This is a note to let you know that I've just added the patch titled
rtlwifi: rtl8821ae: Fix connection lost problem correctly
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: rtlwifi-rtl8821ae-fix-connection-lost-problem-correctly.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From c713fb071edc0efc01a955f65a006b0e1795d2eb Mon Sep 17 00:00:00 2001
From: Larry Finger Larry.Finger@lwfinger.net Date: Mon, 5 Feb 2018 12:38:11 -0600 Subject: rtlwifi: rtl8821ae: Fix connection lost problem correctly
From: Larry Finger Larry.Finger@lwfinger.net
commit c713fb071edc0efc01a955f65a006b0e1795d2eb upstream.
There has been a coding error in rtl8821ae since it was first introduced, namely that an 8-bit register was read using a 16-bit read in _rtl8821ae_dbi_read(). This error was fixed with commit 40b368af4b75 ("rtlwifi: Fix alignment issues"); however, this change led to instability in the connection. To restore stability, this change was reverted in commit b8b8b16352cd ("rtlwifi: rtl8821ae: Fix connection lost problem").
Unfortunately, the unaligned access causes machine checks in ARM architecture, and we were finally forced to find the actual cause of the problem on x86 platforms. Following a suggestion from Pkshih pkshih@realtek.com, it was found that increasing the ASPM L1 latency from 0 to 7 fixed the instability. This parameter was varied to see if a smaller value would work; however, it appears that 7 is the safest value. A new symbol is defined for this quantity, thus it can be easily changed if necessary.
Fixes: b8b8b16352cd ("rtlwifi: rtl8821ae: Fix connection lost problem") Cc: Stable stable@vger.kernel.org # 4.14+ Fix-suggested-by: Pkshih pkshih@realtek.com Signed-off-by: Larry Finger Larry.Finger@lwfinger.net Tested-by: James Cameron quozl@laptop.org # x86_64 OLPC NL3 Signed-off-by: Kalle Valo kvalo@codeaurora.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/wireless/realtek/rtlwifi/rtl8821ae/hw.c | 5 +++-- drivers/net/wireless/realtek/rtlwifi/wifi.h | 1 + 2 files changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/hw.c +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8821ae/hw.c @@ -1128,7 +1128,7 @@ static u8 _rtl8821ae_dbi_read(struct rtl } if (0 == tmp) { read_addr = REG_DBI_RDATA + addr % 4; - ret = rtl_read_word(rtlpriv, read_addr); + ret = rtl_read_byte(rtlpriv, read_addr); } return ret; } @@ -1170,7 +1170,8 @@ static void _rtl8821ae_enable_aspm_back_ }
tmp = _rtl8821ae_dbi_read(rtlpriv, 0x70f); - _rtl8821ae_dbi_write(rtlpriv, 0x70f, tmp | BIT(7)); + _rtl8821ae_dbi_write(rtlpriv, 0x70f, tmp | BIT(7) | + ASPM_L1_LATENCY << 3);
tmp = _rtl8821ae_dbi_read(rtlpriv, 0x719); _rtl8821ae_dbi_write(rtlpriv, 0x719, tmp | BIT(3) | BIT(4)); --- a/drivers/net/wireless/realtek/rtlwifi/wifi.h +++ b/drivers/net/wireless/realtek/rtlwifi/wifi.h @@ -99,6 +99,7 @@ #define RTL_USB_MAX_RX_COUNT 100 #define QBSS_LOAD_SIZE 5 #define MAX_WMMELE_LENGTH 64 +#define ASPM_L1_LATENCY 7
#define TOTAL_CAM_ENTRY 32
Patches currently in stable-queue which might be from Larry.Finger@lwfinger.net are
queue-4.9/rtlwifi-rtl8821ae-fix-connection-lost-problem-correctly.patch