From patchwork Tue May 3 08:58:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 12835312 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 3DD06C433F5 for ; Tue, 3 May 2022 08:53:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232891AbiECI50 (ORCPT ); Tue, 3 May 2022 04:57:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230464AbiECI5Z (ORCPT ); Tue, 3 May 2022 04:57:25 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE18020BFD for ; Tue, 3 May 2022 01:53:53 -0700 (PDT) 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 5FAB7B81A56 for ; Tue, 3 May 2022 08:53:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 924AAC385B0; Tue, 3 May 2022 08:53:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651568031; bh=SALcPILQlJ3wwKAouKog/dFWpS5n452LpWj7no2Rshc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TEFyfYZrj2QcXLrcbDP8SdOfh2CouDjETpL5kbVYHx1CcK53Gw6CHqWwh9Ij9dPA3 iaXehU4f9ZpZ5xyUC3krZH3r54YtaAh9om47li9qW3MoDH19zNi7SJ8Yu+l8byplNc /OTFqDR4vXVNYpbsSGo8HJsOqScAc7ooPhyKnuVQghZtiq8fjWnSACj5jFy4fFVqyN T5+kpQfJNKDkIfg68wCwYGB9ZqEDI6AQkrPORSg9OoI5iD+1l4VHEvIpeEdXMCdlO1 RveiZ9nUzRovdKlJ8CiEEBBysmK/HPuSjCoPBb43mZ6CtRbfebuE/5/AXxcCuCtK5V 6yEIAKBs6E8Mw== From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Akinobu Mita , Alexandru Lazar , Alexandru Tachici , Antoniu Miclaus , Charles-Antoine Couret , Cosmin Tanislav , Cristian Pop , David Lechner , Ivan Mikhaylov , Jacopo Mondi , Jean-Baptiste Maneyrol , Lars-Peter Clausen , Marcelo Schmitt , =?utf-8?q?M=C3=A5rten_Lindahl?= , Matt Ranostay , Michael Hennerich , Michael Welling , Mugilraj Dhavachelvan , Navin Sankar Velliangiri , =?utf-8?q?Nuno_S=C3=A1?= , Paul Cercueil , Phil Reid , Puranjay Mohan , Ricardo Ribalda , Robert Jones , Rui Miguel Silva , Sean Nyekjaer , Tomas Melin , Tomislav Denis , =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Jonathan Cameron Subject: [PATCH 13/92] iio: adc: ad7476: Fix alignment for DMA safety Date: Tue, 3 May 2022 09:58:16 +0100 Message-Id: <20220503085935.1533814-14-jic23@kernel.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220503085935.1533814-1-jic23@kernel.org> References: <20220503085935.1533814-1-jic23@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Jonathan Cameron ____cacheline_aligned is an insufficient guarantee for non-coherent DMA on platforms with 128 byte cachelines above L1. Switch to the updated IIO_ALIGN definition. Update the comment to reflect that DMA safety 'may' require separate cachelines. Fixes tag is unlikely to be the actual introdution of the problem but is far enough back to cover any likely backporting. Fixes: 7a28fe3c93d6 ("staging:iio:ad7476: Squash driver into a single file.") Signed-off-by: Jonathan Cameron --- drivers/iio/adc/ad7476.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/iio/adc/ad7476.c b/drivers/iio/adc/ad7476.c index a1e8b32671cf..d02b1c801957 100644 --- a/drivers/iio/adc/ad7476.c +++ b/drivers/iio/adc/ad7476.c @@ -44,13 +44,12 @@ struct ad7476_state { struct spi_transfer xfer; struct spi_message msg; /* - * DMA (thus cache coherency maintenance) requires the + * DMA (thus cache coherency maintenance) may require the * transfer buffers to live in their own cache lines. * Make the buffer large enough for one 16 bit sample and one 64 bit * aligned 64 bit timestamp. */ - unsigned char data[ALIGN(2, sizeof(s64)) + sizeof(s64)] - ____cacheline_aligned; + unsigned char data[ALIGN(2, sizeof(s64)) + sizeof(s64)] __aligned(IIO_ALIGN); }; enum ad7476_supported_device_ids {