Re: [PATCH v5 12/13] spi: mxic: Use spi_mem_generic_supports_op()

[Miquel Raynal <miquel.raynal@bootlin.com>]

miquel.raynal@bootlin.com wrote on Thu, 16 Dec 2021 10:01:47 +0100:

> Hi Mark,
> 
> broonie@kernel.org wrote on Wed, 15 Dec 2021 19:19:11 +0000:
> 
> > On Wed, Dec 15, 2021 at 08:05:48PM +0100, Boris Brezillon wrote:
> >   
> > > There's also a second option that doesn't involve patching existing
> > > users: add a spi_mem_controller_caps to the spi_controller struct, and
> > > check this instance in your spi_mem_default_supports_op()
> > > implementation. Note that the buswidth check done in the generic
> > > helper is already based on caps exposed by the controller
> > > through spi_controller.mode_bits ({RX/TX}_{DUAL,QUAD,OCTAL} bits).    
> > 
> > This approach is quite nice for things like this - having things as data
> > rather than code.  The only issue is if any of the caps end up varying
> > by operation and we need different capabilities but that doesn't look
> > too likely here I think?  
> 
> Indeed that was the main point of the original review from Boris, the
> capabilities should be fixed on the controller's lifetime. So I believe
> we are safe.
> 
> I think I am going to propose the following:
> 	const struct spi_controller_mem_ops *mem_ops;
> +	struct spi_controller_mem_caps mem_caps;
> 
> As the structure is not supposed to enlarge dramatically in the near
> future, I guess it's fine to have it defined statically. Please tell me
> if you prefer a *mem_caps pointer.

Actually as the spi-mem.h header is not included in spi.h, it makes
defining a static mem_caps entry harder. I'll go for another approach.
Maybe putting the capabilities within the spi_controller_mem_ops
structure, as these are highly related.

> I'll send a proposal soon.
> 
> Thanks,
> Miquèl


Thanks,
Miquèl