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 X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 090FAC61CE4 for ; Sun, 20 Jan 2019 11:08:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BEF132087B for ; Sun, 20 Jan 2019 11:08:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547982498; bh=6JOgy4qD6CGxl1OspXO/aQD9Cs9w19R36CZSfUz0tXQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=04ja4BEa66UyMR1IHDArBzf4f+L73TBIzn+8Hd1HfxZEl2OWO8v4y5rw6m5/SBcly KoUePH50zOnMwrTeQkrps6BXYjzWEdz/ewsCVDEecoOL1vRJV5G6vfOy36FjF9nH1n czE9jz8Mc1fhIzLtkqlc9u3Q0RCEblJHpqjqHaqg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730505AbfATLIR (ORCPT ); Sun, 20 Jan 2019 06:08:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:55368 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728894AbfATLIQ (ORCPT ); Sun, 20 Jan 2019 06:08:16 -0500 Received: from localhost (unknown [122.178.235.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C52142084F; Sun, 20 Jan 2019 11:08:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547982495; bh=6JOgy4qD6CGxl1OspXO/aQD9Cs9w19R36CZSfUz0tXQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Lq8do58y2AIluPJnZqsjM+Byrz0YTx2J+KW/bu1y0UR1hRFl02RUCKOtKcYQQi5NV E/GaEaSLuGk48qNxMcfpB9SLKAekA0PrsX/Zn43xR3Oj1w6HOfECHOwtZTWAu2golS 5ePGcvSgexWDEbxAGDFvLsFZlttU/UXq9+5GsWpc= Date: Sun, 20 Jan 2019 16:36:42 +0530 From: Vinod Koul To: John Stultz Cc: Manivannan Sadhasivam , lkml , Rob Herring , Mark Rutland , Tanglei Han , Zhuangluan Su , Ryan Grachek , "open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM" , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" Subject: Re: [PATCH 2/8 v4] Documentation: bindings: dma: Add binding for dma-channel-mask Message-ID: <20190120110642.GT4635@vkoul-mobl> References: <1547658629-25378-1-git-send-email-john.stultz@linaro.org> <1547658629-25378-3-git-send-email-john.stultz@linaro.org> <20190117170829.GJ5283@Mani-XPS-13-9360> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17-01-19, 09:43, John Stultz wrote: > On Thu, Jan 17, 2019 at 9:08 AM Manivannan Sadhasivam > wrote: > > > > On Wed, Jan 16, 2019 at 09:10:23AM -0800, John Stultz wrote: > > > Some dma channels can be reserved for secure mode or other > > > hardware on the SoC, so provide a binding for a bitmask > > > listing the available channels for the kernel to use. > > > > > > This follows the pre-existing bcm,dma-channel-mask binding. > > > > > > Cc: Vinod Koul > > > Cc: Rob Herring > > > Cc: Mark Rutland > > > Cc: Tanglei Han > > > Cc: Zhuangluan Su > > > Cc: Ryan Grachek > > > Cc: Manivannan Sadhasivam > > > Cc: dmaengine@vger.kernel.org > > > Cc: devicetree@vger.kernel.org > > > Signed-off-by: John Stultz > > > --- > > > v3: Renamed to hisi-dma-avail-chan > > > v4: Reworked to generic dma-channel-mask > > > --- > > > Documentation/devicetree/bindings/dma/dma.txt | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/dma/dma.txt b/Documentation/devicetree/bindings/dma/dma.txt > > > index 6312fb0..eeb4e4d 100644 > > > --- a/Documentation/devicetree/bindings/dma/dma.txt > > > +++ b/Documentation/devicetree/bindings/dma/dma.txt > > > @@ -16,6 +16,9 @@ Optional properties: > > > - dma-channels: Number of DMA channels supported by the controller. > > > - dma-requests: Number of DMA request signals supported by the > > > controller. > > > +- dma-channel-mask: Bitmask of available DMA channels in ascending order > > > + that are not reserved by firmware and are available to > > > + the kernel. i.e. first channel corresponds to LSB. > > > > A general assumption is, "dma-channel-mask" refers to the bit fields of > > the channels which needs to be masked. But here, it refers to the channels > > which are available. Doesn't it contradict? > > Hrm. So while I can sort of understand the common usage of "mask" as > to "hide", thus the desire to have a bitfield mean "the channels we > hide" or "don't use", but in my experience bitmasking is more commonly > used to keep only a portion of the the bits, so from that perspective > its more intuitive that a mask be the channels we keep to use. So I'm > not sure if your suggestion makes it more clear. > > But I'm not very particular here, so I'll defer to others on this. Given the context and documentation which explicitly says it is bitmask of available channels, i think we are fine :) -- ~Vinod