[U-Boot-Users] [PATCH] Support for csb535fs / i.MX21 LiteKit.

[Grant Likely]

On 2/28/07, Txema Lopez <tlopez at aotek.es> wrote:
> Grant Likely wrote:
>
> > On 2/27/07, Txema Lopez <tlopez at aotek.es> wrote:
> >
> >> Hi all,
> >> This patch, for the 1.2.0 version, adds support for the csb535fs board
> >> embedded in a csb935fs breakout board. The set is known as i.MX21
> >> Litekit.
> >
> >
> > With a quick perusal, the patch looks mostly okay.  Unfortunately,
> > it's inconvenient to review because it was sent as a gzipped
> > attachment instead of inline (I can't just hit 'reply' and start
> > typing comments).
> >
> I'm sorry, the patch size is more than the 40k U-Boot's limit, so ...

... it then makes sense to break it up into a couple of patches.  :-)
shorter patches are easier to review anyway.  Plus with smaller
patches, changes that get 'acked' aren't necessarily held up by
changes that need some more work.

>
> > Here are some general comments:
> > - You should add your copyright to all new files that you've added.
> > At the moment, your copyright only appears on a few of the new files.
>
> The cpu/arm926ejs/imx21 files have been copied from the cpu/arm920t/imx with
> a few modifications, so in the files  with minor changes I've left the
> old copyright.

Hmmm, indeed.  There are large sections of identical, or near
identical code between the two.  If I replace all the IMX21_* macros
with IMX_* in imx-regs.h, it results in a file that is somewhere
around 75% identical.

I know that slightly modified duplicate code is common in u-boot, so
this is not an critique on your work, but I'd really like to move away
from this mode of operation.  Duplicating the original file and
modifying it is certainly the easiest way to add support for a new
board/cpu, but I think it just leads to maintenance problems down the
roads.  For example, if one file has been duplicated with minor mods
10 times and a bug is found in it at a later date; the bug fix needs
to be applied to 10 files, not one.

Unfortunately, this situation is messy because the imx is in
cpu/arm920t and imx32 is in cpu/arm926ejs.  It probably requires the
creation of a new directory for the common imx soc bits, but where?
Perhaps under lib_arm/imx?

>
> > - Where did include/asm-arm/arch-imx21/imx21-regs.h come from?  There
> > is no copyright notice on it at all.
>
> It is a modification of include/asm-arm/arch-imx/imx-regs.h

ok

>
> > - There's a fair bit of inconsistent whitespace (intermixed space and
> > tab characters).
>
> Please, could you be more explicit and tell me where these mistakes are .

Configure your editor to make tab characters and trailing whitespace
visually distinct and you'll see them.

- lowlevel_init.S has a dozen or so lines indented with 4 spaces
instead of a tab character.  The coding standard is for indentation
with tab characters, and tab stops are at 8 character columns.
- imx21-regs.h: inconsistent throughout; but you probably inherited
this whitespace
- serial.c has a few lines where spaces precede tabs; pretty minor stuff.

>
> > - I do wonder at the amount of boilerplate required for each new board
> > port (but that's a longer ranged questions directed at the whole of
> > u-boot).
> >
> Me too.

:-)

-- 
Grant Likely, B.Sc. P.Eng.
Secret Lab Technologies Ltd.
grant.likely at secretlab.ca
(403) 399-0195