From patchwork Tue Jan 4 18:24:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Caron X-Patchwork-Id: 529978 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 B92CDC433F5 for ; Tue, 4 Jan 2022 18:26:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234742AbiADS0E (ORCPT ); Tue, 4 Jan 2022 13:26:04 -0500 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:51756 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S234693AbiADS0D (ORCPT ); Tue, 4 Jan 2022 13:26:03 -0500 Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.1.2/8.16.1.2) with ESMTP id 204FQG3J032620; Tue, 4 Jan 2022 19:25:49 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=selector1; bh=XMDrVIuvNH3fh4lFKIvoouUMZ8NmXg79A55JIgisRYA=; b=O5WJ2huiYSjhIacOMhYyx29Hx+JTOTC6s1yq0Umm2iyJlpC2q7y7UQHgoYvP5eImd/S4 0N/GnMcgWQaLLRtxY2VTZfvZabQn9Q7eUb9y3KX6/RgqOct+28lItlrzGGgi54ZTHdKS MetA6Oy+RA5FW1Da9HD9wO90dNqn7acpW8pjj+6gIH449h451oLac5n6HvzU32zIwmPF bdzrVMn269IoUcbrtFHwVC3gl5rlYF5MTgqujXAb1KkZWS65a1ssHHjvrNRJJF5dk4BH x8tAQuhAcZDMYpEv74iSEAUaBSgZntP0wCaj0NL3lrbkgAUicZEGd7C6BNfXhMsYjwHl Dg== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3dcagrc7wf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 04 Jan 2022 19:25:49 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 61F69100034; Tue, 4 Jan 2022 19:25:49 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag2node2.st.com [10.75.127.5]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 5A7DB24D5E6; Tue, 4 Jan 2022 19:25:49 +0100 (CET) Received: from localhost (10.75.127.44) by SFHDAG2NODE2.st.com (10.75.127.5) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Tue, 4 Jan 2022 19:25:48 +0100 From: Valentin Caron To: Greg Kroah-Hartman CC: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , Gerald Baeza , Erwan Le Ray , Valentin Caron , , , , Subject: [PATCH 1/4] serial: stm32: move tx dma terminate DMA to shutdown Date: Tue, 4 Jan 2022 19:24:42 +0100 Message-ID: <20220104182445.4195-2-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220104182445.4195-1-valentin.caron@foss.st.com> References: <20220104182445.4195-1-valentin.caron@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.44] X-ClientProxiedBy: SFHDAG2NODE2.st.com (10.75.127.5) To SFHDAG2NODE2.st.com (10.75.127.5) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-04_09,2022-01-04_01,2021-12-02_01 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Terminate DMA transaction and clear CR3_DMAT when shutdown is requested, instead of when remove is requested. If DMA transfer is not stopped in shutdown ops, driver will fail to start a new DMA transfer after next startup ops. Fixes: 3489187204eb ("serial: stm32: adding dma support") Signed-off-by: Erwan Le Ray Signed-off-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 3244e7f6818c..6cfc3bec6749 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -883,6 +883,11 @@ static void stm32_usart_shutdown(struct uart_port *port) u32 val, isr; int ret; + if (stm32_port->tx_dma_busy) { + dmaengine_terminate_async(stm32_port->tx_ch); + stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); + } + /* Disable modem control interrupts */ stm32_usart_disable_ms(port); @@ -1570,7 +1575,6 @@ static int stm32_usart_serial_remove(struct platform_device *pdev) writel_relaxed(cr3, port->membase + ofs->cr3); if (stm32_port->tx_ch) { - dmaengine_terminate_async(stm32_port->tx_ch); stm32_usart_of_dma_tx_remove(stm32_port, pdev); dma_release_channel(stm32_port->tx_ch); } From patchwork Tue Jan 4 18:24:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Caron X-Patchwork-Id: 530909 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 F2087C43217 for ; Tue, 4 Jan 2022 18:26:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236230AbiADS0I (ORCPT ); Tue, 4 Jan 2022 13:26:08 -0500 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:51774 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S234736AbiADS0F (ORCPT ); Tue, 4 Jan 2022 13:26:05 -0500 Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.1.2/8.16.1.2) with ESMTP id 204FUQ1F029263; Tue, 4 Jan 2022 19:25:50 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=selector1; bh=afe/Z9iYxJmYbWTSRofGvSsgFbbkGOpi70uPHEyEyKk=; b=XVFlWWoEHYknox8BShy7FVq1mDbzpf34PiHdz2+Gl3pTy/8Cg7QDhQsvQRvTxVfxlE0B LPl/nNpzaO2oB9MtjrqPAEhMbAMh0gMOtJzHGXyP/15JYIODO2YfpKpQvXUWt2GM1Ycn HNcRfq+epqFus8GmFm1gxFYMA/iovxf9e9Y1DP3bBH8AXJJZHFpknwPattBBecuDf3td mZBhOE98DP5OHPIOZVULWYTu+uYWNZhbTfB15bYKrvbO8wJhy0xrBPXs+UBqZRTpGIaS bExx1mTSgBzyRIkx3Aso5efd11P9+ltfyzAB2JYj1eYjMj85pB4o/NdvDkuoPvZgqrFR