2014-11-20 20:10:57

by Catalin Iacob

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Subject: rtl8192ce 3.18 regression scan doesn't find any APs

Since the 3.18 merge window my wireless card cannot find any access
point (tested with both NetworkManager and sudo /usr/sbin/iw dev
wlp2s0 scan). More precisely, in 3.18-rc1 I got the oops described at
http://marc.info/?l=linux-wireless&m=141324391807122&w=2. Sometime
after rc1 Larry fixed this but when I tested again I found that scan
doesn't work (tested 3.18-rc3 and just now 3.18-rc5).

According to lspci -nn my hardware is:
02:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd.
RTL8188CE 802.11b/g/n WiFi Adapter [10ec:8176] (rev 01)

If I grep dmesg for rtl, for 3.17 which works I get:
[ 31.208206] rtl8192ce:_rtl92ce_read_chip_version():<0-0> Chip
Version ID: B_CHIP_88C
[ 31.219973] rtl8192ce: Using firmware rtlwifi/rtl8192cfw.bin
[ 31.861478] ieee80211 phy0: Selected rate control algorithm 'rtl_rc'
[ 31.865655] rtlwifi: wireless switch is on
[ 31.872019] rtl8192ce 0000:02:00.0 wlp2s0: renamed from wlan0
[ 41.428487] rtl8192ce 0000:02:00.0 wlp2s0: disabling HT as WMM/QoS
is not supported by the AP
[ 41.428499] rtl8192ce 0000:02:00.0 wlp2s0: disabling VHT as WMM/QoS
is not supported by the AP

3.18 says:
[ 29.213829] rtl8192ce:_rtl92ce_read_chip_version():<0-0> Chip
Version ID: B_CHIP_88C
[ 29.230599] rtl8192ce: Using firmware rtlwifi/rtl8192cfw.bin
[ 29.330232] ieee80211 phy0: Selected rate control algorithm 'rtl_rc'
[ 29.332250] rtlwifi: rtlwifi: wireless switch is on
[ 29.339416] rtl8192ce 0000:02:00.0 wlp2s0: renamed from wlan0
[ 344.942070] rtl8192ce:rtl92ce_get_hw_reg():<0-0> switch case not processed

I added some debug prints and the last line comes from core.c,
rtl_op_stop which calls get_hw_reg with HAL_DEF_WOWLAN. This happens
indeed when I untick Enable wireless in NetworkManager. I assume it's
not related to the more serious scan issue.

How can I help with debugging this?


2014-11-20 22:34:12

by Larry Finger

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Subject: Re: rtl8192ce 3.18 regression scan doesn't find any APs

On 11/20/2014 02:10 PM, Catalin Iacob wrote:
> Since the 3.18 merge window my wireless card cannot find any access
> point (tested with both NetworkManager and sudo /usr/sbin/iw dev
> wlp2s0 scan). More precisely, in 3.18-rc1 I got the oops described at
> http://marc.info/?l=linux-wireless&m=141324391807122&w=2. Sometime
> after rc1 Larry fixed this but when I tested again I found that scan
> doesn't work (tested 3.18-rc3 and just now 3.18-rc5).
>
> According to lspci -nn my hardware is:
> 02:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd.
> RTL8188CE 802.11b/g/n WiFi Adapter [10ec:8176] (rev 01)
>
> If I grep dmesg for rtl, for 3.17 which works I get:
> [ 31.208206] rtl8192ce:_rtl92ce_read_chip_version():<0-0> Chip
> Version ID: B_CHIP_88C
> [ 31.219973] rtl8192ce: Using firmware rtlwifi/rtl8192cfw.bin
> [ 31.861478] ieee80211 phy0: Selected rate control algorithm 'rtl_rc'
> [ 31.865655] rtlwifi: wireless switch is on
> [ 31.872019] rtl8192ce 0000:02:00.0 wlp2s0: renamed from wlan0
> [ 41.428487] rtl8192ce 0000:02:00.0 wlp2s0: disabling HT as WMM/QoS
> is not supported by the AP
> [ 41.428499] rtl8192ce 0000:02:00.0 wlp2s0: disabling VHT as WMM/QoS
> is not supported by the AP
>
> 3.18 says:
> [ 29.213829] rtl8192ce:_rtl92ce_read_chip_version():<0-0> Chip
> Version ID: B_CHIP_88C
> [ 29.230599] rtl8192ce: Using firmware rtlwifi/rtl8192cfw.bin
> [ 29.330232] ieee80211 phy0: Selected rate control algorithm 'rtl_rc'
> [ 29.332250] rtlwifi: rtlwifi: wireless switch is on
> [ 29.339416] rtl8192ce 0000:02:00.0 wlp2s0: renamed from wlan0
> [ 344.942070] rtl8192ce:rtl92ce_get_hw_reg():<0-0> switch case not processed
>
> I added some debug prints and the last line comes from core.c,
> rtl_op_stop which calls get_hw_reg with HAL_DEF_WOWLAN. This happens
> indeed when I untick Enable wireless in NetworkManager. I assume it's
> not related to the more serious scan issue.
>
> How can I help with debugging this?

I do not believe that "switch case not processed" is serious, but I will check it.

I have reproduced the problem, but I do not yet know the fix. Please file a bug
report at bugzilla.kernel.org on this problem. Be sure to mark it as a
regression, and assign it to me. When I find the fix, being able to cite the bug
report will help get a last-minute patch into 3.18.

Larry



2014-11-26 19:58:32

by Catalin Iacob

[permalink] [raw]
Subject: Re: rtl8192ce 3.18 regression scan doesn't find any APs

On Thu, Nov 20, 2014 at 11:34 PM, Larry Finger
<[email protected]> wrote:
> I have reproduced the problem, but I do not yet know the fix. Please file a
> bug report at bugzilla.kernel.org on this problem. Be sure to mark it as a
> regression, and assign it to me. When I find the fix, being able to cite the
> bug report will help get a last-minute patch into 3.18.

Thanks for looking at this. Great that you could reproduce it.

I've filed https://bugzilla.kernel.org/show_bug.cgi?id=88951 and added
you to CC since I don't have permissions to change the Assigned to
field.