From patchwork Fri Jun 16 14:12:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miquel Raynal X-Patchwork-Id: 13282851 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 20A28EB64DA for ; Fri, 16 Jun 2023 14:12:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version: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:In-Reply-To:References: List-Owner; bh=4z7DkioVIploUUc7i5JCk7rPNdAyX2LG2UA/9ON1ARI=; b=kzrnysgP26h+JK soxCrzS0Lvanxhqf5enrto0lGfrCsuPuO8ZOCaSXtMyWMaf9UHjJMyyLsOXfZb2J5ztl50QXeJNMk NTmkeW+21sBz7mwDfN4HlAvudgcydPCalkT0srKg5n9xmCq88MzjwwQZHdjcxQtaiN2/pLG/95Y0p 7jxiEuSMrSMmnvvzFnsQPC4FLg3tdSmPvJ7v3yaMqN1zejiqNqK54kcVDO4YH0txqm6y+VccsdbB/ RGeDPetkDbX5LD9buamq7Cv+qguNU3aIB4SDnTqXW5dR2CyCKNJQgmPOqJt3CawURRdC4EvTMLdcw njgY2LaRl1pHm8Kz9tkQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qAABn-000mBJ-34; Fri, 16 Jun 2023 14:12:35 +0000 Received: from relay6-d.mail.gandi.net ([2001:4b98:dc4:8::226]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qAABk-000mA9-1p for linux-arm-kernel@lists.infradead.org; Fri, 16 Jun 2023 14:12:34 +0000 X-GND-Sasl: miquel.raynal@bootlin.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1686924748; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=LzITj3fzmJe1KpGO3Dwg9TUIzW0oQVwYevSz6N4g/0k=; b=g5y1IPprHUUvFK4Ues8ekTBs+fafE7VSxQYrLRE0dSVcqKQEoR8fz/hjuwY7AXw2fCaSye RD6C4zr9VeiVa/7Iskc/tyn1dZaStXVitj4p/31ruiFQqUGFcHA7XO37zentIY0kOKQtIP 2WM+3Sfu8TjFC5bG+VZFdYBHmCq+ebqrKKA+t299sNQKrVAZ+zllsZhPjYIPjxmPRUCsux qSuQihNotheXogEmik07QDugPWDrxX2hQq+1ck1fCy4PpSIRR9UXyqvZu2hNK7f+z5hgiL M3M1WsVPuzJaNHOVdLoMdkSmxIfk8agJSrESjF1BtnlRWRe3uoKD1Ccn/84V6A== X-GND-Sasl: miquel.raynal@bootlin.com X-GND-Sasl: miquel.raynal@bootlin.com X-GND-Sasl: miquel.raynal@bootlin.com X-GND-Sasl: miquel.raynal@bootlin.com X-GND-Sasl: miquel.raynal@bootlin.com X-GND-Sasl: miquel.raynal@bootlin.com X-GND-Sasl: miquel.raynal@bootlin.com X-GND-Sasl: miquel.raynal@bootlin.com Received: by mail.gandi.net (Postfix) with ESMTPSA id 0FEF6C0018; Fri, 16 Jun 2023 14:12:25 +0000 (UTC) From: Miquel Raynal To: Tudor Ambarus , Mark Brown , Subject: [PATCH] spi: atmel: Prevent false timeouts on long transfers Date: Fri, 16 Jun 2023 16:12:25 +0200 Message-Id: <20230616141225.2790073-1-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230616_071232_923302_AF538203 X-CRM114-Status: GOOD ( 14.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexandre Belloni , Thomas Petazzoni , Miquel Raynal , Claudiu Beznea , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org A slow SPI bus clocks at ~20MHz, which means it would transfer about 2500 bytes per second with a single data line. Big transfers, like when dealing with flashes can easily reach a few MiB. The current DMA timeout is set to 1 second, which means any working transfer of about 4MiB will always be cancelled. With the above derivations, on a slow bus, we can assume every byte will take at most 0.4ms. Said otherwise, we could add 4ms to the 1-second timeout delay every 10kiB. On a 4MiB transfer, it would bring the timeout delay up to 2.6s which still seems rather acceptable for a timeout. The consequence of this is that long transfers might be allowed, which hence requires the need to interrupt the transfer if wanted by the user. We can hence switch to the _interruptible variant of wait_for_completion. This leads to a little bit more handling to also handle the interrupted case but looks really acceptable overall. While at it, we drop the useless, noisy and redundant WARN_ON() call. Signed-off-by: Miquel Raynal --- drivers/spi/spi-atmel.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c index c4f22d50dba5..00f269f955ef 100644 --- a/drivers/spi/spi-atmel.c +++ b/drivers/spi/spi-atmel.c @@ -233,7 +233,8 @@ */ #define DMA_MIN_BYTES 16 -#define SPI_DMA_TIMEOUT (msecs_to_jiffies(1000)) +#define SPI_DMA_MIN_TIMEOUT (msecs_to_jiffies(1000)) +#define SPI_DMA_TIMEOUT_PER_10K (msecs_to_jiffies(4)) #define AUTOSUSPEND_TIMEOUT 2000 @@ -1280,6 +1281,7 @@ static int atmel_spi_one_transfer(struct spi_master *master, int timeout; int ret; unsigned long dma_timeout; + long ret_timeout; as = spi_master_get_devdata(master); @@ -1308,6 +1310,11 @@ static int atmel_spi_one_transfer(struct spi_master *master, as->current_remaining_bytes = xfer->len; while (as->current_remaining_bytes) { reinit_completion(&as->xfer_completion); + /* If transfer is bigger than 10kiB, enlarge the timeout */ + dma_timeout = SPI_DMA_MIN_TIMEOUT; + if (as->current_remaining_bytes > 0x2800) + dma_timeout += (as->current_remaining_bytes / 0x2800) * + SPI_DMA_TIMEOUT_PER_10K; if (as->use_pdc) { atmel_spi_lock(as); @@ -1333,11 +1340,12 @@ static int atmel_spi_one_transfer(struct spi_master *master, atmel_spi_unlock(as); } - dma_timeout = wait_for_completion_timeout(&as->xfer_completion, - SPI_DMA_TIMEOUT); - if (WARN_ON(dma_timeout == 0)) { - dev_err(&spi->dev, "spi transfer timeout\n"); - as->done_status = -EIO; + ret_timeout = wait_for_completion_interruptible_timeout(&as->xfer_completion, + dma_timeout); + if (ret_timeout <= 0) { + dev_err(&spi->dev, "spi transfer %s\n", + !ret_timeout ? "timeout" : "canceled"); + as->done_status = ret_timeout < 0 ? ret_timeout : -EIO; } if (as->done_status)