/20 3:26 PM, Tom Rini wrote:
> > On Tue, Apr 14, 2020 at 02:24:18PM +0200, Marek Vasut wrote:
> >> On 4/14/20 5:03 AM, Tom Rini wrote:
> >>> On Tue, Apr 14, 2020 at 03:17:16AM +0200, Marek Vasut wrote:
> >>>> On 4/14/20 1:27 AM, Tom Rini wrote:
> >>>>> On Fri, Apr 10, 2020 at 08:54:49PM +0200, Marek Vasut wrote:
> >>>>>
> >>>>>> The most basic printf("%i", value) formating string was missing,
> >>>>>> add it for the sake of convenience.
> >>>>>>
> >>>>>> Signed-off-by: Marek Vasut <marex at denx.de>
> >>>>>> Cc: Simon Glass <sjg at chromium.org>
> >>>>>> Cc: Stefan Roese <sr at denx.de>
> >>>>>> ---
> >>>>>>  lib/tiny-printf.c | 3 ++-
> >>>>>>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>>>>>
> >>>>>> diff --git a/lib/tiny-printf.c b/lib/tiny-printf.c
> >>>>>> index 1138c7012a..8fc7e48d99 100644
> >>>>>> --- a/lib/tiny-printf.c
> >>>>>> +++ b/lib/tiny-printf.c
> >>>>>> @@ -242,6 +242,7 @@ static int _vprintf(struct printf_info *info, const char *fmt, va_list va)
> >>>>>>                                  goto abort;
> >>>>>>                          case 'u':
> >>>>>>                          case 'd':
> >>>>>> +                        case 'i':
> >>>>>>                                  div = 1000000000;
> >>>>>>                                  if (islong) {
> >>>>>>                                          num = va_arg(va, unsigned long);
> >>>>>> @@ -251,7 +252,7 @@ static int _vprintf(struct printf_info *info, const char *fmt, va_list va)
> >>>>>>                                          num = va_arg(va, unsigned int);
> >>>>>>                                  }
> >>>>>>
> >>>>>> -                                if (ch == 'd') {
> >>>>>> +                                if (ch != 'u') {
> >>>>>>                                          if (islong && (long)num < 0) {
> >>>>>>                                                  num = -(long)num;
> >>>>>>                                                  out(info, '-');
> >>>>>
> >>>>> How much does the size change and where do we see this as a problem?
> >>>>
> >>>> Any code which uses %i in SPL just misbehaves, e.g.
> >>>> printf("%s[%i] value=%x", __func__, __LINE__, val);
> >>>> prints function name and then incorrect value, because %i is ignored.
> >>>> This is also documented in the commit message.
> >>>>
> >>>> U-Boot grows in size massively due to all the DM/DT bloat which is being
> >>>> forced upon everyone, but there the uncontrolled growth is apparently OK
> >>>> even if it brings no obvious improvement, rather the opposite. And yet
> >>>> here, size increase suddenly matters? Sorry, that's not right.
> >>>>
> >>>> The code grows by 6 bytes.
> >>>
> >>> Yes, it matters for _tiny-printf_ as that's where we have little to no
> >>> room for growth.
> >>
> >> How many systems that use tiny-printf in SPL are also forced to use DM
> >> in SPL ?
> >
> > I don't know how many times I've said no one is forced to switch to DM
> > in SPL.
>
> This is beside the point, there are boards which use SPL and DM, because
> the non-DM drivers are steadily going away. So the growth in SPL size is
> there, either directly or as a side-effect.

I think this is a good point. For serial we have a debug UART. I am
think it would be useful to have a 'simple bypass' for more
subsystems. For example, for I2C we could have a simple option to
access a single I2C driver directly, bypassing driver model. Of course
this is painful to do before we have completed I2C migration.

[..]

Regards,
Simon