linux-kernel - Re: [PATCH v3] Bluetooth: hci_uart: Support firmware download for Marvell

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Date:	Tue, 1 Mar 2016 21:59:24 +0000
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Amitkumar Karwar <akarwar@...vell.com>
Cc:	<linux-bluetooth@...r.kernel.org>, Cathy Luo <cluo@...vell.com>,
	<linux-kernel@...r.kernel.org>,
	Nishant Sarmukadam <nishants@...vell.com>,
	Ganapathi Bhat <gbhat@...vell.com>
Subject: Re: [PATCH v3] Bluetooth: hci_uart: Support firmware download for
 Marvell

O
> +/* Get standard baud rate, given the speed */
> +static unsigned int get_baud_rate(unsigned int speed)
> +{
> +	switch (speed) {
> +	case 9600:
> +		return B9600;
> +	case 19200:
> +		return B19200;
> +	case 38400:
> +		return B38400;
> +	case 57600:
> +		return B57600;
> +	case 115200:
> +		return B115200;
> +	case 230400:
> +		return B230400;
> +	case 460800:
> +		return B460800;
> +	case 921600:
> +		return B921600;
> +	case 2000000:
> +		return B2000000;
> +	case 3000000:
> +		return B3000000;
> +	default:
> +		return -1;
> +	}
> +}


NAK. Please use the existing kernel helpers for this


 +
> +/* Set terminal properties */
> +static int mrvl_set_term_baud(struct tty_struct *tty, unsigned int speed,
> +			      unsigned char flow_ctl)
> +{
> +	struct ktermios old_termios = tty->termios;
> +	int baud;
> +
> +	tty->termios.c_cflag &= ~CBAUD;
> +	baud = get_baud_rate(speed);
> +
> +	if (baud == -1) {
> +		BT_ERR("Baud rate not supported");
> +		return -1;
> +	}
> +
> +	tty->termios.c_cflag |= baud;
> +

This isn't the correct way to do any of this, just do

	tty_termios_encode_baud_rate(&tty->termios, speed, speed)


> +	if (flow_ctl)
> +		tty->termios.c_cflag |= CRTSCTS;
> +	else
> +		tty->termios.c_cflag &= ~CRTSCTS;
> +
> +	tty->ops->set_termios(tty, &old_termios);

Call the provided kernel helpers that get the locking right.

tty_set_termios(tty, &new_termios);

You should also do your error checking here and see what baud rate was
actually provided by the hardware (tty_get_baud_rate(tty)) by checking
the value actually selected by the tty.

> +	/* restore uart settings */
> +	new_termios = tty->termios;
> +	tty->termios.c_cflag = old_termios.c_cflag;
> +	tty->ops->set_termios(tty, &new_termios);
> +	clear_bit(HCI_UART_DNLD_FW, &hu->flags);

Again use the proper helpers

> +
> +set_baud:
> +	ret = mrvl_set_baud(hu);
> +	if (ret)
> +		goto fail;
> +
> +	mdelay(MRVL_DNLD_DELAY);

Why not msleep() ?

> +
> +	return ret;
> +fail:
> +	/* restore uart settings */
> +	new_termios = tty->termios;
> +	tty->termios.c_cflag = old_termios.c_cflag;
> +	tty->ops->set_termios(tty, &new_termios);
> +	clear_bit(HCI_UART_DNLD_FW, &hu->flags);
> +

Ditto...

Alan