Re: [PATCH V6 1/1] usb:serial: Add Fintek F81532/534 driver

[Peter Hung]

Hi,

Oliver Neukum æ 2015/11/4 äå 04:38 åé:
> On Wed, 2015-11-04 at 16:19 +0800, Peter Hung wrote:
> > Hi
> >
> > Oliver Neukum æ 2015/11/3 äå 06:03 åé:
> > > On Tue, 2015-11-03 at 11:51 +0800, Peter Hung wrote:
> > > > +	for (i = 0; i < F81534_NUM_PORT; ++i)
> > > > +		atomic_set(&serial_priv->port_active[i], 0);
> > >
> > > Should be ATOMIC_INIT()
> >
> > ATOMIC_INIT() seems to be used only for variable initializer, It cant be
> > used for dynamic allocation. Should I change it to a normal boolean
> > flag protecting with spin_lock ?
>
> No, if it doesn't work, use the current code.

OK, I'll use current code.

> > > > +static void f81534_compare_msr(struct usb_serial_port *port, u8 *msr,
> > >
> > > Is the point of passing a pointer to msr locking?
> > >
> > > > +				bool is_port_open)
> >
> > This function is used only with URB callback function. The *msr is
> > reported by H/W with newest MSR. The USB-Serial generic system will
> > re-submit read URB when callback complete. So this function should
> > run once on the same time.
>
> Yes, so why don't you pass an u8 as opposed to a pointer to an u8?

I'll re-write it from u8* to u8.

> > > > +static int f81534_tiocmget(struct tty_struct *tty)
> > > > +{
> > > > +	struct usb_serial_port *port = tty->driver_data;
> > > > +	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
> > > > +	unsigned long flags;
> > > > +	int r;
> > > > +	u8 msr, mcr;
> > > > +
> > > > +	/*
> > > > +	 * We'll avoid to direct read MSR register. The IC will read the MSR
> > > > +	 * changed and report it f81534_process_per_serial_block() by
> > > > +	 * F81534_TOKEN_MSR_CHANGE.
> > > > +	 *
> > > > +	 * When this device in heavy loading (e.g., BurnInTest Loopback Test)
> > > > +	 * The report of MSR register will delay received a bit. It's due to
> > > > +	 * MSR interrupt is lowest priority in 16550A. So we decide to sleep
> > > > +	 * a little time to pass the test.
> > > > +	 */
> > > > +	if (schedule_timeout_interruptible(
> > > > +			msecs_to_jiffies(F81534_DELAY_READ_MSR))) {
> > > > +		dev_info(&port->dev, "%s: breaked !!\n", __func__);
> > > > +	}
> > >
> > > Is the delay necessary or isn't it?
> > > If it is necessary you should do something about the signal.
> >
> > We add this delay due to stress test (Loop-back & 921600bps with
> > BurnInTest). It'll receive MSR with some delay when connecting with
> > DTR-DSR & RTS/CTS, but the delay smaller than 10ms. So we decided to
> > delay some time to pass the test.
>
> OK, but how do you guarantee the delay you need if you get a signal,
> which would abort the delay?

Hmm, you are right. It seems to replace *_interruptible to
*_killable and return -EINTR to guarantee not abort by normal
signal.


Thanks for your advices
--
With Best Regards,
Peter Hung
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