IA== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3dcagrc7wg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 04 Jan 2022 19:25:50 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 4885A10002A; Tue, 4 Jan 2022 19:25:50 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag2node2.st.com [10.75.127.5]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 3463424D5E6; Tue, 4 Jan 2022 19:25:50 +0100 (CET) Received: from localhost (10.75.127.45) by SFHDAG2NODE2.st.com (10.75.127.5) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Tue, 4 Jan 2022 19:25:49 +0100 From: Valentin Caron To: Greg Kroah-Hartman CC: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , Gerald Baeza , Erwan Le Ray , Valentin Caron , , , , Subject: [PATCH 2/4] serial: stm32: rework TX DMA state condition Date: Tue, 4 Jan 2022 19:24:43 +0100 Message-ID: <20220104182445.4195-3-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220104182445.4195-1-valentin.caron@foss.st.com> References: <20220104182445.4195-1-valentin.caron@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.45] X-ClientProxiedBy: SFHDAG2NODE2.st.com (10.75.127.5) To SFHDAG2NODE2.st.com (10.75.127.5) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-04_09,2022-01-04_01,2021-12-02_01 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org TX DMA state condition is handled by tx_dma_busy boolean. This boolean is set when dma descriptor is requested and reset when dma channel is stopped (dma_terminate). In stm32_usart_serial_remove(), stm32_usart_stop_tx() and stm32_usart_transmit_chars_dma() fallback error case, DMA channel is stopped but tx_dma_busy is not handled. Rework the driver by using two new functions to solve this issue: - stm32_usart_tx_dma_started return true if DMA TX have a descriptor. - stm32_usart_tx_dma_enabled return true if DMAT bit is set. stm32_usart_tx_dma_started uses tx_dma_busy flag to prevent dual DMA transaction at the same time. This flag is set when a DMA transaction begins and is unset when dmaengine_terminate_async function is called. A new DMA transaction cannot be created if this flag is set. Create a new function "stm32_usart_tx_dma_terminate" to be sure the flag is unset after each call of dmaengine_terminate_async. Signed-off-by: Erwan Le Ray Signed-off-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 66 +++++++++++++++++++++++--------- drivers/tty/serial/stm32-usart.h | 2 +- 2 files changed, 49 insertions(+), 19 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 6cfc3bec6749..52755a576bc2 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -365,6 +365,31 @@ static unsigned int stm32_usart_receive_chars(struct uart_port *port, bool force return size; } +static void stm32_usart_tx_dma_terminate(struct stm32_port *stm32_port) +{ + dmaengine_terminate_async(stm32_port->tx_ch); + stm32_port->tx_dma_busy = false; +} + +static bool stm32_usart_tx_dma_started(struct stm32_port *stm32_port) +{ + /* + * We cannot use the function "dmaengine_tx_status" to know the + * status of DMA. This function does not show if the "dma complete" + * callback of the DMA transaction has been called. So we prefer + * to use "tx_dma_busy" flag to prevent dual DMA transaction at the + * same time. + */ + return stm32_port->tx_dma_busy; +} + +static bool stm32_usart_tx_dma_enabled(struct stm32_port *stm32_port) +{ + const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + + return !!(readl_relaxed(stm32_port->port.membase + ofs->cr3) & USART_CR3_DMAT); +} + static void stm32_usart_tx_dma_complete(void *arg) { struct uart_port *port = arg; @@ -372,9 +397,8 @@ static void stm32_usart_tx_dma_complete(void *arg) const struct stm32_usart_offsets *ofs = &stm32port->info->ofs; unsigned long flags; - dmaengine_terminate_async(stm32port->tx_ch); stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); - stm32port->tx_dma_busy = false; + stm32_usart_tx_dma_terminate(stm32port); /* Let's see if we have pending data to send */ spin_lock_irqsave(&port->lock, flags); @@ -428,10 +452,8 @@ static void stm32_usart_transmit_chars_pio(struct uart_port *port) const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; struct circ_buf *xmit = &port->state->xmit; - if (stm32_port->tx_dma_busy) { + if (stm32_usart_tx_dma_enabled(stm32_port)) stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); - stm32_port->tx_dma_busy = false; - } while (!uart_circ_empty(xmit)) { /* Check that TDR is empty before filling FIFO */ @@ -457,10 +479,11 