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authorEmmanuel Grumbach <emmanuel.grumbach@intel.com>2013-12-24 14:15:41 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-06 11:08:17 -0800
commit50920a1dd85602169df04e38248fa582d523c039 (patch)
tree6269e8ddd2fbee4a9eb845fb3a46fdfcaf980f3d /drivers/net
parent38c963f2676af60291566a1ae470b09d293adccd (diff)
downloadlinaro-lsk-50920a1dd85602169df04e38248fa582d523c039.tar.gz
iwlwifi: pcie: enable oscillator for L1 exit
commit 2d93aee152b1758a94a18fe15d72153ba73b5679 upstream. Enabling the oscillator consumes slightly more power (100uA) but allows to make sure that we exit from L1 on time. Not doing so might lead to a PCIe specification violation since we might wake up from L1 at the wrong time. This issue has been identified on 3160 and 7260 only. On older NICs L1 off is not enabled, on newer NICs (7265), the issue is fixed. When the bug occurs the user sees that the NIC has disappeared from the PCI bridge, any access to the device returns 0xff. This fixes: https://bugzilla.kernel.org/show_bug.cgi?id=64541 and has been extensively discussed here: http://markmail.org/thread/mfmpzqt3r333n4bo Fixes: 99cd47142399 ("iwlwifi: add 7000 series device configuration") Reported-and-tested-by: wzyboy <wzyboy@wzyboy.org> Reviewed-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/wireless/iwlwifi/iwl-prph.h4
-rw-r--r--drivers/net/wireless/iwlwifi/pcie/trans.c16
2 files changed, 20 insertions, 0 deletions
diff --git a/drivers/net/wireless/iwlwifi/iwl-prph.h b/drivers/net/wireless/iwlwifi/iwl-prph.h
index 386f2a7c87c..c26a6dc21ee 100644
--- a/drivers/net/wireless/iwlwifi/iwl-prph.h
+++ b/drivers/net/wireless/iwlwifi/iwl-prph.h
@@ -260,4 +260,8 @@ static inline unsigned int SCD_QUEUE_STATUS_BITS(unsigned int chnl)
/*********************** END TX SCHEDULER *************************************/
+/* Oscillator clock */
+#define OSC_CLK (0xa04068)
+#define OSC_CLK_FORCE_CONTROL (0x8)
+
#endif /* __iwl_prph_h__ */
diff --git a/drivers/net/wireless/iwlwifi/pcie/trans.c b/drivers/net/wireless/iwlwifi/pcie/trans.c
index aeb70e13137..95ed2a676d7 100644
--- a/drivers/net/wireless/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/iwlwifi/pcie/trans.c
@@ -207,6 +207,22 @@ static int iwl_pcie_apm_init(struct iwl_trans *trans)
}
/*
+ * Enable the oscillator to count wake up time for L1 exit. This
+ * consumes slightly more power (100uA) - but allows to be sure
+ * that we wake up from L1 on time.
+ *
+ * This looks weird: read twice the same register, discard the
+ * value, set a bit, and yet again, read that same register
+ * just to discard the value. But that's the way the hardware
+ * seems to like it.
+ */
+ iwl_read_prph(trans, OSC_CLK);
+ iwl_read_prph(trans, OSC_CLK);
+ iwl_set_bits_prph(trans, OSC_CLK, OSC_CLK_FORCE_CONTROL);
+ iwl_read_prph(trans, OSC_CLK);
+ iwl_read_prph(trans, OSC_CLK);
+
+ /*
* Enable DMA clock and wait for it to stabilize.
*
* Write to "CLK_EN_REG"; "1" bits enable clocks, while "0" bits