lkml.org 
[lkml]   [2016]   [Jul]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 1/2] usb: typec: Add USB Power Delivery sink port support
Date

Hi again,

Felipe Balbi <felipe.balbi@linux.intel.com> writes:
> Oliver Neukum <oneukum@suse.com> writes:
>> On Fri, 2016-07-15 at 10:25 +0300, Felipe Balbi wrote:
>>> > +int pd_sink_queue_msg(struct pd_sink_msg *msg)
>>> > +{
>>> > + unsigned long flags;
>>> > + struct pd_sink_port *port;
>>> > +
>>> > + if (msg->port < 0 || msg->port >= MAX_NR_SINK_PORTS) {
>>> > + pr_err("Invalid port number\n");
>>> > + return -EINVAL;
>>> > + }
>>> > +
>>> > + port = sink_ports[msg->port];
>>> > +
>>> > + spin_lock_irqsave(&port->rx_lock, flags);
>>> > + list_add_tail(&msg->list, &port->rx_list);
>>> > + spin_unlock_irqrestore(&port->rx_lock, flags);
>>> > +
>>> > + queue_work(port->rx_wq, &port->rx_work);
>>>
>>> can we really queue several messages at a time? It seems unfeasible to
>>> me. It's not like we can queue several power request in a role. Why do
>>> you need this workqueue? Why don't you process message here, in place?
>>
>> A reset can come at any time.
>
> right, but that's not how this is being used. IMHO, rx_work is a
> misnomer. If you look at how typec_wcove (patch 2 in this series) uses
> it, you'll see that pd_sink_queue_msg() is called to queue a reply to a
> message that was *already* received. We can't have two replies, right?
>
> In any case, this is a minor problem.

oh wait, it's not a minor problem. If CPU is busy, this workqueue might
take longer than 30ms to get scheduled. This is another problem I just
reproduced, even after changing that pr_info() in print_message() to a
pr_debug().

Everything worked fine when I called rx_msg_worker() directly, instead
of queueing it to the workqueue.

--
balbi
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2016-07-15 15:41    [W:0.065 / U:0.664 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site