From patchwork Thu Aug 28 06:53:45 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Simon Horman X-Patchwork-Id: 4798751 Return-Path: X-Original-To: patchwork-ltsi-dev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 25F01C0338 for ; Thu, 28 Aug 2014 08:24:47 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 49D592012E for ; Thu, 28 Aug 2014 08:24:46 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8D9A8200E8 for ; Thu, 28 Aug 2014 08:24:43 +0000 (UTC) Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id B39DB1458; Thu, 28 Aug 2014 07:33:08 +0000 (UTC) X-Original-To: ltsi-dev@lists.linuxfoundation.org Delivered-To: ltsi-dev@mail.linuxfoundation.org Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 09E8D1401 for ; Thu, 28 Aug 2014 07:33:06 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from kirsty.vergenet.net (kirsty.vergenet.net [202.4.237.240]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id 915B31F88A for ; Thu, 28 Aug 2014 07:33:05 +0000 (UTC) Received: from ayumi.isobedori.kobe.vergenet.net (p4222-ipbfp1605kobeminato.hyogo.ocn.ne.jp [114.154.95.222]) by kirsty.vergenet.net (Postfix) with ESMTP id 9603C2671A8; Thu, 28 Aug 2014 17:07:41 +1000 (EST) Received: by ayumi.isobedori.kobe.vergenet.net (Postfix, from userid 7100) id 1FB73EDE709; Thu, 28 Aug 2014 16:07:39 +0900 (JST) From: Simon Horman To: ltsi-dev@lists.linuxfoundation.org Date: Thu, 28 Aug 2014 15:53:45 +0900 Message-Id: <1409209620-24487-100-git-send-email-horms+renesas@verge.net.au> X-Mailer: git-send-email 2.0.1 In-Reply-To: <1409209620-24487-1-git-send-email-horms+renesas@verge.net.au> References: <1409209620-24487-1-git-send-email-horms+renesas@verge.net.au> X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org Cc: Magnus Damm Subject: [LTSI-dev] [PATCH LTSI-3.14 099/894] spi: rspi: Only enable interrupts when there's a need to wait X-BeenThere: ltsi-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: "A list to discuss patches, development, and other things related to the LTSI project" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: ltsi-dev-bounces@lists.linuxfoundation.org Errors-To: ltsi-dev-bounces@lists.linuxfoundation.org X-Virus-Scanned: ClamAV using ClamSMTP From: Geert Uytterhoeven rspi_wait_for_interrupt() unconditionally enables interrupts, even when the wait condition is already satisfied. This causes a high interrupt load (2 interrupts/byte for full-duplex Single SPI transfers, 1 interrupt/byte for RSPI with TX Only mode, or QSPI in unidirectional Dual or Quad Transfer mode). Change this to return immediately when the wait condition is satisfied. This dramatically reduces the interrupt load, especially in high-speed Quad Transfer mode, and increases transfer speed, as no interrupts need to be handled when there's space available in the output FIFO, or data available in the input FIFO. Benchmark results for QSPI on r8a7791 while reading 1 MiB from 30 MHz SPI FLASH on the Koelsch development board: Before: Single SPI Dual SPI Quad SPI Interrupts: 2096856 1048592 1048594 Mbps: 0.9 1.6 1.6 After: Single SPI Dual SPI Quad SPI Interrupts: 1048569 21295 8 Mbps: 0.7 10.8 12.9 I don't know why Single SPI slowed down a bit. I've also verified functionality for RSPI-RZ on r7s72100, but don't have benchmark results as there's no SPI FLASH connected to RSPI on the Genmai development board. Unlike RSPI and QSPI, RSPI-RZ has separate interrupts for RX and TX, which shows that Single SPI transfers now generate (mostly) RX interrupts, as expected. Signed-off-by: Geert Uytterhoeven Signed-off-by: Mark Brown (cherry picked from commit 5dd1ad23af689591d70be06ee6efcc57d1ec2d16) Signed-off-by: Simon Horman --- drivers/spi/spi-rspi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c index e5cfc3d..0452888 100644 --- a/drivers/spi/spi-rspi.c +++ b/drivers/spi/spi-rspi.c @@ -391,6 +391,9 @@ static int rspi_wait_for_interrupt(struct rspi_data *rspi, u8 wait_mask, int ret; rspi->spsr = rspi_read8(rspi, RSPI_SPSR); + if (rspi->spsr & wait_mask) + return 0; + rspi_enable_irq(rspi, enable_bit); ret = wait_event_timeout(rspi->wait, rspi->spsr & wait_mask, HZ); if (ret == 0 && !(rspi->spsr & wait_mask))