lkml.org 
[lkml]   [2016]   [Jul]   [18]   [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,

Bin Gao <bin.gao@linux.intel.com> writes:
>> > +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?
> Some Type-C chargers send two messages in a short duration(less than 1 ms),
> e.g. a SOURCE_CAPABILITY follows the previous SOURCE_CAPABILITY, or a
> GET_SINK_CAPABILITY follows a previous SOURCE_CAPABILITY, etc. Queuing
> message to PD stack by Type-C phy driver typically happens in a interrupt
> context. So in this case a nested interrupt may happen. Our whole PD
> stack while processing one message is not re-entrant so the nested
> interrupt would cause a problem.

keep interrupts masked for as long as necessary until your message is
processed.

--
balbi
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2016-07-18 09:41    [W:0.117 / U:8.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site