serial: 8250_lpss: Configure DMA also w/o DMA filter

commit 1bfcbe5805d0cfc83c3544dcd01e0a282c1f6790 upstream.

If the platform doesn't use DMA device filter (as is the case with
Elkhart Lake), whole lpss8250_dma_setup() setup is skipped. This
results in skipping also *_maxburst setup which is undesirable.
Refactor lpss8250_dma_setup() to configure DMA even if filter is not
setup.

Cc: stable <stable@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221108121952.5497-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
index 49ae73f..faa4251 100644 (file)
--- a/drivers/tty/serial/8250/8250_lpss.c
+++ b/drivers/tty/serial/8250/8250_lpss.c
@@ -278,8 +278,13 @@ static int lpss8250_dma_setup(struct lpss8250 *lpss, struct uart_8250_port *port
        struct dw_dma_slave *rx_param, *tx_param;
        struct device *dev = port->port.dev;
 
-       if (!lpss->dma_param.dma_dev)
+       if (!lpss->dma_param.dma_dev) {
+               dma = port->dma;
+               if (dma)
+                       goto out_configuration_only;
+
                return 0;
+       }
 
        rx_param = devm_kzalloc(dev, sizeof(*rx_param), GFP_KERNEL);
        if (!rx_param)
@@ -290,16 +295,18 @@ static int lpss8250_dma_setup(struct lpss8250 *lpss, struct uart_8250_port *port
                return -ENOMEM;
 
        *rx_param = lpss->dma_param;
-       dma->rxconf.src_maxburst = lpss->dma_maxburst;
-
        *tx_param = lpss->dma_param;
-       dma->txconf.dst_maxburst = lpss->dma_maxburst;
 
        dma->fn = lpss8250_dma_filter;
        dma->rx_param = rx_param;
        dma->tx_param = tx_param;
 
        port->dma = dma;
+
+out_configuration_only:
+       dma->rxconf.src_maxburst = lpss->dma_maxburst;
+       dma->txconf.dst_maxburst = lpss->dma_maxburst;
+
        return 0;
 }