From 444fb98eed98f7292a83f9bf123d1c78f171327e Mon Sep 17 00:00:00 2001 From: Thierry Escande Date: Thu, 2 Jan 2014 11:58:12 +0100 Subject: [PATCH] NFC: digital: Add a note about asynchronous functions This explains how and why the timeout parameter must be handled by the driver implementation. Signed-off-by: Samuel Ortiz --- include/net/nfc/digital.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/net/nfc/digital.h b/include/net/nfc/digital.h index 36acecd..81af21e 100644 --- a/include/net/nfc/digital.h +++ b/include/net/nfc/digital.h @@ -122,6 +122,16 @@ typedef void (*nfc_digital_cmd_complete_t)(struct nfc_digital_dev *ddev, * switch_rf to turn the radio on. A call to in|tg_configure_hw must turn * the device radio on. * @abort_cmd: Discard the last sent command. + * + * Notes: Asynchronous functions have a timeout parameter. It is the driver + * responsibility to call the digital stack back through the + * nfc_digital_cmd_complete_t callback when no RF respsonse has been + * received within the specified time (in milliseconds). In that case the + * driver must set the resp sk_buff to ERR_PTR(-ETIMEDOUT). + * Since the digital stack serializes commands to be sent, it's mandatory + * for the driver to handle the timeout correctly. Otherwise the stack + * would not be able to send new commands, waiting for the reply of the + * current one. */ struct nfc_digital_ops { int (*in_configure_hw)(struct nfc_digital_dev *ddev, int type, -- 2.7.4