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authorCharanya Venkatraman <charanya@codeaurora.org>2016-06-07 15:58:41 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-25 10:23:54 -0700
commit002eb41f303e007011aecba25ea6de25a4ed475f (patch)
treeba3f7e89dc3570126fa55b458ecc8fe73a92654a
parente4276ff8a08116f22589b4f52974cf82cd3207db (diff)
downloadtalos-obmc-linux-002eb41f303e007011aecba25ea6de25a4ed475f.tar.gz
talos-obmc-linux-002eb41f303e007011aecba25ea6de25a4ed475f.zip
tty:serial:msm:Do not restore Rx interrupts in DMA
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> Acked-by: Andy Gross <andy.gross@linaro.org> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/tty/serial/msm_serial.c4
1 files changed, 0 insertions, 4 deletions
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 88af5a3d21dd..d0384d4cccb1 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -557,10 +557,6 @@ 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);
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