spigen problem

[Emmanuel Vadot]

On Mon, 29 Apr 2019 11:34:34 -0600
Ian Lepore <ian at freebsd.org> wrote:

> On Tue, 2019-04-30 at 02:18 +0900, Mori Hiroki wrote:
> > Hi
> > 
> > I add small spi lcd on RT3050. This lcd controller is S6D0151.
> > 
> > S6D0151 transfer is tree byte command then tree byte data.
> > 
> > I use spigen mruby rapper. This rapper use SPIGENIOC_TRANSFER.
> > 
> > I try to send tree byte command. But spi transfer is six byte.
> > 
> > This is reason.
> > 
> > sys/dev/spibus/spigen.c
> > 
> >         error = copyin(st->st_command.iov_base, transfer.tx_cmd,
> >            transfer.tx_cmd_sz = transfer.rx_cmd_sz = st-
> > >st_command.iov_len);  
> > 
> > 
> > This lcd not work six byte transfer.
> > 
> > How do I fix this ?
> > 
> > Regards
> > 
> > Hiroki Mori
> > 
> 
> I'm not sure what you mean by "This is the reason", that code sets up
> the transfer for exactly as many bytes as you requested in
> st_command.iov_len.  If you set that to three bytes, only three bytes
> will be transfered.
> 
> -- Ian

 I guess that Mori-San wants to transfer 3 bytes but receive 6, if it's
that you need to set tx_cmd_sz with dummy bytes count too. The tx
buffer will also need to contain the dummy bytes values.

-- 
Emmanuel Vadot <manu at bidouilliste.com> <manu at freebsd.org>