Messages in this thread | | | From | Felipe Balbi <> | Subject | Re: [PATCH 1/2] usb: typec: Add USB Power Delivery sink port support | Date | Fri, 15 Jul 2016 13:38:12 +0300 |
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Hi,
Bin Gao <bin.gao@linux.intel.com> writes: > +static void print_message(int port, bool is_cmsg, u8 msg, bool recv) > +{ > + pr_info("sink port %d: %s message %s %s\n", port, > + is_cmsg ? "Control" : "Data", > + msg_to_string(is_cmsg, msg), > + recv ? "received" : "sent(wait GOODCRC)"); > +}
this is problematic. By default, we're all using 115200 8N1 baud rate. This message alone prints anywhere from 50 to 100 characters (I didn't really count properly, these are rough numbers), and that takes:
n50chars_time = 50 / (115200 / 10) = 4.3ms n100chars_time = 100 / (115200 / 10) = 8.6ms
Considering you have 30ms to reply with Power Request after GoodCRC, and considering you're printing several of these messages, they become really expensive and eat up valuable time from tSenderReply.
This should really be a pr_debug() or, better yet, a tracepoint.
-- balbi [unhandled content-type:application/pgp-signature]
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