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[34.141.175.244]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-608b4a94ce7sm6036664a12.58.2025.06.16.06.33.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Jun 2025 06:33:18 -0700 (PDT) From: Andrei Kuchynski To: Heikki Krogerus , Dmitry Baryshkov , Abhishek Pandit-Subedi , Jameson Thies , Benson Leung , Tzung-Bi Shih Cc: Greg Kroah-Hartman , Guenter Roeck , Pooja Katiyar , Badhri Jagan Sridharan , RD Babiera , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, chrome-platform@lists.linux.dev, Andrei Kuchynski Subject: [PATCH 06/10] Revert "usb: typec: displayport: Receive DP Status Update NAK request exit dp altmode" Date: Mon, 16 Jun 2025 13:31:43 +0000 Message-ID: <20250616133147.1835939-7-akuchynski@chromium.org> X-Mailer: git-send-email 2.50.0.rc1.591.g9c95f17f64-goog In-Reply-To: <20250616133147.1835939-1-akuchynski@chromium.org> References: <20250616133147.1835939-1-akuchynski@chromium.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This reverts commit b4b38ffb38c91afd4dc387608db26f6fc34ed40b. The commit introduced a deadlock with the cros_ec_typec driver. The deadlock occurs due to a recursive lock acquisition of `cros_typec_altmode_work::mutex`. The call chain is as follows:=20 1. cros_typec_altmode_work() acquires the mutex 2. typec_altmode_vdm() -> dp_altmode_vdm() -> 3. typec_altmode_exit() -> cros_typec_altmode_exit() 4. cros_typec_altmode_exit() attempts to acquire the mutex again This revert is considered safe as no other known driver sends back DP_CMD_STATUS_UPDATE command with the NAK flag. Signed-off-by: Andrei Kuchynski --- drivers/usb/typec/altmodes/displayport.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/a= ltmodes/displayport.c index b09b58d7311d..ac84a6d64c2f 100644 --- a/drivers/usb/typec/altmodes/displayport.c +++ b/drivers/usb/typec/altmodes/displayport.c @@ -393,10 +393,6 @@ static int dp_altmode_vdm(struct typec_altmode *alt, break; case CMDT_RSP_NAK: switch (cmd) { - case DP_CMD_STATUS_UPDATE: - if (typec_altmode_exit(alt)) - dev_err(&dp->alt->dev, "Exit Mode Failed!\n"); - break; case DP_CMD_CONFIGURE: dp->data.conf =3D 0; ret =3D dp_altmode_configured(dp); --=20 2.50.0.rc1.591.g9c95f17f64-goog