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) struct dma_async_tx_descriptor *desc = NULL; unsigned int count, i; - if (stm32port->tx_dma_busy) + if (stm32_usart_tx_dma_started(stm32port)) { + if (!stm32_usart_tx_dma_enabled(stm32port)) + stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAT); return; - - stm32port->tx_dma_busy = true; + } count = uart_circ_chars_pending(xmit); @@ -491,13 +514,21 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) if (!desc) goto fallback_err; + /* + * Set "tx_dma_busy" flag. This flag will be released when + * dmaengine_terminate_async will be called. This flag helps + * transmit_chars_dma not to start another DMA transaction + * if the callback of the previous is not yet called. + */ + stm32port->tx_dma_busy = true; + desc->callback = stm32_usart_tx_dma_complete; desc->callback_param = port; /* Push current DMA TX transaction in the pending queue */ if (dma_submit_error(dmaengine_submit(desc))) { /* dma no yet started, safe to free resources */ - dmaengine_terminate_async(stm32port->tx_ch); + stm32_usart_tx_dma_terminate(stm32port); goto fallback_err; } @@ -522,12 +553,13 @@ static void stm32_usart_transmit_chars(struct uart_port *port) struct circ_buf *xmit = &port->state->xmit; if (port->x_char) { - if (stm32_port->tx_dma_busy) + if (stm32_usart_tx_dma_started(stm32_port) && + stm32_usart_tx_dma_enabled(stm32_port)) stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); writel_relaxed(port->x_char, port->membase + ofs->tdr); port->x_char = 0; port->icount.tx++; - if (stm32_port->tx_dma_busy) + if (stm32_usart_tx_dma_started(stm32_port)) stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAT); return; } @@ -719,9 +751,8 @@ static void stm32_usart_flush_buffer(struct uart_port *port) const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; if (stm32_port->tx_ch) { - dmaengine_terminate_async(stm32_port->tx_ch); + stm32_usart_tx_dma_terminate(stm32_port); stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); - stm32_port->tx_dma_busy = false; } } @@ -883,10 +914,11 @@ static void stm32_usart_shutdown(struct uart_port *port) u32 val, isr; int ret; - if (stm32_port->tx_dma_busy) { - dmaengine_terminate_async(stm32_port->tx_ch); + if (stm32_usart_tx_dma_enabled(stm32_port)) stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); - } + + if (stm32_usart_tx_dma_started(stm32_port)) + stm32_usart_tx_dma_terminate(stm32_port); /* Disable modem control interrupts */ stm32_usart_disable_ms(port); @@ -1424,8 +1456,6 @@ static int stm32_usart_of_dma_tx_probe(struct stm32_port *stm32port, struct dma_slave_config config; int ret; - stm32port->tx_dma_busy = false; - stm32port->tx_buf = dma_alloc_coherent(dev, TX_BUF_L, &stm32port->tx_dma_buf, GFP_KERNEL); diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h index e23916bfbb60..feab952aec16 100644 --- a/drivers/tty/serial/stm32-usart.h +++ b/drivers/tty/serial/stm32-usart.h @@ -264,7 +264,7 @@ struct stm32_port { u32 cr1_irq; /* USART_CR1_RXNEIE or RTOIE */ u32 cr3_irq; /* USART_CR3_RXFTIE */ int last_res; - bool tx_dma_busy; /* dma tx busy */ + bool tx_dma_busy; /* dma tx transaction in progress */ bool throttled; /* port throttled */ bool hw_flow_control; bool swap; /* swap RX & TX pins */ From patchwork Tue Jan 4 18:24:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Caron X-Patchwork-Id: 529977 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 E25B1C433F5 for ; Tue, 4 Jan 2022 18:26:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232106AbiADS0H (ORCPT ); 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Tue, 04 Jan 2022 19:25:51 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id DE803100034; Tue, 4 Jan 2022 19:25:50 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag2node2.st.com [10.75.127.5]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id D868224D5E6; Tue, 4 Jan 2022 19:25:50 +0100 (CET) Received: from localhost (10.75.127.46) by SFHDAG2NODE2.st.com (10.75.127.5) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Tue, 4 Jan 2022 19:25:50 +0100 From: Valentin Caron To: Greg Kroah-Hartman CC: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , Gerald Baeza , Erwan Le Ray , Valentin Caron , , , , Subject: [PATCH 3/4] serial: stm32: fix flow control transfer in DMA mode Date: Tue, 4 Jan 2022 19:24:44 +0100 Message-ID: <20220104182445.4195-4-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220104182445.4195-1-valentin.caron@foss.st.com> References: <20220104182445.4195-1-valentin.caron@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG1NODE3.st.com (10.75.127.3) To SFHDAG2NODE2.st.com (10.75.127.5) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-04_09,2022-01-04_01,2021-12-02_01 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org If flow control is enabled, framework will call stop_tx to pause transfer and then call start_tx to resume transfer. Clear USART_CR3_DMAT bit in stop_tx ops to pause DMA transfer. Signed-off-by: Erwan Le Ray Signed-off-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 52755a576bc2..788e002688f2 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -707,8 +707,11 @@ static void stm32_usart_stop_tx(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); struct serial_rs485 *rs485conf = &port->rs485; + const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; stm32_usart_tx_interrupt_disable(port); + if (stm32_usart_tx_dma_started(stm32_port) && stm32_usart_tx_dma_enabled(stm32_port)) + stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); if (rs485conf->flags & SER_RS485_ENABLED) { if (rs485conf->flags & SER_RS485_RTS_ON_SEND) { From patchwork Tue Jan 4 18:24:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Caron X-Patchwork-Id: 530910 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 A754BC433EF for ; Tue, 4 Jan 2022 18:26:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236160AbiADS0H (ORCPT ); Tue, 4 Jan 2022 13:26:07 -0500 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:51772 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S234731AbiADS0F (ORCPT ); Tue, 4 Jan 2022 13:26:05 -0500 Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.1.2/8.16.1.2) with ESMTP id 204FQG3K032620; Tue, 4 Jan 2022 19:25:52 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=selector1; bh=5bcwS38T/HZMOjrZpC28q7ZFA6+/QWchHVmneYfJfeE=; b=FBoxAasqPWRIkJDBDUIsINVqVUj+cTanpvDBg8RjJyV39wzE22vpR7y9anOyjmJJyKlj tjUy4nSfoi9RMcQcKg2FHBB+ecrV74FKyM1gIINos4a/F/57T0zl46eqA2jrBeU+anN+ EssXoPmKRvJSIOHGui2Yv6L7DTJVqLUk5tKOj1cypF1fsbLkPz5CCA8YPnnWZwKe3btp 8kfyu0BPTUWhBvKVFYAFNIEaznm3u87eWi6nwJN9j074UU8ubt9zu/qgXLA8xO8sMzs1 j2z29MQxqFQNRr2wlSZ6chWPdgL0wmjvdSZ7ranfgz2a0EiegJsuk7oYrMtj5/Y+JL5P mA== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3dcagrc7wj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 04 Jan 2022 19:25:52 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id ABC8F10002A; Tue, 4 Jan 2022 19:25:51 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag2node2.st.com [10.75.127.5]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id A5D9E24D5E6; Tue, 4 Jan 2022 19:25:51 +0100 (CET) Received: from localhost (10.75.127.44) by SFHDAG2NODE2.st.com (10.75.127.5) with Microsoft SMTP Server (TLS) id 15.0.1497.26; Tue, 4 Jan 2022 19:25:50 +0100 From: Valentin Caron To: Greg Kroah-Hartman CC: Jiri Slaby , Maxime Coquelin , Alexandre Torgue , Gerald Baeza , Erwan Le Ray , Valentin Caron , , , , Subject: [PATCH 4/4] serial: stm32: correct loop for dma error handling Date: Tue, 4 Jan 2022 19:24:45 +0100 Message-ID: <20220104182445.4195-5-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220104182445.4195-1-valentin.caron@foss.st.com> References: <20220104182445.4195-1-valentin.caron@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.44] X-ClientProxiedBy: SFHDAG2NODE2.st.com (10.75.127.5) To SFHDAG2NODE2.st.com (10.75.127.5) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-04_09,2022-01-04_01,2021-12-02_01 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org In this error handling, "transmit_chars_dma" function will call "transmit_chars_pio" once per characters. But "transmit_chars_pio" will continue to send characters while xmit buffer is not empty. Remove this useless loop, one call is sufficient. Signed-off-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 788e002688f2..1f89ab0e49ac 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -477,7 +477,7 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) const struct stm32_usart_offsets *ofs = &stm32port->info->ofs; struct circ_buf *xmit = &port->state->xmit; struct dma_async_tx_descriptor *desc = NULL; - unsigned int count, i; + unsigned int count; if (stm32_usart_tx_dma_started(stm32port)) { if (!stm32_usart_tx_dma_enabled(stm32port)) @@ -542,8 +542,7 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) return; fallback_err: - for (i = count; i > 0; i--) - stm32_usart_transmit_chars_pio(port); + stm32_usart_transmit_chars_pio(port); } static void stm32_usart_transmit_chars(struct uart_port *port)