From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BDFD5230BDF; Tue, 26 Aug 2025 13:10:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756213801; cv=none; b=nhLtgrLrMObSSM0VPb9ieyHuqOjnIOoKIZa+JJJKDb9zfsaxwy1BNDClKZ6X1JFO8L16Z8djSJXnJernlV5W4idxZ9/YsfWfqSygpCV3YMFp2XbMmdmIEV+hHyh5aLdFKdKco9ScJ8r0oT5om+3YLPzByoYraxi6COHi/7sxyYw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756213801; c=relaxed/simple; bh=xqcZswslpcV1SmLmHutzrJivp20MpaWfMouoqTTAg00=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XC+AxIpaNFyPZbxEtkcBb3+Vr29ogRCVbeyJkukhz9DUWz43Ati6XgvVOXTYEVyf4xlFRLBrolTxxPoyHRkZRdEMlR11uW8OfbO5TT/bUG+6H3yHBr2xvWrI/Ykj+7SYaI1QpbRkhzYnS5Bb4QArc1IoCgsFAif4WzF+Bmpz9uM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Q8PA/iqX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Q8PA/iqX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5066AC4CEF1; Tue, 26 Aug 2025 13:10:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756213801; bh=xqcZswslpcV1SmLmHutzrJivp20MpaWfMouoqTTAg00=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q8PA/iqXLTdkQG3hV4BXfj2nomw1U4nVK9Ec2M+MbK3fJw17uC9eWSQfx8/VBoIkA +a32X6CubOoyrxWgQ4fHSvHSJoKj81NH1ELGecbsJ3wYtS0mwJnVc+RMxVxi3xhLao HRZ5EVsiQ0JyvFYydyB6V9W77ir0rYYzVz9v4LcQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Sebastian Reichel , Heikki Krogerus , Sasha Levin Subject: [PATCH 6.6 443/587] usb: typec: fusb302: cache PD RX state Date: Tue, 26 Aug 2025 13:09:52 +0200 Message-ID: <20250826111004.226225859@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110952.942403671@linuxfoundation.org> References: <20250826110952.942403671@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Reichel [ Upstream commit 1e61f6ab08786d66a11cfc51e13d6f08a6b06c56 ] This patch fixes a race condition communication error, which ends up in PD hard resets when losing the race. Some systems, like the Radxa ROCK 5B are powered through USB-C without any backup power source and use a FUSB302 chip to do the PD negotiation. This means it is quite important to avoid hard resets, since that effectively kills the system's power-supply. I've found the following race condition while debugging unplanned power loss during booting the board every now and then: 1. lots of TCPM/FUSB302/PD initialization stuff 2. TCPM ends up in SNK_WAIT_CAPABILITIES (tcpm_set_pd_rx is enabled here) 3. the remote PD source does not send anything, so TCPM does a SOFT RESET 4. TCPM ends up in SNK_WAIT_CAPABILITIES for the second time (tcpm_set_pd_rx is enabled again, even though it is still on) At this point I've seen broken CRC good messages being send by the FUSB302 with a logic analyzer sniffing the CC lines. Also it looks like messages are being lost and things generally going haywire with one of the two sides doing a hard reset once a broken CRC good message was send to the bus. I think the system is running into a race condition, that the FIFOs are being cleared and/or the automatic good CRC message generation flag is being updated while a message is already arriving. Let's avoid this by caching the PD RX enabled state, as we have already processed anything in the FIFOs and are in a good state. As a side effect that this also optimizes I2C bus usage :) As far as I can tell the problem theoretically also exists when TCPM enters SNK_WAIT_CAPABILITIES the first time, but I believe this is less critical for the following reason: On devices like the ROCK 5B, which are powered through a TCPM backed USB-C port, the bootloader must have done some prior PD communication (initial communication must happen within 5 seconds after plugging the USB-C plug). This means the first time the kernel TCPM state machine reaches SNK_WAIT_CAPABILITIES, the remote side is not sending messages actively. On other devices a hard reset simply adds some extra delay and things should be good afterwards. Fixes: c034a43e72dda ("staging: typec: Fairchild FUSB302 Type-c chip driver") Cc: stable Signed-off-by: Sebastian Reichel Reviewed-by: Heikki Krogerus Link: https://lore.kernel.org/r/20250704-fusb302-race-condition-fix-v1-1-239012c0e27a@kernel.org Signed-off-by: Greg Kroah-Hartman [ Adjust context ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/usb/typec/tcpm/fusb302.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/usb/typec/tcpm/fusb302.c +++ b/drivers/usb/typec/tcpm/fusb302.c @@ -103,6 +103,7 @@ struct fusb302_chip { bool vconn_on; bool vbus_on; bool charge_on; + bool pd_rx_on; bool vbus_present; enum typec_cc_polarity cc_polarity; enum typec_cc_status cc1; @@ -841,6 +842,11 @@ static int tcpm_set_pd_rx(struct tcpc_de int ret = 0; mutex_lock(&chip->lock); + if (chip->pd_rx_on == on) { + fusb302_log(chip, "pd is already %s", str_on_off(on)); + goto done; + } + ret = fusb302_pd_rx_flush(chip); if (ret < 0) { fusb302_log(chip, "cannot flush pd rx buffer, ret=%d", ret); @@ -863,6 +869,8 @@ static int tcpm_set_pd_rx(struct tcpc_de on ? "on" : "off", ret); goto done; } + + chip->pd_rx_on = on; fusb302_log(chip, "pd := %s", on ? "on" : "off"); done: mutex_unlock(&chip->lock);