media: adv748x-csi2: Validate the image format

The adv748x-csi2 driver configures the CSI-2 transmitter to
automatically infer the image stream format from the connected
frontend (HDMI or AFE).

Setting a new format on the subdevice hence does not actually control
the CSI-2 output format, but it's only there for the purpose of
pipeline validation.

However, there is currently no validation that the supplied media bus
code is valid and supported by the device.

With the introduction of enum_mbus_codes a list of supported format is
now available, use it to validate that the supplied format is correct
and use the default UYVY8 one if that's not the case.
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20240617161135.130719-8-jacopo.mondi@ideasonboard.comSigned-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

drivers/media/i2c/adv748x/adv748x-csi2.c

@@ -218,6 +218,22 @@ static int adv748x_csi2_get_format(struct v4l2_subdev *sd,
 	return 0;
 }
 
+static bool adv748x_csi2_is_fmt_supported(struct adv748x_csi2 *tx, u32 code)
+{
+	const unsigned int *codes = is_txa(tx) ?
+				    adv748x_csi2_txa_fmts :
+				    adv748x_csi2_txb_fmts;
+	size_t num_fmts = is_txa(tx) ? ARRAY_SIZE(adv748x_csi2_txa_fmts)
+				     : ARRAY_SIZE(adv748x_csi2_txb_fmts);
+
+	for (unsigned int i = 0; i < num_fmts; i++) {
+		if (codes[i] == code)
+			return true;
+	}
+
+	return false;
+}
+
 static int adv748x_csi2_set_format(struct v4l2_subdev *sd,
 				   struct v4l2_subdev_state *sd_state,
 				   struct v4l2_subdev_format *sdformat)
@@ -227,6 +243,13 @@ static int adv748x_csi2_set_format(struct v4l2_subdev *sd,
 	struct v4l2_mbus_framefmt *mbusformat;
 	int ret = 0;
 
+	/*
+	 * Make sure the format is supported, if not default it to
+	 * UYVY8 as it's supported by both TXes.
+	 */
+	if (!adv748x_csi2_is_fmt_supported(tx, sdformat->format.code))
+		sdformat->format.code = MEDIA_BUS_FMT_UYVY8_1X16;
+
 	mbusformat = adv748x_csi2_get_pad_format(sd, sd_state, sdformat->pad,
 						 sdformat->which);
 	if (!mbusformat)