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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BA1D6C433F5 for ; Tue, 14 Dec 2021 10:51:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=qB/oKtDBvq334avnNCcDXKIKI8TqImuzay+al551jKA=; b=GKKYQrlCXgyOMp vKIqaEqw3WTxU87LY3QL1Rlf2+ndgiSkrjF9m0BVvExmVL+lyz+c8BaB/yRPBaT+TGoIGI1kHebkd uyd8G5h+jIJAIvQlGXJ56fsU9pj6RFt52qAwFbswn8BVFzxGGi4ivHYf0/N249q6QYpnCrqxwVpt0 aG47o90hMnfJh56zAe/UpU+uklqL1x91BOFERMZAPIMteGQX8GJbr1oOpGroEQG9F4eqGRd3cSrPH 2x3V9CJdfRaBZvcmab6I16Ek7nTElFDf72W7jkKFExU/veIJ3X30aqaNdory/T+tT6/+mDcoLzTLP 5zhbrrOxkUVN19tr+VRA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mx5No-00DXsU-8f; Tue, 14 Dec 2021 10:50:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mx5Nj-00DXjb-0g for linux-arm-kernel@lists.infradead.org; Tue, 14 Dec 2021 10:50:05 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B05E26D; Tue, 14 Dec 2021 02:49:57 -0800 (PST) Received: from e120937-lin (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6138A3F5A1; Tue, 14 Dec 2021 02:49:56 -0800 (PST) Date: Tue, 14 Dec 2021 10:49:49 +0000 From: Cristian Marussi To: Sudeep Holla Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com, f.fainelli@gmail.com, etienne.carriere@linaro.org, vincent.guittot@linaro.org, souvik.chakravarty@arm.com Subject: Re: [PATCH v7 06/16] firmware: arm_scmi: Add configurable polling mode for transports Message-ID: <20211214104949.GE6207@e120937-lin> References: <20211129191156.29322-1-cristian.marussi@arm.com> <20211129191156.29322-7-cristian.marussi@arm.com> <20211213112555.vhjhu3xopesvxmio@bogus> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20211213112555.vhjhu3xopesvxmio@bogus> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211214_025003_196008_08506F16 X-CRM114-Status: GOOD ( 31.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Dec 13, 2021 at 11:25:55AM +0000, Sudeep Holla wrote: > On Mon, Nov 29, 2021 at 07:11:46PM +0000, Cristian Marussi wrote: > > SCMI communications along TX channels can optionally be provided of a > > completion interrupt; when such interrupt is not available, command > > transactions should rely on polling, where the SCMI core takes care to > > repeatedly evaluate the transport-specific .poll_done() function, if > > available, to determine if and when a request was fully completed or > > timed out. > > Hi Sudeep, thanks for the review. > > Such mechanism is already present and working on a single transfer base: > > SCMI protocols can indeed enable hdr.poll_completion on specific commands > > ahead of each transfer and cause that transaction to be handled with > > polling. > > > > Introduce a couple of flags to be able to enforce such polling behaviour > > globally at will: > > > > - scmi_desc.force_polling: to statically switch the whole transport to > > polling mode. > > > > - scmi_chan_info.no_completion_irq: to switch a single channel dynamically > > to polling mode if, at runtime, is determined that no completion > > interrupt was available for such channel. > > > > Signed-off-by: Cristian Marussi > > --- > > v5 --> v6 > > - removed check on replies received by IRQs when xfer was requested > > as poll_completion (not all transport can suppress IRQs on an xfer basis) > > v4 --> v5 > > - make force_polling const > > - introduce polling_enabled flag to simplify checks on do_xfer > > v3 --> v4: > > - renamed .needs_polling flag to .no_completion_irq > > - refactored error path when polling needed but not supported > > --- > > drivers/firmware/arm_scmi/common.h | 11 +++++++++++ > > drivers/firmware/arm_scmi/driver.c | 17 +++++++++++++++++ > > 2 files changed, 28 insertions(+) > > > > diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h > > index 6438b5248c24..99b74f4d39b6 100644 > > --- a/drivers/firmware/arm_scmi/common.h > > +++ b/drivers/firmware/arm_scmi/common.h > > @@ -339,11 +339,19 @@ void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id); > > * @dev: Reference to device in the SCMI hierarchy corresponding to this > > * channel > > * @handle: Pointer to SCMI entity handle > > + * @no_completion_irq: Flag to indicate that this channel has no completion > > + * interrupt mechanism for synchronous commands. > > + * This can be dynamically set by transports at run-time > > + * inside their provided .chan_setup(). > > + * @polling_enabled: Flag used to annotate if polling mode is currently enabled > > + * on this channel. > > * @transport_info: Transport layer related information > > */ > > struct scmi_chan_info { > > struct device *dev; > > struct scmi_handle *handle; > > + bool no_completion_irq; > > + bool polling_enabled; > > Do we really need a separate flag for polling_enabled ? > no_completion_irq means you need to enable polling and force_polling too. > Just trying to see if we can get rid of unnecessary flags. > Not really needed indeed, I was just trying to avoid multiple conditions checks later on the TX path (given no_completion_irq and force_polling never change after channel setup so I can just note down at setup that polling is enabled and then just check that later) and improve readability, but I can just use macros for readability and just ignore the multiple unneeded checks. Same holds later on the series for polling_capable flag that I similarly setup early during probe to avoid unneeded multiple condition checks. I'll remove both this internal flags and resort to macros, if it's fine for you. Thanks, Cristian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel