From patchwork Mon Jan 27 13:21:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Ujfalusi X-Patchwork-Id: 11352625 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 014AC924 for ; Mon, 27 Jan 2020 13:20:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA95D22522 for ; Mon, 27 Jan 2020 13:20:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="hbfAPkgr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726443AbgA0NUf (ORCPT ); Mon, 27 Jan 2020 08:20:35 -0500 Received: from fllv0015.ext.ti.com ([198.47.19.141]:32878 "EHLO fllv0015.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725907AbgA0NUe (ORCPT ); Mon, 27 Jan 2020 08:20:34 -0500 Received: from fllv0035.itg.ti.com ([10.64.41.0]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 00RDKUlr010359; Mon, 27 Jan 2020 07:20:30 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1580131230; bh=WZX9hw0vJrnRoLJJ8uDBMetTVF4QumnXa6t16GcKdt4=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=hbfAPkgrrpN9SLEPmiffpjHUzSUK4ArBQUM1sN9Eq8rEC00W9z6w3lYLME7VbXlS8 5PzM3YHFazw6d8dzul2Rc9/rjRlQg00liI33lukyPDYTlz4LPi9HRAzPbIgFnGCrT8 ysmw7j+ziWcNavSrqiIImPbeHf+Zei8Q2aPc0niw= Received: from DLEE113.ent.ti.com (dlee113.ent.ti.com [157.170.170.24]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTP id 00RDKUiS118170; Mon, 27 Jan 2020 07:20:30 -0600 Received: from DLEE111.ent.ti.com (157.170.170.22) by DLEE113.ent.ti.com (157.170.170.24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3; Mon, 27 Jan 2020 07:20:29 -0600 Received: from fllv0039.itg.ti.com (10.64.41.19) by DLEE111.ent.ti.com (157.170.170.22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3 via Frontend Transport; Mon, 27 Jan 2020 07:20:29 -0600 Received: from feketebors.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0039.itg.ti.com (8.15.2/8.15.2) with ESMTP id 00RDKPa3020427; Mon, 27 Jan 2020 07:20:27 -0600 From: Peter Ujfalusi To: CC: , , , , Subject: [PATCH for-next 1/4] dmaengine: ti: k3-udma: Use ktime/usleep_range based TX completion check Date: Mon, 27 Jan 2020 15:21:08 +0200 Message-ID: <20200127132111.20464-2-peter.ujfalusi@ti.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200127132111.20464-1-peter.ujfalusi@ti.com> References: <20200127132111.20464-1-peter.ujfalusi@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org From: Vignesh Raghavendra In some cases (McSPI for example) the jiffie and delayed_work based workaround can cause big throughput drop. Switch to use ktime/usleep_range based implementation to be able to sustain speed for PDMA based peripherals. Signed-off-by: Vignesh Raghavendra Signed-off-by: Peter Ujfalusi --- drivers/dma/ti/k3-udma.c | 80 ++++++++++++++++++++++++++-------------- 1 file changed, 53 insertions(+), 27 deletions(-) diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c index ea79c2df28e0..fb59c869a6a7 100644 --- a/drivers/dma/ti/k3-udma.c +++ b/drivers/dma/ti/k3-udma.c @@ -5,6 +5,7 @@ */ #include +#include #include #include #include @@ -169,7 +170,7 @@ enum udma_chan_state { struct udma_tx_drain { struct delayed_work work; - unsigned long jiffie; + ktime_t tstamp; u32 residue; }; @@ -946,9 +947,10 @@ static bool udma_is_desc_really_done(struct udma_chan *uc, struct udma_desc *d) peer_bcnt = udma_tchanrt_read(uc->tchan, UDMA_TCHAN_RT_PEER_BCNT_REG); bcnt = udma_tchanrt_read(uc->tchan, UDMA_TCHAN_RT_BCNT_REG); + /* Transfer is incomplete, store current residue and time stamp */ if (peer_bcnt < bcnt) { uc->tx_drain.residue = bcnt - peer_bcnt; - uc->tx_drain.jiffie = jiffies; + uc->tx_drain.tstamp = ktime_get(); return false; } @@ -961,35 +963,59 @@ static void udma_check_tx_completion(struct work_struct *work) tx_drain.work.work); bool desc_done = true; u32 residue_diff; - unsigned long jiffie_diff, delay; + ktime_t time_diff; + unsigned long delay; + + while (1) { + if (uc->desc) { + /* Get previous residue and time stamp */ + residue_diff = uc->tx_drain.residue; + time_diff = uc->tx_drain.tstamp; + /* + * Get current residue and time stamp or see if + * transfer is complete + */ + desc_done = udma_is_desc_really_done(uc, uc->desc); + } - if (uc->desc) { - residue_diff = uc->tx_drain.residue; - jiffie_diff = uc->tx_drain.jiffie; - desc_done = udma_is_desc_really_done(uc, uc->desc); - } - - if (!desc_done) { - jiffie_diff = uc->tx_drain.jiffie - jiffie_diff; - residue_diff -= uc->tx_drain.residue; - if (residue_diff) { - /* Try to guess when we should check next time */ - residue_diff /= jiffie_diff; - delay = uc->tx_drain.residue / residue_diff / 3; - if (jiffies_to_msecs(delay) < 5) - delay = 0; - } else { - /* No progress, check again in 1 second */ - delay = HZ; + if (!desc_done) { + /* + * Find the time delta and residue delta w.r.t + * previous poll + */ + time_diff = ktime_sub(uc->tx_drain.tstamp, + time_diff) + 1; + residue_diff -= uc->tx_drain.residue; + if (residue_diff) { + /* + * Try to guess when we should check + * next time by calculating rate at + * which data is being drained at the + * peer device + */ + delay = (time_diff / residue_diff) * + uc->tx_drain.residue; + } else { + /* No progress, check again in 1 second */ + schedule_delayed_work(&uc->tx_drain.work, HZ); + break; + } + + usleep_range(ktime_to_us(delay), + ktime_to_us(delay) + 10); + continue; } - schedule_delayed_work(&uc->tx_drain.work, delay); - } else if (uc->desc) { - struct udma_desc *d = uc->desc; + if (uc->desc) { + struct udma_desc *d = uc->desc; + + uc->bcnt += d->residue; + udma_start(uc); + vchan_cookie_complete(&d->vd); + break; + } - uc->bcnt += d->residue; - udma_start(uc); - vchan_cookie_complete(&d->vd); + break; } }