Re: [PATCH] iio: Fix the sorting functionality in iio_gts_build_avail_time_table

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 20 Mar 2024 09:02:46 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> Hi Jonathan, all.
> 
> I am resending this as I don't think I found the mail from lore. I wrote 
> this using my phone so maybe it was sent as HTML and stuck to some 
> filters. If you receive this twice - I am sorry...
> 
> la 16. maalisk. 2024 klo 15.40 Jonathan Cameron <jic23@kernel.org 
> <mailto:jic23@kernel.org>> kirjoitti:
> 
>  > On Fri, 15 Mar 2024 15:49:10 -0500
>  > Chenyuan Yang <chenyuan0y@gmail.com <mailto:chenyuan0y@gmail.com>>
>  > wrote:
>  >  
>  > > Hi Matti,
>  > >
>  > > Thanks for your reply!
>  > >  
>  > > > I think the suggested-by tag is a bit of an overkill :) I don't feel
>  > > > like taking the credit - you spotted the problem and fixed it!  
>  > >
>  > > You did help me figure out the real issue here and how to fix it :)
>  > >  
>  > > > Do you think you could fix the removal of the duplicates too?  
>  > >
>  > > Sure, I can help to implement the deduplication logic.
>  > > Here is a potential patch for it based on your help.
>  > > Besides, I changed the stop condition in the inner loop to `j < idx`
>  > > since the current last index should be `idx - 1`.  
>  >
>  > Matti, I didn't follow why duplicates are a problem?  
> 
> The function here builds the tables for available integration times. 
> These are shown to users via sysfs (if I'm not mistaken) - and while the 
> user-space algorithms may tolerate dublicates, they are ugly (in my 
> opinon) when available times are manually listed.
> 
> 
>  > Sure the code is less efficient, but do we end up with a wrong
>  > answer as a result (I've not checked logic, but I'd expect either
>  > first or last of repeating values to be used depending on the alg).  
> 
> If we discuss completely omitting duplicated times from the driver 
> (which was one thing I referred in my previous mail) - then we are 
> likely to face problems as there can be register values, which then 
> can't be translated to times, read from a HW.
> 
> Eg, we need to have everything described in driver tables used for 
> driver's computations - but (in my opinion) we should drop duplicates 
> from these tables which we hand over via sysfs.
> 
All makes sense. Thanks for the explanation.

J
> Yours,
> -- Matti