linux-kernel - RE: [PATCH v7] Bluetooth: hci_uart: Support firmware download for Marvell

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Message-ID: <a0f486dd631c44b989f125c8a2e0050e@SC-EXCH04.marvell.com>
Date:	Tue, 26 Apr 2016 10:39:23 +0000
From:	Amitkumar Karwar <akarwar@...vell.com>
To:	Marcel Holtmann <marcel@...tmann.org>
CC:	Linux Bluetooth <linux-bluetooth@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ganapathi Bhat <gbhat@...vell.com>,
	Cathy Luo <cluo@...vell.com>
Subject: RE: [PATCH v7] Bluetooth: hci_uart: Support firmware download for
 Marvell

Hi Marcel,

> From: Marcel Holtmann [mailto:marcel@...tmann.org]
> Sent: Friday, April 22, 2016 6:19 PM
> To: Amitkumar Karwar
> Cc: Linux Bluetooth; LKML; Ganapathi Bhat; Cathy Luo
> Subject: Re: [PATCH v7] Bluetooth: hci_uart: Support firmware download
> for Marvell
> 
> Hi Amitkumar,
> 
> >>>> +
> >>>> +static int mrvl_setup(struct hci_uart *hu) {
> >>>> +	struct mrvl_data *mrvl = hu->priv;
> >>>> +
> >>>> +	mrvl_init_fw_data(hu);
> >>>> +	set_bit(HCI_UART_DNLD_FW, &mrvl->flags);
> >>>> +
> >>>> +	return hci_uart_dnld_fw(hu);
> >>>> +}
> >>>
> >>> So this is clearly the wrong spot. When ->setup is called it is
> >>> expected that HCI is ready. You are misusing it here.
> >>>
> >>
> >> Sure. We will move this to mrvl_open() where HCI is not yet
> initialized.
> >
> > We tried moving firmware download to mrvl_open(), but it's not
> feasible. "hu->proto" is not yet initialized at that time. So when the
> data/ack is received during firmware download, we can't have Marvell
> specific handling. Also, I can see other vendor's (broadcomm, Intel)
> have done firmware download in setup handler.
> 
> firmware download in ->setup() is fine as long as it uses HCI commands.
> If it does not use HCI commands, then we need to come up with something
> new.
> 
> The problem here is that for all intense and purposes once ->setup() is
> called, then assumption is that you are in an HCI capable transport and
> it is ready.
> 

I understand your concern. We are now planning to add new handler called "->prepare" where we can do firmware download. We are working on the change. Meanwhile let us know if you have any suggestion.

---------hci_ldisc.c---------
@@ -641,6 +641,10 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
        hu->proto = p;
        set_bit(HCI_UART_PROTO_READY, &hu->flags);

+       err = p->prepare(hu);
+       if (err)
+               return err;
+
        err = hci_uart_register_dev(hu);
        if (err) {
---------------------------

Regards,
Amitkumar