serial: 8250_lpss: set PCI master only for private DMA

andy-shev · gregkh · commit 3f3a46951e02 · 2016-10-27T16:27:24.000+02:00
There is no need to set PCI bus mastering when device is not doing any DMA.
Though on Intel Quark DMA is a part of UART IP and thus shares same device in
Linux kernel.

Enable bus mastering only for Quark case.

Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
@@ -183,6 +183,8 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
 	if (ret)
 		return;
 
+	pci_set_master(pdev);
+
 	/* Special DMA address for UART */
 	dma->rx_dma_addr = 0xfffff000;
 	dma->tx_dma_addr = 0xfffff000;
@@ -280,8 +282,6 @@ static int lpss8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (ret)
 		return ret;
 
-	pci_set_master(pdev);
-
 	lpss = devm_kzalloc(&pdev->dev, sizeof(*lpss), GFP_KERNEL);
 	if (!lpss)
 		return -ENOMEM;
