Hi Johan,
On Sun, 24 Apr 2016 15:36:35 +0200
Johan Hovold <johan@xxxxxxxxxx> wrote:
> On Mon, Feb 29, 2016 at 04:11:20PM +0300, Maksim Salau wrote:
> > The adaptor can be found on development boards for 78k, RL78 and V850
> > microcontrollers produced by Renesas Electronics Corporation.
> >
> > This is not a full-featured USB to serial converter, however it allows
> > basic communication and simple control which is enough for programming of
> > on-board flash and debugging through a debug monitor.
> >
> > uPD78F0730 is a USB-enabled microcontroller with USB-to-UART conversion
> > implemented in firmware.
> >
> > This chip is also present in some debugging adaptors which use it for
> > USB-to-SPI conversion as well. The present driver doesn't cover SPI,
> > only USB-to-UART conversion is supported.
> >
> > Signed-off-by: Maksim Salau <maksim.salau@xxxxxxxxx>
> > ---
>
> Thanks for submitting this driver, and sorry for the late review. The
> code looks nice and clean, but I have some comments below.
>
Thank you for feedback.
> > +/* Control signal bits in UPD78F0730_CMD_SET_DTR_RTS command */
> > +#define UPD78F0730_RESET_RTS 0x01
> > +#define UPD78F0730_RESET_DTR 0x02
>
> Why are these named RESET? Looks like you use these bits to assert the
> signals when reading the datasheet.
>
Indeed, it turned out that RTS and DTR signals are inverted:
upd78f0730 has active-high levels, while others have active-low levels.
To match others I added inversion. May be it'll be a good idea to make
inversion optional by adding a module parameter.
> > + if (cflag & CRTSCTS) {
> > + dev_err(dev, "%s - hardware flow control is not supported\n",
> > + __func__);
>
> dev_warn and clear the setting in termios.
>
> Looks like the device does support it though?
There are means to enable it on protocol layer, but the CTS pin is not present.
I doubt if any flow control will ever be used with the adaptor.
I can add support for hardware flow control, but which flow control type should
prevail if both are enabled? Only one flow control type can be enabled at a time
according to the datasheet.
Also I'm not sure if software flow control will be useful in the adaptor itself
(due to small on-chip buffer size), software flow control implemented in a host
can be more effective.
Thanks,
Maksim.
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