Re: [PATCH v3 0/5] Serial slave device bus

From: Rob Herring
Date: Tue Jan 31 2017 - 10:46:28 EST

On Mon, Jan 30, 2017 at 11:44 PM, Sebastian Reichel <sre@xxxxxxxxxx> wrote:
> Hi,
> On Tue, Jan 31, 2017 at 04:02:41AM +0100, Sebastian Reichel wrote:
>> On Wed, Jan 25, 2017 at 02:23:38PM -0600, Rob Herring wrote:
>> > Here's V3 of the serdev bus support with all the review feedback so far
>> > incorporated. Greg applied the first 4 patches already. I also found a
>> > problem in the tty_port_wakeup changes and have fixed that.
>> >
>> > I've added serdev support to the BT hci_ll.c driver as it turns out it works
>> > on newer TI chips too, but just needed firmware loading. That avoids the
>> > impossible mess of cleaning up the TI-ST driver, and it's in a much closer
>> > state to being ready for upstream. I've sent that out separately.
>> >
>> > Changelog is in individual patches. Previous versions are here[1][2]. This
>> > series and the mentioned drivers can be found here[3].
>> >
>> > Rob
>> >
>> > [1]
>> > [2]
>> > [3] git:// serial-bus-v4
>> I rebased my nokia bluetooth driver on top of [3]. It's not yet
>> working, but everything added by this patchset (and
>> "bluetooth: hci_uart: add serdev driver support library") seems
>> to work as expected, so for the whole series:
>> Tested-By: Sebastian Reichel <sre@xxxxxxxxxx>


> FWIW, I got bluetooth on top of your patchset working on N950. N900
> is not yet tested and probably does not yet work (it's more picky
> about flow control and usage of the wakeup gpios). You can find a
> branch with the additional patches @ [4]. I had to add serdev
> functions to wait for TX buffer depletion and checking CTS. Apart
> from that flow control only worked correctly when also taking care
> of RTS (like hci_uart_set_flow_control does).

I'd originally copied hci_uart_set_flow_control, but then realized
that it didn't really do what I wanted. What I have now is turn on or
off h/w control (i.e. off is no RTS/CTS signals connected). What
hci_uart_set_flow_control does is enable h/w flow control
(enable=false) or force assert RTS (enable=true). I guess it didn't
help that I used the same _set_flow_control naming with different
behavior. I did expect we'd also need something for RTS control, but
figured we'd add it as needed and wanted to come up with something a
bit clearer as to the function (i.e. serdev_device_pause_rx or

> I noticed, that you did not yet write any DT bindings for your
> bluetooth slaves. Did you already decide for a location?

Marvell BT is already in bindings/net/.


> [4] git:// serial-bus-v4-nokia-bt
> -- Sebastian