From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752214AbdLGUKM (ORCPT ); Thu, 7 Dec 2017 15:10:12 -0500 Received: from mail-lf0-f66.google.com ([209.85.215.66]:43081 "EHLO mail-lf0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750862AbdLGUKK (ORCPT ); Thu, 7 Dec 2017 15:10:10 -0500 X-Google-Smtp-Source: AGs4zMapi28j/vRap5qi5aJO11gZL6FHwN+0xfOV/g4mnMEEyTubw/yuXJL0hXQcpboPwvnUjgyB1Q== Date: Thu, 7 Dec 2017 22:10:06 +0200 From: Ivan Khoronzhuk To: David Miller Cc: grygorii.strashko@ti.com, netdev@vger.kernel.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] net: ethernet: ti: cpdma: rate is not changed - correct case Message-ID: <20171207201005.GC3022@khorivan> Mail-Followup-To: David Miller , grygorii.strashko@ti.com, netdev@vger.kernel.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org References: <1512571278-13196-1-git-send-email-ivan.khoronzhuk@linaro.org> <20171206.163545.906490902377440615.davem@davemloft.net> <20171207194855.GA3022@khorivan> <20171207.145024.1434883857028947517.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171207.145024.1434883857028947517.davem@davemloft.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 07, 2017 at 02:50:24PM -0500, David Miller wrote: > From: Ivan Khoronzhuk > Date: Thu, 7 Dec 2017 21:48:56 +0200 > > > On Wed, Dec 06, 2017 at 04:35:45PM -0500, David Miller wrote: > >> From: Ivan Khoronzhuk > >> Date: Wed, 6 Dec 2017 16:41:18 +0200 > >> > >> > If rate is the same as set it's correct case. > >> > > >> > Signed-off-by: Ivan Khoronzhuk > >> > --- > >> > Based on net-next/master > >> > > >> > drivers/net/ethernet/ti/davinci_cpdma.c | 2 +- > >> > 1 file changed, 1 insertion(+), 1 deletion(-) > >> > > >> > diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c > >> > index e4d6edf..dbe9167 100644 > >> > --- a/drivers/net/ethernet/ti/davinci_cpdma.c > >> > +++ b/drivers/net/ethernet/ti/davinci_cpdma.c > >> > @@ -841,7 +841,7 @@ int cpdma_chan_set_rate(struct cpdma_chan *ch, u32 rate) > >> > return -EINVAL; > >> > > >> > if (ch->rate == rate) > >> > - return rate; > >> > + return 0; > >> > >> Looking at the one and only caller of this function, cpsw_ndo_set_tx_maxrate, it > >> makes sure this can never, ever, happen. > > In current circumstances yes, it will never happen. > > But I caught it while adding related code and better return 0 if upper caller > > doesn't have such check. Suppose that cpdma module is responsible for itself > > and if it's critical I can send this patch along with whole related series. > > You have to decide one way or the other, who is responsible. > > I think checking higher up is better because it's cheaper at that point to > look at the per-netdev queue rate setting before moving down deeper into the > driver specific data-structures. No objection, but upper caller not always knows current rate and for doing like this it needs read it first, and this is also some redundancy. -- Regards, Ivan Khoronzhuk