linux-kernel - Re: [PATCH] USB: serial: ftdi_sio: only bind FT232H if UART mode is enabled

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Date:   Tue, 25 Jul 2017 13:43:54 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Anatolij Gustschin <agust@...x.de>
Cc:     Johan Hovold <johan@...nel.org>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] USB: serial: ftdi_sio: only bind FT232H if UART mode is
 enabled

On Wed, Jul 19, 2017 at 01:23:27PM +0200, Anatolij Gustschin wrote:
> On Wed, 19 Jul 2017 11:03:11 +0200
> Johan Hovold johan@...nel.org wrote:
> 
> >On Thu, Jul 13, 2017 at 06:25:25PM +0200, Anatolij Gustschin wrote:
> >> On FT232H the interface mode can be configured in the EEPROM,
> >> and the async UART mode is configured by default. The chip is
> >> also in async UART mode if no EEPROM is connected.
> >> 
> >> Check the EEPROM configuration and do not bind as serial device
> >> when different interface mode is programmed in the EEPROM.  
> >
> >Thanks for the patch. As you may have inferred from my reply to your MFD
> >series, this won't be needed for a while still however.
> >
> >Also note that some people already use asynchronous FIFO mode using this
> >driver (also mentioned in the datasheets as an option) so only binding
> >in UART mode would be too restrictive.
> 
> You probably mean asynchronous bitbang mode, not asynchronous FIFO
> mode?

No, I really meant asynchronous FIFO mode. And as mentioned in the data
sheets that can be used with the normal serial (VCP) drivers on both
Linux and that other OS.

> This bitbang mode can always be set by sending a chip command
> (mentioned as software configured in the datasheets)
> Could you please point to code in this driver used for non-UART modes?
> I don't see such code by a quick glance. There are some quirks for
> various JTAG adapters to skip binding as serial port (the ftdi_sio
> driver is not used in JTAG operation modes then). Or do people use
> usual serial interface to send data in bitbang modes?

Exactly.

> Async and sync FIFO (FT245) modes however can only be configured via
> EEPROM settings, at least for FT232H.

Right.

Thanks,
Johan