linux-kernel - Re: [PATCH 3/6] net: ethernet: ti: cpts: add support of cpts HW_TS

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Message-ID: <20161209085037.GA16009@localhost.localdomain>
Date:   Fri, 9 Dec 2016 09:50:37 +0100
From:   Richard Cochran <richardcochran@...il.com>
To:     Grygorii Strashko <grygorii.strashko@...com>
Cc:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Mugunthan V N <mugunthanvnm@...com>,
        Sekhar Nori <nsekhar@...com>, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        devicetree@...r.kernel.org, Murali Karicheri <m-karicheri2@...com>,
        Wingman Kwok <w-kwok2@...com>
Subject: Re: [PATCH 3/6] net: ethernet: ti: cpts: add support of cpts
 HW_TS_PUSH

On Thu, Dec 08, 2016 at 01:04:11PM -0600, Grygorii Strashko wrote:
> 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 what?  That is not a problem.

> So, this doesn't work will with current code for RX/TX timestamping
> (which uses polling mode).

Why doesn't it work?

> + runtime overhead in net RX/TX caused by 
> triggering more interrupts. 

This is not relevant.  Without HW_TS_PUSH, there is no need for
enabling the interrupt simply because we don't need it.  Now, with
HW_TS_PUSH, we do need it.
 
> May be, overflow check/polling timeout can be made configurable (module parameter). 

No, it should just work without any user space fiddling.

I getting a bit tired of your half-baked implementations of the
ancillary clock functions.  Either do it right, or just leave it
unsupported.

Thanks,
Richard