From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB096C433F5 for ; Wed, 18 May 2022 15:47:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239568AbiERPrq (ORCPT ); Wed, 18 May 2022 11:47:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239534AbiERPrq (ORCPT ); Wed, 18 May 2022 11:47:46 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CCE2187046; Wed, 18 May 2022 08:47:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E5C3AB81FB7; Wed, 18 May 2022 15:47:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 271A6C385A5; Wed, 18 May 2022 15:47:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652888862; bh=bs9W7OCncR8gEQ1uTaOzOqEwcuKz+nCPcAJadJVgxNc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=UZO5OfN2DSJz+BoS0Xq/rGAZmjmQFfex307IwzNHldkA4Vv4MOaL7foOTDUtx5nrz lcrHqDjXUlzNbILx2j+RCzjKef4u+1+KU5nijpNWHslUOP0c7bBcdTJlpQrihfIDFP r9/RbSc7YCHUl5bZ3PS2GR1p85XvHNB941mxhRSFMX2gW5+FOKPtgkDgI8SpGC7fr1 gxKIO4d10CjWcuKxgpTV5YMrpI92I2YeFYESDvKGyAVDvZpVgBjVdxVfQBhU7x5+J3 FsCml0JYbo+G68tWS2N+jP7KeltVjyLy7aQ8AsdFaOfPe8hxfksyKvtSITNf9+FRvy 2OG72z6kkUvIw== Date: Wed, 18 May 2022 08:47:40 -0700 From: Jakub Kicinski To: Lorenzo Bianconi Cc: netdev@vger.kernel.org, nbd@nbd.name, john@phrozen.org, sean.wang@mediatek.com, Mark-MC.Lee@mediatek.com, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, Sam.Shih@mediatek.com, linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org, robh@kernel.org, lorenzo.bianconi@redhat.com Subject: Re: [PATCH v2 net-next 12/15] net: ethernet: mtk_eth_soc: introduce MTK_NETSYS_V2 support Message-ID: <20220518084740.7947b51b@kernel.org> In-Reply-To: References: <20220517184433.3cb2fd5a@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Wed, 18 May 2022 11:53:12 +0200 Lorenzo Bianconi wrote: > > > + WRITE_ONCE(desc->txd7, 0); > > > + WRITE_ONCE(desc->txd8, 0); > > > > Why all the WRITE_ONCE()? Don't you just need a barrier between writing > > the descriptor and kicking the HW? > > I used this approach just to be aligned with current codebase: > https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/mediatek/mtk_eth_soc.c#L1006 > https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/mediatek/mtk_eth_soc.c#L1031 > > but I guess we can even convert the code to use barrier instead. Agree? Oh, I didn't realize. No preference on converting the old code but it looks like a cargo cult to me so in the new code let's not WRITE_ONCE() all descriptor writes unless there's a reason.