Re: [PATCH 3/6] net: ethernet: ti: cpts: add support of cpts HW_TS_PUSH

From: Grygorii Strashko
Date: Thu Dec 08 2016 - 14:04:20 EST

On 12/03/2016 05:21 PM, Richard Cochran wrote:
> On Mon, Nov 28, 2016 at 05:04:25PM -0600, Grygorii Strashko wrote:
>> This also change overflow polling period when HW_TS_PUSH feature is
>> enabled - overflow check work will be scheduled more often (every
>> 200ms) for proper HW_TS_PUSH events reporting.
> For proper reporting, you should make use of the interrupt. The small
> fifo (16 iirc) could very well overflow in 200 ms. The interrupt
> handler should read out the entire fifo at each interrupt.

huh. Seems this is not really good idea, because MISC Irq will be
triggered for *any* CPTS event and there is no way to enable it just for
HW_TS_PUSH. So, this doesn't work will with current code for RX/TX timestamping
(which uses polling mode). + runtime overhead in net RX/TX caused by
triggering more interrupts.

May be, overflow check/polling timeout can be made configurable (module parameter).