To be fair, using spidev to set up SPI and then bitbanging it from 
userspace is, at best, a very unorthodox approach.  It just happened to be 
suited to the particular problem that I trying to solve.  I can completely 
understand how such an approach would be viewed with some distaste by 
experienced kernel developers as it is far from the a standard approach to 
the problem.  And they really aren't wrong.  It isn't the correct way to 
develop a generalized solution.  I was just curious as to whether anyone 
else had attempted it and what their results were like.  

The particular project that required my SPI tinkering finished quite a 
while ago and it worked like a charm, so I'll just chalk it up as a 
learning experience and leave it at that.  The BBB, kernel code, etc. are 
all there for you to play around with.  Try crazy stuff out and have fun 
with it.  Some will work out OK and some won't, but you won't know until 
you give it a shot.

On Thursday, October 9, 2014 2:54:05 PM UTC-4, William Hermans wrote:
>
> *Well, I have gotten it working before using mmap() calls because I had a 
>> very specific need for it for a proprietary project that I can't share the 
>> code for, but I was informed (in no uncertain terms) that using mmap() for 
>> SPI comms in user space is a bad idea and that I am not a smart person:*
>>
>
> Isnt it funny how when you *may* ask these people who responded to you 
> post they would not offer any assistance. But as soon as you put up working 
> code for something that works for you, Suddenly everyone is offering their 
> "help"
>
> Personally, I can see several flaws with using mmap in any situation. But 
> if it works for you, and works well. I say to hell with what anyone else 
> says. So long as it's abstracted, and no one else has to maintain it.
>
> I keep seeing the same text from the same person "how very unlinix like of 
> you" or some such garbage. Sorry, I can not disagree more. First of all, 
> mmap was created for a reason. This reason has nothing to do with critiques 
> on user implementation while using it. Secondly, Linux is about freedom, 
> not one individuals "dictatorship" or misconception of what Linux should be.
>
> Also, I've seen some implementations many of the commentators of the post 
> you linked to and . . . yeah let us just say that some of the stuff I have 
> seen is far from perfect. So many of them do not have a leg to stand on 
> when it comes to criticizing someone else's implementation.
>
> Andrew, anyway you're probably smart enough to not need my encouragement, 
> but I'd encourage you to keep using mmap, while thinking of alternate 
> methods of achieving the same end goal. While again thinking which method 
> might be better and why. Software development is great for constantly 
> keeping our minds busy while learning new techniques, and technologies. 
> There is always something new to learn, and no one amongst us started off 
> by knowing *everything*.
>

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