On Thu, 3 Mar 2016, Johan Hovold wrote:
On Wed, Mar 02, 2016 at 09:36:55AM -0800, Aaron Marburg wrote:
On Wed, 2 Mar 2016, Oliver Neukum wrote:
On Tue, 2016-03-01 at 09:54 -0800, amarburg@xxxxxxxxxxxxxxxxxx wrote:
From: Aaron Marburg <amarburg@xxxxxxxxxxxxxxxxxx>
The USOPTL4-4P and USOPTL4-2P USB-to-quad/dual RS-485/422 hubs use the
Moschip 7840/7820. For correct operation in RS-485, the chip must be
configured in “RS-485 mode” through the scratchpad register as per the
datasheet. This strobes the DTR line on transmission, enabling the driver
on the RS485 transceiver chip.
I think if you include a config option to do this, you should
also enable the canonical way of using an ioctl(). That means
you need to support rs485_config().
Regards
Oliver
Thank you for that pointer, I was not familiar with that IOCTL. I will
see what's required for implementation.
Yeah, we really don't want to add new module options. Either see if you
can make this fit with the rs485 ioctl, or do this based on the
driver_data field in the id_table (e.g. set a feature flags there) as we
don't want to sprinkle the driver with ID-conditionals.
The ioctl is the right approach. I'll implement the appropriate
callbacks. I will also look into a feature-flag option. As far as I
know, these particular B&B hubs will only work in RS485 mode, so I believe
it makes sense to enable RS485 by default for those models.
Thanks,
Aaron
