[U-Boot] [PATCH] command "sspi": add write-only flag '.w' (discard read data)

[Mike Frysinger]

On Wednesday, July 20, 2011 13:04:47 Andreas Pretzsch wrote:
> I also thought about passing NULL for the read buffer, but a quick
> browse through the code showed that most, but not all SPI drivers are
> prepared for that. And as there is already a static rx buffer in the spi
> command code, I preferred to keep a few needless byte copies over fixing
> all the spi drivers...

those drivers are broken.  the SPI API requires them to handle NULL rx or tx 
buffers.  do not cater to broken code by avoiding fixing common code because 
of bugs in drivers.

> Following the common U-Boot way to do this, I'd suggest
> 	sspi [<bus>:]<cs>[.<mode>] <bit_len> <dout> [din_env_var]
> and either never print the read result to the console (my favorite) or
> only if no env variable to store is passed. To be defined, comments
> welcome.

is this the common u-boot approach ?  seems like extending every random func 
to take a supplementary env var is the wrong way.  if the hush shell simply 
supported syntax like:
	foo="`sspi ......`"
then every command would get this for free

> > along these lines, doesnt the general shell provide basic output
> > redirection to support "silencing" all commands rather than having to
> > add a "quiet" flag to them all ?  then your script could simply do
> > "sspi ... >/dev/null" (or however u-boot does it).
> 
> Not that I know of. Just tried on hush parser, no effect. Also looks
> like the whole redirect code is disabled by a #ifndef __U_BOOT__.
> Maybe one could change env stdout before and after, might work, but I'd
> call that grotesque...

yes, playing with stdout would be awful, but it would work today ;)
-mike
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 836 bytes
Desc: This is a digitally signed message part.
Url : http://lists.denx.de/pipermail/u-boot/attachments/20110720/6b17f8cb/attachment.pgp