From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x225fN9/CslvqeWrZYZ8f1fZDcydTgbBM8EY2gIcH0EFQeo+hhMt7sEHRoWQAAUrCletI5GQx ARC-Seal: i=1; a=rsa-sha256; t=1519218688; cv=none; d=google.com; s=arc-20160816; b=Ttw6cE1mbjvQnQ42D63/Zr5yGGOGgSnA0rJAyzf/6FzZyhAWEoX+8M4i0+X7Kqh2I5 3L5yqXFhZYXmUAmZ/U0KGpiVvfGTVo3cDhQyw4Vqt1CVYOY5I7548qm74zYlUD7M3Ero wNzkl5WZBrvsuvyeAN9RN0Xp1jFVj/EMT3RH4hh83gfj8q9HHrky5U7Ffsmlj+WjgEu9 yqswoxHzf+MSEjadwuVcMeXhh6k9Mv5X2wgsZALI4nszHhwK652L2jtlzFufD+xleqPJ 7XH0P4AolsgowlJwVNdo5ILMUglWSXgJvgdpb0NJR2DhPTJBldeEU6FhY6w01jiXQKER wzig== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=NdzJwEZq5tbb2GGhsLJLdk7tBNMa8z0lmtzIKTUeE6Y=; b=A5TrYcx8w0Iiawf7XCfKKS+BTp+dlAwjHIZ2zqOITbvStAefT4M7wyMoSLu61hRRaA Ml0x38ZniJxVAx2Q0Vbj/3hQkEjAlvWUkXNPEBTaHqWClovvhrQ9KWoq7uYISQJI7IOy f2qKBgJeH1M2YbRz6H04y4q8YIAR7mXjnllhr8fDG55SF27tH5/9BCLv04ZLJ6+PB4ph HpbWP3I/mBBLIdswj/6Kx2yqzD2ou6+V5ilRIN2JwYFfDZSNCOOIiJn/ehRQWwtALMef DVpb3VOCZpiyDDCV8Ae0/+d7EepXIdvdHuH4cVQzemDeoOi7+/fNAowFJHWVrMZkMt/k 0hgA== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Larry Finger , Kalle Valo Subject: [PATCH 4.15 127/163] rtlwifi: rtl8821ae: Fix connection lost problem correctly Date: Wed, 21 Feb 2018 13:49:16 +0100 Message-Id: <20180221124537.155053230@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180221124529.931834518@linuxfoundation.org> References: <20180221124529.931834518@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1593014634978594268?= X-GMAIL-MSGID: =?utf-8?q?1593016255206586890?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Larry Finger 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 , 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 # 4.14+ Fix-suggested-by: Pkshih Signed-off-by: Larry Finger Tested-by: James Cameron # x86_64 OLPC NL3 Signed-off-by: Kalle Valo Signed-off-by: Greg Kroah-Hartman --- 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 @@ -1123,7 +1123,7 @@ 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; } @@ -1165,7 +1165,8 @@ 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