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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 04262C433E0 for ; Fri, 29 May 2020 17:53:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2759207BC for ; Fri, 29 May 2020 17:53:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727961AbgE2Rxw (ORCPT ); Fri, 29 May 2020 13:53:52 -0400 Received: from bmailout1.hostsharing.net ([83.223.95.100]:43311 "EHLO bmailout1.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725913AbgE2Rxw (ORCPT ); Fri, 29 May 2020 13:53:52 -0400 Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.hostsharing.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (not verified)) by bmailout1.hostsharing.net (Postfix) with ESMTPS id CA78C30000D1D; Fri, 29 May 2020 19:53:50 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 9D537FA4C1; Fri, 29 May 2020 19:53:50 +0200 (CEST) Date: Fri, 29 May 2020 19:53:50 +0200 From: Lukas Wunner To: Florian Fainelli Cc: Nicolas Saenz Julienne , Mark Brown , Ray Jui , Scott Branden , bcm-kernel-feedback-list@broadcom.com, Martin Sperl , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] spi: bcm2835: Enable shared interrupt support Message-ID: <20200529175350.2wtoqttipa354m2m@wunner.de> References: <20200528185805.28991-1-nsaenzjulienne@suse.de> <20200529174358.som3snunfxch6phi@wunner.de> <36dd65bb-18a9-9697-b9b6-76eaf8cbe45c@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <36dd65bb-18a9-9697-b9b6-76eaf8cbe45c@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 29, 2020 at 10:46:01AM -0700, Florian Fainelli wrote: > On 5/29/20 10:43 AM, Lukas Wunner wrote: > > On Thu, May 28, 2020 at 08:58:04PM +0200, Nicolas Saenz Julienne wrote: > >> --- a/drivers/spi/spi-bcm2835.c > >> +++ b/drivers/spi/spi-bcm2835.c > >> @@ -379,6 +379,10 @@ static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) > >> if (bs->tx_len && cs & BCM2835_SPI_CS_DONE) > >> bcm2835_wr_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE); > >> > >> + /* check if we got interrupt enabled */ > >> + if (!(bcm2835_rd(bs, BCM2835_SPI_CS) & BCM2835_SPI_CS_INTR)) > >> + return IRQ_NONE; > >> + > >> /* Read as many bytes as possible from FIFO */ > >> bcm2835_rd_fifo(bs); > >> /* Write as many bytes as possible to FIFO */ [...] > > Finally, it would be nice if the check would be optimized away when > > compiling for pre-RasPi4 products, maybe something like: > > > > + if (IS_ENABLED(CONFIG_ARM_LPAE) && !(cs & BCM2835_SPI_CS_INTR)) > > + return IRQ_NONE; > > Rather than keying this off ARM_LPAE or any other option, this should be > keyed off a compatible string, that way we can even conditionally pass > IRQF_SHARED to the interrupt handler if we care so much about performance. But a compatible string can't be checked at compile time, can it? The point is that at the least the Foundation compiles and ships a separate kernel for each of the three platforms BCM2835, BCM2837, BCM2711. It's unnecessary to check whether an interrupt was actually raised if we *know* in advance that it's not shared (as is the case with kernels compiled for BCM2835 and BCM2837). Thanks, Lukas