From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792614709; b=N9V9bRbnA+jy9Bgu1oZLPtOqnzBk3Qp3Ci3vVs9T6lD1hBPHb9a34EI2s3jUNv2AJvzp KSe7o8+8UgUMx0s23eFECTGfk5QacdBWTbwthyhlIQtF7lwuB43S2VmBJ1slxX3xTt/D2 H1O4ZxABGpvWzT2TyV3IIroorCxgLHTzFPKRQF6CbJHHYjDpRHaf9jF2mlPGlIR258xSl qUyvbfxZOx9onD+AcZ+nsbaKtcMFzEZglTIoamwTiF70CapCeOPRFLXV1CbvYyLHZxDjs dJfsG3aQUjkbK6j0SWNkrM+ElS4OtbJ5v+pHuGZL2BICCDl5ZBszxfHLG3zgO2nwW7g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792614709; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=DGBvjIZQK7BbiW5WrZwKGfgW3Pd5/47lDN949Rh8V3Y=; b=u76U256K3DwtaFyFTDUGtuEkPdI8/J1T9429SJJqh8YHY5W3fHsGNr0GByVsxciWPnnB p0/fK74GfSAyCD7JJHzq7UoNYqK8stBt3ke45+tMfh6JjZ0UyLYg4b5Ny85tQMnpOjPVU k7b7m7eyYXZvIw7cSot6LsiH3CteKEq+2CcnmhIx2uzN/c7eMPwb4TikCi0qAfMtDvtUj LEYfJ6cJQTlqXPBhjBAHdNQS36WIoTez6r8XTu953RiuzewIPc5hHchFl5mLj4S4UrNj8 urXU+73jFkyaeRB3pR9bDDQGUCYVv5/+kaY5CRH9c6A4MtI31inTDT5it/YIQ1cIIkA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CRnrTUWT; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F793606A319 for ; Wed, 21 Oct 2026 20:31:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=CRnrTUWT Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4E081F000C1; Wed, 21 Oct 2026 20:31:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792614708; bh=DGBvjIZQK7BbiW5WrZwKGfgW3Pd5/47lDN949Rh8V3Y=; h=From:Subject:Reply-To:To:In-Reply-To:References:Date; b=CRnrTUWTQQEg13oTxCJrGQxG2GYon/odr1FOazpsNI+gFybjPQbfM4JHtFyePeLJe 6RW0YX2TsdTaXh+KtPZeFd9VeS/y8dXIhzMnR1OMQ2vO5pJBHMESouAG76tRbrwsoY 1gzD3202841nqN0817IddzyulmPnIn1Ua/3VL7tu5Y1kXJ0VpnB/S1vtHmhV/X4TOJ zwXmmg+HoG2ixxYh5kRdCaYWHwvLxrDdwPdpV0dypL1PsUA42eLgs+VHm2+1+RurgO 7oFa2hhItilpcIOWgNAt657flJnZ6/LJK47G84eEQTexCuzHR2lSKUxfFBWbcAxMnC ElHMJHRuC2nKQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH] serial: qcom-geni: Set UPSTAT_AUTOCTS for hardware flow control Reply-To: sashiko-reviews@lists.linux.dev To: "Michael McAllister" , linux-serial@vger.kernel.org In-Reply-To: <20261021202603.42888-1-me@michaelmcallister.org> References: <20261021202603.42888-1-me@michaelmcallister.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 21 Oct 2026 20:31:48 +0000 X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > qcom_geni_serial_set_termios() clears UART_CTS_MASK when CRTSCTS is set, > enabling hardware CTS flow control. However, it never sets UPSTAT_AUTOCTS, > so uart_softcts_mode() also selects software-assisted CTS flow control. >=20 > If CTS is deasserted when uart_change_line_settings() samples the modem > status, serial core sets hw_stopped and stops transmission. The GENI > driver does not handle CTS-change interrupts, so asserting CTS again does > not clear hw_stopped or restart the transmitter. >=20 > On a Motorola Moto G10 with WCN3950, this can stall Bluetooth setup in > tty_wait_until_sent() while qca_setup() closes the serial port. A captured > stall had one byte left in the software transmit queue, hw_stopped set, > and CTS asserted, with the UART powered and its interrupt enabled. >=20 > Set UPSTAT_AUTOCTS under the port lock when CRTSCTS is enabled, and clear > it when CRTSCTS is disabled, to match the hardware configuration. >=20 > Fixes: 8a8a66a1a18a ("tty: serial: qcom_geni_serial: Add support for flow= control") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Michael McAllister Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261021202603.4288= 8-1-me@michaelmcallister.org?part=3D1