[media] soc-camera: Support user-configurable line stride

Add a capabilities field to the soc_camera_host structure to flag hosts
that support user-configurable line strides. soc_camera_try_fmt() then
passes the user-provided bytesperline and sizeimage format fields to
such hosts, and expects the host to check (and fix if needed) the
values.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[g.liakhovetski@gmx.de: fix a typo in mx2_camera.c]
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/mx2_camera.c

@@ -1787,6 +1787,8 @@ static int __devinit mx2_camera_probe(struct platform_device *pdev)
 	pcdev->soc_host.priv		= pcdev;
 	pcdev->soc_host.v4l2_dev.dev	= &pdev->dev;
 	pcdev->soc_host.nr		= pdev->id;
+	if (cpu_is_mx25())
+		pcdev->soc_host.capabilities = SOCAM_HOST_CAP_STRIDE;
 
 	pcdev->alloc_ctx = vb2_dma_contig_init_ctx(&pdev->dev);
 	if (IS_ERR(pcdev->alloc_ctx)) {

drivers/media/video/soc_camera.c

@@ -171,8 +171,10 @@ static int soc_camera_try_fmt(struct soc_camera_device *icd,
 	dev_dbg(icd->pdev, "TRY_FMT(%c%c%c%c, %ux%u)\n",
 		pixfmtstr(pix->pixelformat), pix->width, pix->height);
 
-	pix->bytesperline = 0;
-	pix->sizeimage = 0;
+	if (!(ici->capabilities & SOCAM_HOST_CAP_STRIDE)) {
+		pix->bytesperline = 0;
+		pix->sizeimage = 0;
+	}
 
 	ret = ici->ops->try_fmt(icd, f);
 	if (ret < 0)

include/media/soc_camera.h

@@ -56,11 +56,15 @@ struct soc_camera_device {
 	};
 };
 
+/* Host supports programmable stride */
+#define SOCAM_HOST_CAP_STRIDE		(1 << 0)
+
 struct soc_camera_host {
 	struct v4l2_device v4l2_dev;
 	struct list_head list;
 	struct mutex host_lock;		/* Protect during probing */
 	unsigned char nr;		/* Host number */
+	u32 capabilities;
 	void *priv;
 	const char *drv_name;
 	struct soc_camera_host_ops *ops;