This is a note to let you know that I've just added the patch titled
iwlwifi: pcie: enable oscillator for L1 exit
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iwlwifi-pcie-enable-oscillator-for-l1-exit.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2d93aee152b1758a94a18fe15d72153ba73b5679 Mon Sep 17 00:00:00 2001
From: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
Date: Tue, 24 Dec 2013 14:15:41 +0200
Subject: iwlwifi: pcie: enable oscillator for L1 exit
From: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
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@xxxxxxxxxx>
Reviewed-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/wireless/iwlwifi/iwl-prph.h | 4 ++++
drivers/net/wireless/iwlwifi/pcie/trans.c | 16 ++++++++++++++++
2 files changed, 20 insertions(+)
--- 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_STA
/*********************** END TX SCHEDULER *************************************/
+/* Oscillator clock */
+#define OSC_CLK (0xa04068)
+#define OSC_CLK_FORCE_CONTROL (0x8)
+
#endif /* __iwl_prph_h__ */
--- 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_
}
/*
+ * 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
Patches currently in stable-queue which might be from emmanuel.grumbach@xxxxxxxxx are
queue-3.10/iwlwifi-mvm-fix-missing-cleanup-in-.start-error-path.patch
queue-3.10/iwlwifi-pcie-enable-oscillator-for-l1-exit.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html