From cc372a2739ee910390fd227f04a73c46e32e5b78 Mon Sep 17 00:00:00 2001 From: Kartik Rajput Date: Wed, 13 Nov 2024 14:56:29 +0530 Subject: [PATCH] serial: amba-pl011: Fix RX stall when DMA is used [ Upstream commit 2bcacc1c87acf9a8ebc17de18cb2b3cfeca547cf ] Function pl011_throttle_rx() calls pl011_stop_rx() to disable RX, which also disables the RX DMA by clearing the RXDMAE bit of the DMACR register. However, to properly unthrottle RX when DMA is used, the function pl011_unthrottle_rx() is expected to set the RXDMAE bit of the DMACR register, which it currently lacks. This causes RX to stall after the throttle API is called. Set RXDMAE bit in the DMACR register while unthrottling RX if RX DMA is used. Fixes: 211565b10099 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle") Cc: stable@vger.kernel.org Signed-off-by: Kartik Rajput Reviewed-by: Linus Walleij Link: https://lore.kernel.org/r/20241113092629.60226-1-kkartik@nvidia.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/amba-pl011.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index c95351d24f36..3eb718599413 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1837,6 +1837,11 @@ static void pl011_unthrottle_rx(struct uart_port *port) pl011_write(uap->im, uap, REG_IMSC); + if (uap->using_rx_dma) { + uap->dmacr |= UART011_RXDMAE; + pl011_write(uap->dmacr, uap, REG_DMACR); + } + uart_port_unlock_irqrestore(&uap->port, flags); }