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 A0815C4332F for ; Sun, 13 Nov 2022 22:23:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235458AbiKMWX5 (ORCPT ); Sun, 13 Nov 2022 17:23:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55724 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235447AbiKMWX4 (ORCPT ); Sun, 13 Nov 2022 17:23:56 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B88D925C1; Sun, 13 Nov 2022 14:23:55 -0800 (PST) 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 275E1B80CB8; Sun, 13 Nov 2022 22:23:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8072C433C1; Sun, 13 Nov 2022 22:23:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668378232; bh=qy55WPYerqcowUha2cX++DDpKUAHFQlKC0fdFGVcpHw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SoQ/8IZXKeJoAmMxfCyyKF45rJlVx7biYRJuwEa1vHJV+4VpmfIQJZU310sVIY461 UyETUaEUL8pGSUYDnT5bL+wvSW9ndL0E7OfHKaVlxpUl1Gs/CI2MnkW3ORaFnkDB4S S7pizrgGDcS7NdbCPoe0rpol9vBOoYaDFhDarwxk0PhW8Na42UWF216GK6mMT7pS4/ EgKyf0waOMFEZugZQfRz7wosYxYbPIyF8O5nwO987MxYz9LOm8vs+VSyFuFDxEzXnU 7hGcgbCwaWcz0/keEnJhCZS0rVYtNdMsFVWqPnOTf5G3+/2GLOHcrEIaY3gI0fagRG X0BKamPIfaA5w== Date: Mon, 14 Nov 2022 03:53:48 +0530 From: Vinod Koul To: Sireesh Kodali Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-msm@vger.kernel.org, dmaengine@vger.kernel.org, ~postmarketos/upstreaming@lists.sr.ht Subject: Re: [PATCH v2 0/3] dmaengine: Add support for immediate commands Message-ID: References: <20221027051429.46593-1-sireeshkodali1@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 11-11-22, 10:42, Sireesh Kodali wrote: > On Fri Nov 4, 2022 at 6:10 PM IST, Vinod Koul wrote: > > On 27-10-22, 10:44, Sireesh Kodali wrote: > > > The IPA v2.x block, found on some older Qualcomm SoCs, uses BAM DMA to > > > send and receive packets from the AP. It also uses BAM to receive > > > commands from the AP (and possibly the modem). These commands are > > > encoded as "Immediate Commands". They vary from regular BAM DMA > > > commands. Adding support for immediate commands is trivial, but requires > > > also adding Immediate Commands to the dmaengine API, which is what this > > > patch series does. > > > > Can you explain a bit more. I understand you need "Immediate Commands" > > but am really reluctant to add another interface to support a specific > > use case > > > > Apologies for the delayed response > > BAM supports both regular commands, and "immediate commands". Currently, > commands are used by the Qualcom NAND chip driver, while "immediate > commands" are intended to be used by the (yet to be mainlined) IPA > driver. From the BAM driver perspective, both immediate and regular > commands are simply a matter of setting the appropriate flag in the > descriptor. I don't have access to the documentation on BAM to know > exactly how these two modes differ, however I do know they are not > interchangable. If a different API is suggested, I can change the > implementation as needed. Ok, can you please explain what is meant by 'regular' cmd and 'immediate', lets see what is required here -- ~Vinod