From patchwork Tue Mar 7 16:44:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 661543 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34AD6C678D5 for ; Tue, 7 Mar 2023 16:47:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230353AbjCGQq4 (ORCPT ); Tue, 7 Mar 2023 11:46:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230117AbjCGQqg (ORCPT ); Tue, 7 Mar 2023 11:46:36 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A174196C32; Tue, 7 Mar 2023 08:43:39 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 6A36BB81928; Tue, 7 Mar 2023 16:43:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DBAAC433D2; Tue, 7 Mar 2023 16:43:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1678207417; bh=PAB2kcyznKkTzA0a1Jv3xHQl7lhPaWOJlLVm7w2vvWE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tRqzPZIfbElBEPP9RwjoCEqhk+gxtlXEDVAS2dhQxL9M9EDEpnm86M63FLMU36M5O 3cyzzxxaUhDqOi1krJ9nIlRANbgCU/Du3DdiYpLCPKpTbJfeSQaPdCKDQyJwHSTHQP SfpTMcbklQGdz4bScORVvcRZGA7dVoxpTr2vsGJN+1I9zA7eYzR8okM65CnbmY4JuR ujNT7S6mxvPV+ZYsYTbusn5WZfi3HBoAhXUVJy/hbJU6ix62tj307MrbE3V89TcLqY ZLvIftZh7nGe0q1QKIQL6PbRVmhhJYkAupeqNzr1QFhnt9+KuQxyAHlFwPwsWY1DBs om4GKEuU/BMYA== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1pZaQH-0003i7-45; Tue, 07 Mar 2023 17:44:21 +0100 From: Johan Hovold To: Greg Kroah-Hartman Cc: Bjorn Andersson , Andy Gross , Konrad Dybcio , Jiri Slaby , Bartosz Golaszewski , Douglas Anderson , Daniel Thompson , linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold Subject: [PATCH 3/4] serial: qcom-geni: fix mapping of empty DMA buffer Date: Tue, 7 Mar 2023 17:44:04 +0100 Message-Id: <20230307164405.14218-4-johan+linaro@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307164405.14218-1-johan+linaro@kernel.org> References: <20230307164405.14218-1-johan+linaro@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Make sure that there is data in the ring buffer before trying to set up a zero-length DMA transfer. This specifically fixes the following warning when unmapping the empty buffer on the sc8280xp-crd: WARNING: CPU: 0 PID: 138 at drivers/iommu/dma-iommu.c:1046 iommu_dma_unmap_page+0xbc/0xd8 ... Call trace: iommu_dma_unmap_page+0xbc/0xd8 dma_unmap_page_attrs+0x30/0x1c8 geni_se_tx_dma_unprep+0x28/0x38 qcom_geni_serial_isr+0x358/0x75c Fixes: 2aaa43c70778 ("tty: serial: qcom-geni-serial: add support for serial engine DMA") Cc: Bartosz Golaszewski Signed-off-by: Johan Hovold --- drivers/tty/serial/qcom_geni_serial.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index 2aa3872e6283..9871225b2f9b 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -631,6 +631,9 @@ static void qcom_geni_serial_start_tx_dma(struct uart_port *uport) if (port->tx_dma_addr) return; + if (uart_circ_empty(xmit)) + return; + xmit_size = uart_circ_chars_pending(xmit); if (xmit_size < WAKEUP_CHARS) uart_write_wakeup(uport);