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serial: amba-pl011: Fix RX stall when DMA is used

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[ 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: 211565b100 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle")
Cc: stable@vger.kernel.org
Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20241113092629.60226-1-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kartik Rajput
2024-11-13 14:56:29 +05:30
committed by Greg Kroah-Hartman
parent 5283338fcd
commit cc372a2739
1 changed files with 5 additions and 0 deletions
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5
drivers/tty/serial/amba-pl011.c
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@@ -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);
}