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138 lines
4.3 KiB
Diff
138 lines
4.3 KiB
Diff
From: Sergey Ryazanov <ryazanov.s.a@gmail.com>
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Date: Wed, 4 Mar 2015 05:12:10 +0300
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Subject: [PATCH] ath5k: channel change fix
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ath5k updates the channel pointer and after that it stops the Rx logic
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and apply channel to HW. In case of channel switch, such sequence
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creates a small window when a frame, which is received on the old
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channel is considered as a frame received on the new one.
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The most notable consequence of this situation occurs during the switch
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from 2 GHz band (CCK+OFDM) to the 5GHz band (OFDM-only). Frame received
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with CCK rate, e.g. beacon received at the 1mbps, causes the following
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warning:
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WARNING: at ath5k/base.c:589 ath5k_tasklet_rx+0x318/0x6ec [ath5k]()
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invalid hw_rix: 1a
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[..]
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Call Trace:
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[<802656a8>] show_stack+0x48/0x70
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[<802dd92c>] warn_slowpath_common+0x88/0xbc
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[<802dd98c>] warn_slowpath_fmt+0x2c/0x38
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[<81b51be8>] ath5k_tasklet_rx+0x318/0x6ec [ath5k]
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[<8028ac64>] tasklet_action+0x8c/0xf0
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[<80075804>] __do_softirq+0x180/0x32c
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[<80196ce8>] irq_exit+0x54/0x70
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[<80041848>] ret_from_irq+0x0/0x4
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[<80182fdc>] ioread32+0x4/0xc
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[<81b4c42c>] ath5k_hw_set_sleep_clock+0x2ec/0x474 [ath5k]
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[<81b4cf28>] ath5k_hw_reset+0x50/0xeb8 [ath5k]
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[<81b50900>] ath5k_reset+0xd4/0x310 [ath5k]
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[<81b557e8>] ath5k_config+0x4c/0x104 [ath5k]
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[<80d01770>] ieee80211_hw_config+0x2f4/0x35c [mac80211]
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[<80d09aa8>] ieee80211_scan_work+0x2e4/0x414 [mac80211]
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[<8022c3f4>] process_one_work+0x28c/0x400
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[<802df8f8>] worker_thread+0x258/0x3c0
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[<801b5710>] kthread+0xe0/0xec
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[<800418a8>] ret_from_kernel_thread+0x14/0x1c
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The easiest way to reproduce this warning is to run scan with dualband
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NIC in noisy environments, when the channel 11 runs multiple APs. In my
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tests if the APs num >= 12, the warning appears in the first few
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seconds of scanning.
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In order to fix this, the Rx disable code moved to a higher level and
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placed before the channel pointer update. This is also makes the code a
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bit more symmetrical, since we disable and enable the Rx in the same
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function.
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In fact, at the pointer update time new frames should not appear,
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because interrupt generation at this point should already be disabled.
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The next patch should address this issue.
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CC: Jiri Slaby <jirislaby@gmail.com>
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CC: Nick Kossifidis <mickflemm@gmail.com>
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CC: Luis R. Rodriguez <mcgrof@do-not-panic.com>
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Reported-by: Christophe Prevotaux <cprevotaux@nltinc.com>
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Tested-by: Christophe Prevotaux <cprevotaux@nltinc.com>
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Tested-by: Eric Bree <ebree@nltinc.com>
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Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
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---
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--- a/drivers/net/wireless/ath/ath5k/base.c
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+++ b/drivers/net/wireless/ath/ath5k/base.c
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@@ -2858,7 +2858,7 @@ ath5k_reset(struct ath5k_hw *ah, struct
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{
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struct ath_common *common = ath5k_hw_common(ah);
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int ret, ani_mode;
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- bool fast;
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+ bool fast = chan && modparam_fastchanswitch ? 1 : 0;
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ATH5K_DBG(ah, ATH5K_DEBUG_RESET, "resetting\n");
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@@ -2876,11 +2876,29 @@ ath5k_reset(struct ath5k_hw *ah, struct
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* so we should also free any remaining
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* tx buffers */
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ath5k_drain_tx_buffs(ah);
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+
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+ /* Stop PCU */
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+ ath5k_hw_stop_rx_pcu(ah);
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+
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+ /* Stop DMA
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+ *
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+ * Note: If DMA didn't stop continue
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+ * since only a reset will fix it.
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+ */
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+ ret = ath5k_hw_dma_stop(ah);
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+
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+ /* RF Bus grant won't work if we have pending
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+ * frames
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+ */
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+ if (ret && fast) {
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+ ATH5K_DBG(ah, ATH5K_DEBUG_RESET,
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+ "DMA didn't stop, falling back to normal reset\n");
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+ fast = false;
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+ }
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+
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if (chan)
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ah->curchan = chan;
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- fast = ((chan != NULL) && modparam_fastchanswitch) ? 1 : 0;
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-
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ret = ath5k_hw_reset(ah, ah->opmode, ah->curchan, fast, skip_pcu);
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if (ret) {
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ATH5K_ERR(ah, "can't reset hardware (%d)\n", ret);
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--- a/drivers/net/wireless/ath/ath5k/reset.c
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+++ b/drivers/net/wireless/ath/ath5k/reset.c
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@@ -1169,30 +1169,6 @@ ath5k_hw_reset(struct ath5k_hw *ah, enum
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if (ah->ah_version == AR5K_AR5212)
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ath5k_hw_set_sleep_clock(ah, false);
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- /*
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- * Stop PCU
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- */
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- ath5k_hw_stop_rx_pcu(ah);
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-
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- /*
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- * Stop DMA
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- *
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- * Note: If DMA didn't stop continue
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- * since only a reset will fix it.
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- */
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- ret = ath5k_hw_dma_stop(ah);
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-
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- /* RF Bus grant won't work if we have pending
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- * frames */
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- if (ret && fast) {
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- ATH5K_DBG(ah, ATH5K_DEBUG_RESET,
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- "DMA didn't stop, falling back to normal reset\n");
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- fast = false;
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- /* Non fatal, just continue with
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- * normal reset */
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- ret = 0;
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- }
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-
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mode = channel->hw_value;
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switch (mode) {
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case AR5K_MODE_11A:
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