Re: [PATCH 09/12] iio: dac: ad5686: implement new sync() op for the spi bus

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Wed, Jun 03, 2026 at 01:55:25PM +0100, Jonathan Cameron wrote:
> On Wed, 3 Jun 2026 13:26:43 +0100
> Rodrigo Alencar <455.rodrigo.alencar@gmail.com> wrote:
> > On 26/06/02 10:14PM, Andy Shevchenko wrote:
> > > On Tue, Jun 02, 2026 at 05:33:56PM +0100, Rodrigo Alencar via B4 Relay wrote:
> > >   
> > > > Use of local SPI bus data to manage a collection of SPI transfers and
> > > > flush them to the SPI platform driver with the sync() operation. This
> > > > allows for faster handling of multiple channel DAC writes, avoiding kernel
> > > > overhead per spi_sync() call, which will be helpful when enabling
> > > > triggered buffer support.  
> > > 
> > > Why spi_message_alloc() can't be used instead of manual handling?
> > > (Seems no current users, so you even can modify it for your needs.)  
> > 
> > I need to manually call spi_message_add_tail() to append messages.
> > I suppose that such function is a bit weird and no wonder why it
> > is not being used. struct spi_message_with_transfers might need
> > to be properly declared so that users can populate the transfer
> > array without manually moving pointers or having to redefine the type.
> >  
> Agreed it would be significant surgery. Perhaps worth it as a follow up
> if you can find a couple of drivers open coding the equivalent.
> 
> Otherwise perhaps send a patch removing spi_message_alloc()

My experience with removing of dead code in SPI is that Mark is reluctant
doing that. Maybe if somebody tries that  it will work this time.

-- 
With Best Regards,
Andy Shevchenko