From patchwork Sat Mar 30 09:31:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Martin Sperl X-Patchwork-Id: 10878231 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 498ED1669 for ; Sat, 30 Mar 2019 09:33:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 32C9E290CC for ; Sat, 30 Mar 2019 09:33:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 271B9290D6; Sat, 30 Mar 2019 09:33:23 +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=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C04E3290CC for ; Sat, 30 Mar 2019 09:33:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=MKQJz2Bbi4Wo4iA/SJEqkqAuVZDpFC6rU9U8RbfmhHM=; b=q+uf0dNtQWzXzM DEwTmx1iXrn7u77Kdn85yn3z3yNQIa/oUsDo/wwQQplKnP7T/q6mcptB/Tnn9g6bBs2a39FFLLd9z kNsnwNb1QzonRCMFbu7tzDGFds00OkTtJ8ySS+bMNDwCLN2fPvwMIYclEhpSuUOYBWXq0V5Ut6raQ GVuOT7xyiti7Xnf6FrnhrAhixH3jrmOiVq7ehGCKqyWDc+MmGDhKTJRz9Z9h9ZoANyi+RGxicfpfw n/rV3jEJtQ1AZYuhUkC4rgMd6Sj4ggD0EuDmh9+fjZJwh7DzIhNSflNf1j0ZnZMdoPhZoK3BQhiV8 YZ6WeVw2mHX/XbrRmS4A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hAAMV-0003XL-NJ; Sat, 30 Mar 2019 09:33:15 +0000 Received: from 212-186-180-163.static.upcbusiness.at ([212.186.180.163] helo=cgate.sperl.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hAALG-0001PE-0V; Sat, 30 Mar 2019 09:32:02 +0000 Received: from hc1.intern.sperl.org (account martin@sperl.org [10.10.10.59] verified) by sperl.org (CommuniGate Pro SMTP 6.2.1 _community_) with ESMTPSA id 7760026; Sat, 30 Mar 2019 09:31:13 +0000 From: kernel@martin.sperl.org To: Mark Brown , Eric Anholt , Stefan Wahren , Hubert Denkmair , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH V3 9/9] spi: bcm2835aux: make the polling duration limits configurable Date: Sat, 30 Mar 2019 09:31:06 +0000 Message-Id: <20190330093106.20723-10-kernel@martin.sperl.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190330093106.20723-1-kernel@martin.sperl.org> References: <20190330093106.20723-1-kernel@martin.sperl.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190330_023158_912154_34191E3C X-CRM114-Status: UNSURE ( 9.94 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Martin Sperl Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Martin Sperl Under some circumstances the default 30 us polling limit is not optimal and may lead to long delays because we are waiting on an interrupt. with this patch we have the possibility to influence this policy. So make this limit (in us) configurable via a module parameters (but also modifyable via /sys/modules/...) Signed-off-by: Martin Sperl --- Changelog: V2 -> V3: clarified use case of polling_limit_us = 0 drivers/spi/spi-bcm2835aux.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) -- 2.11.0 diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index e7a4a161b78b..1a11b9131556 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -37,6 +37,12 @@ #include #include +/* define polling limits */ +unsigned int polling_limit_us = 30; +module_param(polling_limit_us, uint, 0664); +MODULE_PARM_DESC(polling_limit_us, + "time in us to run a transfer in polling mode - if zero no polling is used\n"); + /* * spi register defines * @@ -89,10 +95,6 @@ #define BCM2835_AUX_SPI_STAT_BUSY 0x00000040 #define BCM2835_AUX_SPI_STAT_BITCOUNT 0x0000003F -/* timeout values */ -#define BCM2835_AUX_SPI_POLLING_LIMIT_US 30 -#define BCM2835_AUX_SPI_POLLING_JIFFIES 2 - struct bcm2835aux_spi { void __iomem *regs; struct clk *clk; @@ -320,8 +322,8 @@ static int bcm2835aux_spi_transfer_one_poll(struct spi_master *master, bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]); bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]); - /* set the timeout */ - timeout = jiffies + BCM2835_AUX_SPI_POLLING_JIFFIES; + /* set the timeout to at least 2 jiffies */ + timeout = jiffies + 2 + HZ * polling_limit_us / 1000000; /* loop until finished the transfer */ while (bs->rx_len) { @@ -351,8 +353,8 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master, struct spi_transfer *tfr) { struct bcm2835aux_spi *bs = spi_master_get_devdata(master); - unsigned long spi_hz, clk_hz, speed; - unsigned long spi_used_hz; + unsigned long spi_hz, clk_hz, speed, spi_used_hz; + unsigned long hz_per_byte, byte_limit; /* calculate the registers to handle * @@ -396,14 +398,15 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master, * of Hz per byte per polling limit. E.g., we can transfer 1 byte in * 30 µs per 300,000 Hz of bus clock. */ -#define HZ_PER_BYTE ((9 * 1000000) / BCM2835_AUX_SPI_POLLING_LIMIT_US) + hz_per_byte = polling_limit_us ? (9 * 1000000) / polling_limit_us : 0; + byte_limit = hz_per_byte ? spi_used_hz / hz_per_byte : 1; + /* run in polling mode for short transfers */ - if (tfr->len < spi_used_hz / HZ_PER_BYTE) + if (tfr->len < byte_limit) return bcm2835aux_spi_transfer_one_poll(master, spi, tfr); /* run in interrupt mode for all others */ return bcm2835aux_spi_transfer_one_irq(master, spi, tfr); -#undef HZ_PER_BYTE } static int bcm2835aux_spi_prepare_message(struct spi_master *master,