Re: [PATCH V1] spi: Add support for Double Transfer Rate (DTR) mode

[Mukesh Kumar Savaliya]

Thanks Tudor !

On 3/26/2025 8:18 PM, Tudor Ambarus wrote:
> On 3/26/25 2:25 PM, Mukesh Kumar Savaliya wrote:
> > Hi Mark, thanks for your comment.
> >
> > On 3/26/2025 6:34 PM, Mark Brown wrote:
> > > On Wed, Mar 26, 2025 at 02:09:54PM +0530, Mukesh Kumar Savaliya wrote:
> > >
> > > > This change introduces a new field `dtr_mode` in the `spi_transfer`
> > > > structure. The `dtr_mode` field allows protocol drivers to indicate if
> > > > Double Transfer Rate (DTR) mode is supported for a given transfer. When
> > > > `dtr_mode` is set to true, the SPI controller will use DTR mode
> > > > otherwise, it will default to single transfer mode.
> > >
> > > > The QSPI controller driver uses this flag and configures single or
> > > > double
> > > > transfer rate using the controller register.
> > >
> > > We should have a flag in the controller indicating if it supports this,
> > > and code in the core which returns an error if a driver attempts to use
> > > it when the controller doesn't support it.
> > Have added below in spi.h which can be set by client and controller
> > driver should be using it to decide mode.
> >
> > + bool        dtr_mode;
> >
> > since default it's false, should continue with SDR.
> > I believe for QSPI, it supports SDR or DDR, but it's not applicable to
> > standard SPI right ? So not sure in which case we should return an error ?
>
> Please check how spimem is dealing with DTR, same ideas shall be applied
> for spi transfers.
Yes, i just got it. Have kept my proposal aligning to this. Looks 
similar to spi_mem_controller_is_capable(). Please review reply to Mark 
if that is matching expectations OR have more suggestion/corrections.
> Cheers,
> ta