Re: [PATCH v3 19/27] iio:pressure:mpl3115 Force alignment of buffer

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 23 Jul 2020 13:31:42 +0100
Jonathan Cameron <Jonathan.Cameron@Huawei.com> wrote:

> On Thu, 23 Jul 2020 15:17:16 +0300
> Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> 
> > On Wed, Jul 22, 2020 at 6:53 PM Jonathan Cameron <jic23@kernel.org> wrote:
> >   
> > > This one is unusual.  We have to do an explicit memset each time
> > > as we are reading 3 bytes into a potential 4 byte channel which
> > > may sometimes be a 2 byte channel depending on what is enabled.
> > > As such, moving the buffer to the heap in the iio_priv structure
> > > doesn't save us much.  We can't use a nice explicit structure
> > > on the stack either as the data channels have different storage
> > > sizes and are all separately controlled.    
> > 
> > I guess all non-standard cases (where no struct is applicable) deserve
> > for better comment in the code.
> >   
> 
> Sure can do that. I guess that will mean people actually think about
> it whilst copying examples form old into new drivers.
> 
> In many ways the no struct applicable is the 'standard' case. It's
> mere coincidence that in some drivers there are sufficiently few
> channels that the struct 'trick' works.  All the other channels
> are moving around even in those cases, it's just the timestamp
> that happens to only have one valid location.
> 
> I'll probably do a v4 at the weekend.
Well a weekend anyway :)
This one is sufficiently unusual I will bring it back for a v4 with
additional information in the comment.
> 
> Jonathan
> 
> 
>