Re: [RFC v2 8/9] Bluetooth: drop HCI_UART_INIT_PENDING support

[Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Mon, Jan 1, 2018 at 2:42 PM, Martin Blumenstingl
<martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org> wrote:
> The three-wire (H5) protocol is the only protocol which uses
> HCI_UART_INIT_PENDING.

I think I'd also found that this flag wasn't really needed.

> Unfortunately the benefits of using this flag are currently unknown. It
> was added in commit 9f2aee848fe6 ("Bluetooth: Add delayed init sequence
> support for UART controllers"). In my experiments (with the
> "rtk_hciattach" tool - a customized version of hciattach for Realtek
> chipsets) I started the tool before and after this patch while the
> Bluetooth chipset was disabled (by pulling it's enable GPIO LOW). In
> both cases hci0 was not created - thus HCI_UART_INIT_PENDING is not
> required in that case.
>
> Removing this code also has another benefit: hci_serdev.c does not
> support the delayed initialization / registration.

This statement is misleading. serdev *always* supports async init as
it forces async probe of drivers. It doesn't need to support the
private workq init mechanism. At least that was my intent.

> Thus the protocol
> implementation (hci_h5) never receives any data with this check still
> in place. For the H5 protocol this means that the initialization never
> completes (because the sync response never arrives). Even if the
> initialization would succeed later on the drivers would call
> hci_uart_init_ready() which schedules the registration which is
> currently not implemented by hci_serdev.c.
>
> Removing the HCI_UART_INIT_PENDING check makes the code easier to read
> and also fixes the initalization of devices (implemented with the serdev
> library) which use the H5 protocol.
>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
> ---
>  drivers/bluetooth/hci_h5.c     |  3 ---
>  drivers/bluetooth/hci_ldisc.c  | 38 --------------------------------------
>  drivers/bluetooth/hci_serdev.c |  3 ---
>  drivers/bluetooth/hci_uart.h   |  4 +---
>  4 files changed, 1 insertion(+), 47 deletions(-)