Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752545AbdLGTu2 (ORCPT ); Thu, 7 Dec 2017 14:50:28 -0500 Received: from shards.monkeyblade.net ([184.105.139.130]:43218 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750922AbdLGTu0 (ORCPT ); Thu, 7 Dec 2017 14:50:26 -0500 Date: Thu, 07 Dec 2017 14:50:24 -0500 (EST) Message-Id: <20171207.145024.1434883857028947517.davem@davemloft.net> To: ivan.khoronzhuk@linaro.org 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 From: David Miller In-Reply-To: <20171207194855.GA3022@khorivan> References: <1512571278-13196-1-git-send-email-ivan.khoronzhuk@linaro.org> <20171206.163545.906490902377440615.davem@davemloft.net> <20171207194855.GA3022@khorivan> X-Mailer: Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 07 Dec 2017 11:50:26 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1619 Lines: 39 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.