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NFC: digital: Randomize poll cycles 

This change adds some entropy to polling cycles, choosing the next
polling rf technology randomly. This reflects the change done in the
pn533 driver, avoiding possible infinite loop for devices that export 2
targets on 2 different modulations. If the first target is not
readable, we will stay in an error loop for ever.

Signed-off-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Thierry Escande 2014-05-10 13:06:02 +02:00 committed by Samuel Ortiz
parent 00e625df3e
commit 9dc33705b2
1 changed files with 4 additions and 2 deletions
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6
net/nfc/digital_core.c
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@ -386,6 +386,8 @@ int digital_target_found(struct nfc_digital_dev *ddev,
void digital_poll_next_tech(struct nfc_digital_dev *ddev)
{
u8 rand_mod;
digital_switch_rf(ddev, 0);
mutex_lock(&ddev->poll_lock);
@ -395,8 +397,8 @@ void digital_poll_next_tech(struct nfc_digital_dev *ddev)
return;
}
ddev->poll_tech_index = (ddev->poll_tech_index + 1) %
ddev->poll_tech_count;
get_random_bytes(&rand_mod, sizeof(rand_mod));
ddev->poll_tech_index = rand_mod % ddev->poll_tech_count;
mutex_unlock(&ddev->poll_lock);