Re: [RFC PATCH 2/3] radio-keene: add a driver for the Keene FM Transmitter.

Am Montag, 16. Januar 2012, 13:29:19 schrieb Hans Verkuil:

From: Hans Verkuil <redacted>

+MODULE_DEVICE_TABLE(usb, usb_keene_device_table);
+
+struct keene_device {
+	struct usb_device *usbdev;
+	struct usb_interface *intf;
+	struct video_device vdev;
+	struct v4l2_device v4l2_dev;
+	struct v4l2_ctrl_handler hdl;
+	struct mutex lock;
+
+	u8 buffer[BUFFER_LENGTH];

This is a violation of the DMA  API. You need to alocate the buffer with
a separate kmalloc.

+	unsigned curfreq;
+	u8 tx;
+	u8 pa;
+	bool stereo;
+	bool muted;
+	bool preemph_75_us;
+};
+
+static inline struct keene_device *to_keene_dev(struct v4l2_device *v4l2_dev)
+{
+	return container_of(v4l2_dev, struct keene_device, v4l2_dev);
+}
+
+/* Set frequency (if non-0), PA, mute and turn on/off the FM transmitter. */
+static int keene_cmd_main(struct keene_device *radio, unsigned freq, bool play)
+{
+	unsigned short freq_send = freq ? (freq - 76 * 16000) / 800 : 0;
+	int ret;
+
+	radio->buffer[0] = 0x00;
+	radio->buffer[1] = 0x50;
+	radio->buffer[2] = (freq_send >> 8) & 0xff;
+	radio->buffer[3] = freq_send & 0xff;

Please use the endianness macro appropriate here

	Regards
		Oliver