From patchwork Mon Oct 15 06:38:28 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vignesh Raghavendra X-Patchwork-Id: 10641195 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 D7CBD109C for ; Mon, 15 Oct 2018 06:40:41 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C3F2B2957A for ; Mon, 15 Oct 2018 06:40:41 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C21472958F; Mon, 15 Oct 2018 06:40:41 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 547AC2957A for ; Mon, 15 Oct 2018 06:40:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726711AbeJOOYX (ORCPT ); Mon, 15 Oct 2018 10:24:23 -0400 Received: from lelv0142.ext.ti.com ([198.47.23.249]:39370 "EHLO lelv0142.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726164AbeJOOYX (ORCPT ); Mon, 15 Oct 2018 10:24:23 -0400 Received: from dflxv15.itg.ti.com ([128.247.5.124]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id w9F6eRrJ039317; Mon, 15 Oct 2018 01:40:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1539585627; bh=2OxZ69j2xlDziQXmP+WBFk2wdY5rOJpPNrjFdeiQN5I=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=MFBV9R0MqgnWk6mlbO7UPKp4b6t71UtSomdAegpH1eOTR+D7r3XgAxO9baDR2RkFN mkP81vzec5bPqQwTbVR0GYKr0Jm9byNIgqBHJUFvOMf5om7MDm8lNiqKsRv3JMjWvG 9r+n1nLr+iPntibktC9BA9+GtDXAagnRmIV6XPig= Received: from DLEE115.ent.ti.com (dlee115.ent.ti.com [157.170.170.26]) by dflxv15.itg.ti.com (8.14.3/8.13.8) with ESMTP id w9F6eRKV005892; Mon, 15 Oct 2018 01:40:27 -0500 Received: from DLEE114.ent.ti.com (157.170.170.25) by DLEE115.ent.ti.com (157.170.170.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1466.3; Mon, 15 Oct 2018 01:40:27 -0500 Received: from dlep32.itg.ti.com (157.170.170.100) by DLEE114.ent.ti.com (157.170.170.25) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1466.3 via Frontend Transport; Mon, 15 Oct 2018 01:40:27 -0500 Received: from a0132425.india.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep32.itg.ti.com (8.14.3/8.13.8) with ESMTP id w9F6eH4P023129; Mon, 15 Oct 2018 01:40:25 -0500 From: Vignesh R To: Mark Brown CC: , , , Vignesh R , Sekhar Nori Subject: [PATCH 2/3] spi: omap2-mcspi: Set FIFO DMA trigger level to word length Date: Mon, 15 Oct 2018 12:08:28 +0530 Message-ID: <20181015063829.26978-3-vigneshr@ti.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181015063829.26978-1-vigneshr@ti.com> References: <20181015063829.26978-1-vigneshr@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP McSPI has 32 byte FIFO in Transmit-Receive mode. Current code tries to configuration FIFO watermark level for DMA trigger to be GCD of transfer length and max FIFO size which would mean trigger level may be set to 32 for transmit-receive mode if length is aligned. This does not work in case of SPI slave mode where FIFO always needs to have data ready whenever master starts the clock. With DMA trigger size of 32 there will be a small window during slave TX where DMA is still putting data into FIFO but master would have started clock for next byte, resulting in shifting out of stale data. Similarly, on Slave RX side there may be RX FIFO overflow Fix this by setting FIFO watermark for DMA trigger to word length. This means DMA is triggered as soon as FIFO has space for word length bytes and DMA would make sure FIFO is almost always full therefore improving FIFO occupancy in both master and slave mode. Signed-off-by: Vignesh R --- drivers/spi/spi-omap2-mcspi.c | 26 +++++++------------------- 1 file changed, 7 insertions(+), 19 deletions(-) diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index 985f00d8a964..88469bb22235 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -300,7 +300,7 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi, struct omap2_mcspi_cs *cs = spi->controller_state; struct omap2_mcspi *mcspi; unsigned int wcnt; - int max_fifo_depth, fifo_depth, bytes_per_word; + int max_fifo_depth, bytes_per_word; u32 chconf, xferlevel; mcspi = spi_master_get_devdata(master); @@ -316,10 +316,6 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi, else max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH; - fifo_depth = gcd(t->len, max_fifo_depth); - if (fifo_depth < 2 || fifo_depth % bytes_per_word != 0) - goto disable_fifo; - wcnt = t->len / bytes_per_word; if (wcnt > OMAP2_MCSPI_MAX_FIFOWCNT) goto disable_fifo; @@ -327,16 +323,17 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi, xferlevel = wcnt << 16; if (t->rx_buf != NULL) { chconf |= OMAP2_MCSPI_CHCONF_FFER; - xferlevel |= (fifo_depth - 1) << 8; + xferlevel |= (bytes_per_word - 1) << 8; } + if (t->tx_buf != NULL) { chconf |= OMAP2_MCSPI_CHCONF_FFET; - xferlevel |= fifo_depth - 1; + xferlevel |= bytes_per_word - 1; } mcspi_write_reg(master, OMAP2_MCSPI_XFERLEVEL, xferlevel); mcspi_write_chconf0(spi, chconf); - mcspi->fifo_depth = fifo_depth; + mcspi->fifo_depth = max_fifo_depth; return; } @@ -576,7 +573,6 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer) struct dma_slave_config cfg; enum dma_slave_buswidth width; unsigned es; - u32 burst; void __iomem *chstat_reg; void __iomem *irqstat_reg; int wait_res; @@ -596,22 +592,14 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer) } count = xfer->len; - burst = 1; - - if (mcspi->fifo_depth > 0) { - if (count > mcspi->fifo_depth) - burst = mcspi->fifo_depth / es; - else - burst = count / es; - } memset(&cfg, 0, sizeof(cfg)); cfg.src_addr = cs->phys + OMAP2_MCSPI_RX0; cfg.dst_addr = cs->phys + OMAP2_MCSPI_TX0; cfg.src_addr_width = width; cfg.dst_addr_width = width; - cfg.src_maxburst = burst; - cfg.dst_maxburst = burst; + cfg.src_maxburst = es; + cfg.dst_maxburst = es; rx = xfer->rx_buf; tx = xfer->tx_buf;