linux-kernel - [PATCH v1 1/1] serial: 8250_lpss: Enable DMA on Intel Elkhart Lake

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Date:   Wed, 21 Jul 2021 19:24:52 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>
Subject: [PATCH v1 1/1] serial: 8250_lpss: Enable DMA on Intel Elkhart Lake

PSE UARTs on Intel Elkhart Lake support DMA mode.
Enable DMA on these ports.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/tty/serial/8250/8250_lpss.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
index 4dee8a9e0c95..848d81e3838c 100644
--- a/drivers/tty/serial/8250/8250_lpss.c
+++ b/drivers/tty/serial/8250/8250_lpss.c
@@ -158,6 +158,16 @@ static int byt_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
 
 static int ehl_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
 {
+	struct uart_8250_dma *dma = &lpss->data.dma;
+	struct uart_8250_port *up = up_to_u8250p(port);
+
+	/*
+	 * This simply makes the checks in the 8250_port to try the DMA
+	 * channel request which in turn uses the magic of ACPI tables
+	 * parsing (see drivers/dma/acpi-dma.c for the details) and
+	 * matching with the registered General Purpose DMA controllers.
+	 */
+	up->dma = dma;
 	return 0;
 }
 
-- 
2.30.2