From patchwork Sun Mar 24 17:50:02 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Martin Sperl X-Patchwork-Id: 10867649 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 E6FD3922 for ; Sun, 24 Mar 2019 17:53:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D3C8A2914B for ; Sun, 24 Mar 2019 17:53:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C2E6228FBD; Sun, 24 Mar 2019 17:53:04 +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 52F1728FBD for ; Sun, 24 Mar 2019 17:53:04 +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=Kgh0tAyYWQtIL3/nF0xLDgyCzGKxM77EsvxRK1efTIs=; b=cvHDdQ5+N2XqfD mQKfvcLfqRlRUsfjNBzX0ViA6B0QnxOKQq1YekD+VEvu0JOdYEjqbiQ0TRcZ5dA9Ls+SgfBpd5Bjb fjwZgd/Y72TyOfp26b+SRC5NT+V0hckeol1KmIL3JuYT5gvSSh1xDNfXDmd9NgAbpjF3mW/wsAH9l 7MXtpbBeUP+aYHP6Qoydc6/XCFb+ERhtUOv5BaG239Hwx0WiRgyCoHA//7DIKjJSwEZ/HeEa8q1zO syiKb6NB+HSSU0Z1wmMZkh5VDbPYJd43K/pZaMK3OAcjade2CNJaYGZapDpgCxl+oBoOzkAhWlimz VPyKHC7KTi/lSYBWojBg==; 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 1h87It-0001xR-2b; Sun, 24 Mar 2019 17:53:03 +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 1h87HU-0007UD-HF; Sun, 24 Mar 2019 17:52:03 +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 7759432; Sun, 24 Mar 2019 17:50:11 +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 V2 9/9] spi: bcm2835aux: make the polling duration limits configurable Date: Sun, 24 Mar 2019 17:50:02 +0000 Message-Id: <20190324175002.28969-10-kernel@martin.sperl.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190324175002.28969-1-kernel@martin.sperl.org> References: <20190324175002.28969-1-kernel@martin.sperl.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190324_105137_451506_0C2315E8 X-CRM114-Status: GOOD ( 11.15 ) 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: V1 -> V2: remove the dependency on a different patchset focused on making cs_change delay configurable --- 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 d2b58060b333..df065108122b 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\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; @@ -325,8 +327,8 @@ 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) { @@ -356,8 +358,8 @@ 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 * @@ -401,14 +403,15 @@ 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,