On Tue, Oct 22, 2013 at 08:08:12AM +0200, Florian Echtler wrote:

Hello Dmitry,

thanks for your quick feedback, a few questions below:

On 21.10.2013 18:20, Dmitry Torokhov wrote:

quoted

On Sun, Oct 20, 2013 at 06:49:11PM +0200, Florian Echtler wrote:

quoted

+/* read 512 bytes from endpoint 0x86 -> get header + blobs */
+struct sur40_header {
+
+	uint16_t type;       /* always 0x0001 */
+	uint16_t count;      /* count of blobs (if 0: continue prev. packet) */
+
+	uint32_t packet_id;
+
+	uint32_t timestamp;  /* milliseconds (inc. by 16 or 17 each frame) */
+	uint32_t unknown;    /* "epoch?" always 02/03 00 00 00 */

Proper internal kernel types are u8, u16, u32. For user-facing APIs
__u8, __u16, and __u32 should be used. Also, since this is data coming
directly off the wire, you should be using __le16, __le32, etc, and then
do __leXX_to_cpu() conversion before using it in calculations.

OK, I'll switch to u32 throughout (also for the float, I'll explain in a
commment). However, I haven't found a single other touchscreen driver
which uses __le32, even though they all probably process raw wire data -
can you suggest an example?

Not necessarily le32, but:

[dtor@dtor-d630 work]$ grep -ri to_cpu drivers/input/touchscreen/
drivers/input/touchscreen/atmel_mxt_ts.c:
le16_to_cpus(&object->start_address);
drivers/input/touchscreen/atmel_mxt_ts.c:       le16_to_cpus(range.x);
drivers/input/touchscreen/atmel_mxt_ts.c:       le16_to_cpus(range.y);
drivers/input/touchscreen/cyttsp_core.c: input_report_abs(input, ABS_MT_POSITION_X, be16_to_cpu(tch->x));
drivers/input/touchscreen/cyttsp_core.c: input_report_abs(input, ABS_MT_POSITION_Y, be16_to_cpu(tch->y));
drivers/input/touchscreen/ads7846.c:            status = be16_to_cpu(req->sample);
drivers/input/touchscreen/ads7846.c:            status = be16_to_cpu(*((u16 *)&req->sample[1]));
drivers/input/touchscreen/ads7846.c:            return be16_to_cpup((__be16 *)&(((char*)t->rx_buf)[1])) >> 3;
drivers/input/touchscreen/ads7846.c:            return be16_to_cpup((__be16 *)t->rx_buf) >> 3;
drivers/input/touchscreen/usbtouchscreen.c:     unsigned int data_len = be16_to_cpu(packet->data_len);
drivers/input/touchscreen/usbtouchscreen.c:     unsigned int x_len = be16_to_cpu(packet->x_len);
drivers/input/touchscreen/usbtouchscreen.c:     unsigned int y_len = be16_to_cpu(packet->y_len);
drivers/input/touchscreen/usbtouchscreen.c: le16_to_cpu(udev->descriptor.idVendor),
drivers/input/touchscreen/usbtouchscreen.c: le16_to_cpu(udev->descriptor.idProduct));
drivers/input/touchscreen/wacom_i2c.c:  x = le16_to_cpup((__le16 *)&data[4]);
drivers/input/touchscreen/wacom_i2c.c:  y = le16_to_cpup((__le16 *)&data[6]);
drivers/input/touchscreen/wacom_i2c.c:  pressure = le16_to_cpup((__le16 *)&data[8]);

quoted

quoted

+/* debug helper macro */
+#define get_dev(x) (&(x->usbdev->dev))

Just stick that dev in sur40_state and then use sur40->dev throughout.

OK.

quoted

quoted

+	struct sur40_header *header = &(sur40->bulk_in_buffer->header);

No need to have parenthesis around & operator.

quoted

+	struct sur40_blob *inblob = &(sur40->bulk_in_buffer->blobs[0]);

Same here.

Intention seems clearer to me with parentheses, but if this doesn't
conform to coding style, I'll fix it.

quoted

quoted

+	if (!sur40->bulk_in_buffer) {
+		dev_err(&interface->dev, "Unable to allocate input buffer.");
+		sur40_delete(sur40);

Would prefer standard kernel error unwinding style (gotos to proper
unwinding point).

Something like this example from ucb1400_ts?

	error = input_register_device(ucb->ts_idev);
	if (error)
		goto err_free_irq;

	return 0;

err_free_irq:
	free_irq(ucb->irq, ucb);
err_free_devs:
	input_free_device(ucb->ts_idev);
err:
	return error;

Yes, please.

-- 
Dmitry