From patchwork Sat Aug 3 10:10:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Lukas Wunner X-Patchwork-Id: 11074379 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E3E0F17E0 for ; Sat, 3 Aug 2019 10:43:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D5E4B288E5 for ; Sat, 3 Aug 2019 10:43:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C9A33288F4; Sat, 3 Aug 2019 10:43:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 70BA1288E5 for ; Sat, 3 Aug 2019 10:43:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388849AbfHCKnw (ORCPT ); Sat, 3 Aug 2019 06:43:52 -0400 Received: from mailout1.hostsharing.net ([83.223.95.204]:46141 "EHLO mailout1.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388809AbfHCKnv (ORCPT ); Sat, 3 Aug 2019 06:43:51 -0400 X-Greylist: delayed 471 seconds by postgrey-1.27 at vger.kernel.org; Sat, 03 Aug 2019 06:43:49 EDT Received: from h08.hostsharing.net (h08.hostsharing.net [83.223.95.28]) (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 mailout1.hostsharing.net (Postfix) with ESMTPS id 0B87C101A7220; Sat, 3 Aug 2019 12:35:57 +0200 (CEST) Received: from localhost (unknown [89.246.108.87]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by h08.hostsharing.net (Postfix) with ESMTPSA id B9C94618F189; Sat, 3 Aug 2019 12:35:56 +0200 (CEST) X-Mailbox-Line: From 69faaeb305582ab7dca65fa08635edfa1a39b3fa Mon Sep 17 00:00:00 2001 Message-Id: <69faaeb305582ab7dca65fa08635edfa1a39b3fa.1564825752.git.lukas@wunner.de> In-Reply-To: References: From: Lukas Wunner Date: Sat, 3 Aug 2019 12:10:00 +0200 Subject: [PATCH 03/10] spi: Guarantee cacheline alignment of driver-private data MIME-Version: 1.0 To: Mark Brown , Vinod Koul , Stefan Wahren , linux-spi@vger.kernel.org, dmaengine@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com Cc: Eric Anholt , Nuno Sa , Martin Sperl , Noralf Tronnes , Robert Jarzmik , Florian Kauer , Florian Fainelli , Ray Jui , Scott Branden Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP __spi_alloc_controller() uses a single allocation to accommodate struct spi_controller and the driver-private data, but places the latter behind the former. This order does not guarantee cacheline alignment of the driver-private data. It does guarantee cacheline alignment of struct spi_controller but the structure doesn't make any use of that property. Reverse the order. A forthcoming commit leverages this to grant DMA access to driver-private data of the BCM2835 SPI master. An alternative approach would be to round up struct spi_controller to cacheline size, at the expense of some wasted memory. Tested-by: Nuno Sá Signed-off-by: Lukas Wunner --- drivers/spi/spi.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 8e83c9567353..8f692f657690 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -2071,9 +2071,11 @@ static inline void acpi_register_spi_devices(struct spi_controller *ctlr) {} static void spi_controller_release(struct device *dev) { struct spi_controller *ctlr; + void *devdata; ctlr = container_of(dev, struct spi_controller, dev); - kfree(ctlr); + devdata = spi_controller_get_devdata(ctlr); + kfree(devdata); } static struct class spi_master_class = { @@ -2187,8 +2189,10 @@ extern struct class spi_slave_class; /* dummy */ * __spi_alloc_controller - allocate an SPI master or slave controller * @dev: the controller, possibly using the platform_bus * @size: how much zeroed driver-private data to allocate; the pointer to this - * memory is in the driver_data field of the returned device, - * accessible with spi_controller_get_devdata(). + * memory is in the driver_data field of the returned device, accessible + * with spi_controller_get_devdata(); the memory is cacheline aligned; + * drivers granting DMA access to portions of their private data need to + * round up @size using ALIGN(size, dma_get_cache_alignment()). * @slave: flag indicating whether to allocate an SPI master (false) or SPI * slave (true) controller * Context: can sleep @@ -2210,14 +2214,16 @@ struct spi_controller *__spi_alloc_controller(struct device *dev, unsigned int size, bool slave) { struct spi_controller *ctlr; + void *devdata; if (!dev) return NULL; - ctlr = kzalloc(size + sizeof(*ctlr), GFP_KERNEL); - if (!ctlr) + devdata = kzalloc(size + sizeof(*ctlr), GFP_KERNEL); + if (!devdata) return NULL; + ctlr = devdata + size; device_initialize(&ctlr->dev); ctlr->bus_num = -1; ctlr->num_chipselect = 1; @@ -2228,7 +2234,7 @@ struct spi_controller *__spi_alloc_controller(struct device *dev, ctlr->dev.class = &spi_master_class; ctlr->dev.parent = dev; pm_suspend_ignore_children(&ctlr->dev, true); - spi_controller_set_devdata(ctlr, &ctlr[1]); + spi_controller_set_devdata(ctlr, devdata); return ctlr; }