From: Charanya Venkatraman <charanya@codeaurora.org> To: agross@codeaurora.org, david.brown@linaro.org, andy.gross@linaro.org, gregkh@linuxfoundation.org Cc: jslaby@suse.com, linux-soc@vger.kernel.org, linux-serial@vger.kernel.org, sricharan@codeaurora.org, architt@codeaurora.org, linux-arm-msm@vger.kernel.org, ntelkar@codeaurora.org, galak@codeaurora.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, absahu@codeaurora.org, njaigane@codeaurora.org, Charanya Venkatraman <charanya@codeaurora.org> Subject: [PATCH v3] tty:serial:msm:Do not restore Rx interrupts in DMA Date: Tue, 7 Jun 2016 15:58:41 +0530 [thread overview] Message-ID: <1465295321-10506-1-git-send-email-charanya@codeaurora.org> (raw) In-Reply-To: <1462896580-11554-1> Avoid data corruption issues that result in CRC errors during file transfers over serial ports at higher baud rates. The current msm_serial driver masks the FIFO Rx interrupts in msm_start_rx_dma() since Rx FIFO interrupts are not required in DMA mode. However, msm_complete_rx_dma() re-enables the Rx FIFO interrupts which could cause RXSTALE event to be processed when a TXLEV interrupt occurs. The following is the sequence of events that could occur resulting in data corruption. msm_start_rx_dma -> msm_complete_rx_dma --> spin_unlock_irqrestore(&port->lock) --> msm_uart_irq()(For TXLEV interrupt) --> msm_handle_rx_dm() (Read from FIFO resulting in data corruption) The patch fixes the issue by not restoring the RXLEV and RXSTALE interrupts in msm_complete_rx_dma(). These interrupts are required only in FIFO mode. Signed-off-by: Charanya Venkatraman <charanya@codeaurora.org> --- Changes in v2: - Make commit message more clearer. Changes in v3: - Fix typos in commit message. drivers/tty/serial/msm_serial.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index b7d80bd..646aa3f 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -388,10 +388,6 @@ static void msm_complete_rx_dma(void *args) val &= ~dma->enable_bit; msm_write(port, val, UARTDM_DMEN); - /* Restore interrupts */ - msm_port->imr |= UART_IMR_RXLEV | UART_IMR_RXSTALE; - msm_write(port, msm_port->imr, UART_IMR); - if (msm_read(port, UART_SR) & UART_SR_OVERRUN) { port->icount.overrun++; tty_insert_flip_char(tport, 0, TTY_OVERRUN); -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
WARNING: multiple messages have this Message-ID (diff)
From: charanya@codeaurora.org (Charanya Venkatraman) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3] tty:serial:msm:Do not restore Rx interrupts in DMA Date: Tue, 7 Jun 2016 15:58:41 +0530 [thread overview] Message-ID: <1465295321-10506-1-git-send-email-charanya@codeaurora.org> (raw) In-Reply-To: <1462896580-11554-1> Avoid data corruption issues that result in CRC errors during file transfers over serial ports at higher baud rates. The current msm_serial driver masks the FIFO Rx interrupts in msm_start_rx_dma() since Rx FIFO interrupts are not required in DMA mode. However, msm_complete_rx_dma() re-enables the Rx FIFO interrupts which could cause RXSTALE event to be processed when a TXLEV interrupt occurs. The following is the sequence of events that could occur resulting in data corruption. msm_start_rx_dma -> msm_complete_rx_dma --> spin_unlock_irqrestore(&port->lock) --> msm_uart_irq()(For TXLEV interrupt) --> msm_handle_rx_dm() (Read from FIFO resulting in data corruption) The patch fixes the issue by not restoring the RXLEV and RXSTALE interrupts in msm_complete_rx_dma(). These interrupts are required only in FIFO mode. Signed-off-by: Charanya Venkatraman <charanya@codeaurora.org> --- Changes in v2: - Make commit message more clearer. Changes in v3: - Fix typos in commit message. drivers/tty/serial/msm_serial.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index b7d80bd..646aa3f 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -388,10 +388,6 @@ static void msm_complete_rx_dma(void *args) val &= ~dma->enable_bit; msm_write(port, val, UARTDM_DMEN); - /* Restore interrupts */ - msm_port->imr |= UART_IMR_RXLEV | UART_IMR_RXSTALE; - msm_write(port, msm_port->imr, UART_IMR); - if (msm_read(port, UART_SR) & UART_SR_OVERRUN) { port->icount.overrun++; tty_insert_flip_char(tport, 0, TTY_OVERRUN); -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2016-06-07 10:28 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <1462896580-11554-1> 2016-06-03 11:10 ` [PATCH v2] tty:serial:msm:Do not restore Rx interrupts in DMA Charanya Venkatraman 2016-06-03 11:10 ` Charanya Venkatraman 2016-06-03 15:47 ` Greg KH 2016-06-03 15:47 ` Greg KH 2016-06-07 10:28 ` Charanya Venkatraman [this message] 2016-06-07 10:28 ` [PATCH v3] " Charanya Venkatraman 2016-06-07 23:08 ` Stephen Boyd 2016-06-07 23:08 ` Stephen Boyd 2016-06-09 19:27 ` Andy Gross 2016-06-09 19:27 ` Andy Gross
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