Re: [PATCH v2] add sur40 driver for Samsung SUR40 (aka MS Surface 2.0/Pixelsense)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hello Dmitry,

thanks for your quick feedback, a few questions below:

On 21.10.2013 18:20, Dmitry Torokhov wrote:
> On Sun, Oct 20, 2013 at 06:49:11PM +0200, Florian Echtler wrote:
>> +/* 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?

>> +/* debug helper macro */
>> +#define get_dev(x) (&(x->usbdev->dev))
> Just stick that dev in sur40_state and then use sur40->dev throughout.
OK.

>> +	struct sur40_header *header = &(sur40->bulk_in_buffer->header);
> No need to have parenthesis around & operator.
>> +	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.

>> +	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;


Best regards, Florian
-- 
SENT FROM MY DEC VT50 TERMINAL

Attachment: signature.asc
Description: OpenPGP digital signature


[Index of Archives]     [Linux Media Devel]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Linux Wireless Networking]     [Linux Omap]

  Powered by Linux