[media] marvell-cam: implement contiguous DMA operation

The core driver can now operate in either vmalloc or dma-contig modes;
obviously the latter is preferable when it is supported.  Default is
currently vmalloc on all platforms; load the module with buffer_mode=1 for
contiguous DMA mode.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/marvell-ccic/Kconfig

@@ -14,6 +14,7 @@ config VIDEO_MMP_CAMERA
 	select VIDEO_OV7670
 	select I2C_GPIO
 	select VIDEOBUF2_VMALLOC
+	select VIDEOBUF2_DMA_CONTIG
 	---help---
 	  This is a Video4Linux2 driver for the integrated camera
 	  controller found on Marvell Armada 610 application

drivers/media/video/marvell-ccic/cafe-driver.c

@@ -481,6 +481,12 @@ static int cafe_pci_probe(struct pci_dev *pdev,
 	 */
 	mcam->clock_speed = 45;
 	mcam->use_smbus = 1;
+	/*
+	 * Vmalloc mode for buffers is traditional with this driver.
+	 * We *might* be able to run DMA_contig, especially on a system
+	 * with CMA in it.
+	 */
+	mcam->buffer_mode = B_vmalloc;
 	/*
 	 * Get set up on the PCI bus.
 	 */