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

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Date:   Wed, 19 Jul 2017 13:23:27 +0200
From:   Anatolij Gustschin <agust@...x.de>
To:     Johan Hovold <johan@...nel.org>
Cc:     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, 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? 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?

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

Thanks,
Anatolij