From 8b9fce77737ae9983f61ec56cd53f52fb738b2c7 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 1 Apr 2010 11:24:23 -0700 Subject: [PATCH] iwlwifi: work around bogus active chains detection The current algorithm will sometimes "detect" that more chains are enabled than are really present in the device because, for unknown reasons, the ucode sends up all-zeroes signal values. The simplest way of solving this is to restrict the active chains mask to the chains we know are really present on the device. This fixes a bug with some devices where, since sometimes more chains are enabled than really present, the system would hang. Signed-off-by: Johannes Berg Signed-off-by: Reinette Chatre --- drivers/net/wireless/iwlwifi/iwl-calib.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/net/wireless/iwlwifi/iwl-calib.c b/drivers/net/wireless/iwlwifi/iwl-calib.c index 845831ac053e..64de42be7ea3 100644 --- a/drivers/net/wireless/iwlwifi/iwl-calib.c +++ b/drivers/net/wireless/iwlwifi/iwl-calib.c @@ -807,6 +807,18 @@ void iwl_chain_noise_calibration(struct iwl_priv *priv, } } + /* + * The above algorithm sometimes fails when the ucode + * reports 0 for all chains. It's not clear why that + * happens to start with, but it is then causing trouble + * because this can make us enable more chains than the + * hardware really has. + * + * To be safe, simply mask out any chains that we know + * are not on the device. + */ + active_chains &= priv->hw_params.valid_rx_ant; + num_tx_chains = 0; for (i = 0; i < NUM_RX_CHAINS; i++) { /* loops on all the bits of -- 2.20.1