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[media] ati_remote: Check the checksum

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An input report is 4 bytes long, but there are only 12 bits
of actual payload.  The 4 bytes are:
data[0] = 0x14
data[1] = data[2] + data[3] + 0xd5 (a checksum byte)
data[2] = the raw scancode (plus toggle bit in msbit)
data[3] = channel << 4 (the low 4 bits must be zero)

Ignore reports with a bad checksum.

Signed-off-by: George Spelvin <linux@horizon.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
George Spelvin 2014-05-11 08:12:09 -03:00 committed by Mauro Carvalho Chehab
parent 7cec72ce00
commit 20d7e3ca1b
1 changed files with 5 additions and 4 deletions
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9
drivers/media/rc/ati_remote.c
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@ -507,8 +507,9 @@ static void ati_remote_input_report(struct urb *urb)
*/
/* Deal with strange looking inputs */
if ( (urb->actual_length != 4) || (data[0] != 0x14) ||
((data[3] & 0x0f) != 0x00) ) {
if ( urb->actual_length != 4 || data[0] != 0x14 ||
data[1] != (unsigned char)(data[2] + data[3] + 0xD5) ||
(data[3] & 0x0f) != 0x00) {
ati_remote_dump(&urb->dev->dev, data, urb->actual_length);
return;
}
@ -524,9 +525,9 @@ static void ati_remote_input_report(struct urb *urb)
remote_num = (data[3] >> 4) & 0x0f;
if (channel_mask & (1 << (remote_num + 1))) {
dbginfo(&ati_remote->interface->dev,
"Masked input from channel 0x%02x: data %02x,%02x, "
"Masked input from channel 0x%02x: data %02x, "
"mask= 0x%02lx\n",
remote_num, data[1], data[2], channel_mask);
remote_num, data[2], channel_mask);
return;
}