From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91109C10F03 for ; Tue, 23 Apr 2019 20:16:49 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4CEED208E4 for ; Tue, 23 Apr 2019 20:16:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jrwNfojt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4CEED208E4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=martin.sperl.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: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=MehkxGccS0dHZMNmfJGIIF3ks5S1fvM/kyF1gPgyoZM=; b=jrwNfojtWe3iUWxsk1A1luGRD+ VGf2LF46YAvxLMa082TtBbvN9XP4n+quhog8EZbUtWyp5oT/gPbdRTc5mWUL7WP1SIht58Ox69mwW WgbZeGX8Vh+Iuje2UtOr6nyzo+PaH5QKAmLLI5xhXdCRB17Q4WDjhftSRV4P5kengyEY54gYNpIxe W7t3z3+a3wq84i9dDrPQEI+68nev+mOydm0PiIJO1V4A1Gm5TkXUMhRncC2VvpPupmh+q0oRBvHbU oLI4TX7gGczYqxYnino631c/2Uf6/IH/45drR/aRvDcgFoQlC98cP7ZyulkPZG4UNtG1TkC0iPoDe iBIzyBew==; 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 1hJ1qL-0000iC-90; Tue, 23 Apr 2019 20:16:41 +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 1hJ1pi-00086p-Hq; Tue, 23 Apr 2019 20:16:04 +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 7763606; Tue, 23 Apr 2019 20:15:33 +0000 From: kernel@martin.sperl.org To: Mark Brown , Eric Anholt , Stefan Wahren , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH V2 4/6] spi: bcm2835: make the polling duration limits configurable Date: Tue, 23 Apr 2019 20:15:11 +0000 Message-Id: <20190423201513.8073-5-kernel@martin.sperl.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190423201513.8073-1-kernel@martin.sperl.org> References: <20190423201513.8073-1-kernel@martin.sperl.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190423_131602_770729_1A5A58C5 X-CRM114-Status: UNSURE ( 9.63 ) 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 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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/...) This replicates similar code found in spi-bcm2835aux. Signed-off-by: Martin Sperl Changelog: V1 -> V2: applied feedback by Stefan Wahren reorganized patchset added extra rational, descriptions --- drivers/spi/spi-bcm2835.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 3140d952c03a..2d702db8689c 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -73,14 +73,18 @@ #define BCM2835_SPI_FIFO_SIZE 64 #define BCM2835_SPI_FIFO_SIZE_3_4 48 -#define BCM2835_SPI_POLLING_LIMIT_US 30 -#define BCM2835_SPI_POLLING_JIFFIES 2 #define BCM2835_SPI_DMA_MIN_LENGTH 96 #define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \ | SPI_NO_CS | SPI_3WIRE) #define DRV_NAME "spi-bcm2835" +/* 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"); + /** * struct bcm2835_spi - BCM2835 SPI controller * @regs: base address of register map @@ -739,8 +743,8 @@ static int bcm2835_spi_transfer_one_poll(struct spi_master *master, */ bcm2835_wr_fifo_blind(bs, BCM2835_SPI_FIFO_SIZE); - /* set the timeout */ - timeout = jiffies + BCM2835_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) { @@ -775,8 +779,8 @@ static int bcm2835_spi_transfer_one(struct spi_master *master, struct spi_transfer *tfr) { struct bcm2835_spi *bs = spi_master_get_devdata(master); - unsigned long spi_hz, clk_hz, cdiv; - unsigned long spi_used_hz; + unsigned long spi_hz, clk_hz, cdiv, spi_used_hz; + unsigned long hz_per_byte, byte_limit; u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); /* set clock */ @@ -823,9 +827,11 @@ static int bcm2835_spi_transfer_one(struct spi_master *master, * per byte per polling limit. E.g., we can transfer 1 byte in 30 us * per 300,000 Hz of bus clock. */ -#define HZ_PER_BYTE ((9 * 1000000) / BCM2835_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 bcm2835_spi_transfer_one_poll(master, spi, tfr, cs); /* run in dma mode if conditions are right -- 2.11.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel