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 ECEF82528EC; Tue, 29 Apr 2025 17:31:20 +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=1745947881; cv=none; b=F3f2ypvRCVuE/EPSaiGjG8fLlguUnCLv56tK6zxApQk/jERhnCpSw/h5AV+ESdtgs/e8261uBlQomzrBOyolfIdp+CSo2jvtSBtlX5TnWmVcKWZ/gu2G4QCDes41aijL0tZHdXppv4iVJzESfXYxDAtBuL2Ru+63pvN+RqxJVyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745947881; c=relaxed/simple; bh=4iVPUqiQSRt2ne+u8W5jW6QOsCqohMfuZxeM4K1qiFw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=h5wVdK14JvctC6t2LSngneZCblimEaW56VgRPEs49xliuVM6H7F3Ix5UTBjqa4U1olT9r6uO3yShNxlRDZAJdBmmRc3P2Cegyu34r27Sv9WuTkHo+eX8wCvASKQ5YQi2v9OBEbf4YsSZ4jllqKH6o4UYLikqKQqFsRP8asR/efw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h7ZnjHSa; 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="h7ZnjHSa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04F9FC4CEE3; Tue, 29 Apr 2025 17:31:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1745947880; bh=4iVPUqiQSRt2ne+u8W5jW6QOsCqohMfuZxeM4K1qiFw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h7ZnjHSam5M1/hIsAp8xfvdJ6aCbfL2EKLWfCBNdKwC6vtplG77IlPxNhlnM4DWPx Vd5G8zrQe6cCAoUB0Sx9MneXj7qSDzZkqSpnhOyofYFST0eH6tQpFc8FJdt2U0zyMJ igGVD4tfno1yPbsfsEBfcPTmDZOaMefK0ty3w5rc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Stephan Gerhold , Neil Armstrong Subject: [PATCH 6.12 131/280] serial: msm: Configure correct working mode before starting earlycon Date: Tue, 29 Apr 2025 18:41:12 +0200 Message-ID: <20250429161120.487128090@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250429161115.008747050@linuxfoundation.org> References: <20250429161115.008747050@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephan Gerhold commit 7094832b5ac861b0bd7ed8866c93cb15ef619996 upstream. The MSM UART DM controller supports different working modes, e.g. DMA or the "single-character mode", where all reads/writes operate on a single character rather than 4 chars (32-bit) at once. When using earlycon, __msm_console_write() always writes 4 characters at a time, but we don't know which mode the bootloader was using and we don't set the mode either. This causes garbled output if the bootloader was using the single-character mode, because only every 4th character appears in the serial console, e.g. "[ 00oni pi 000xf0[ 00i s 5rm9(l)l s 1 1 SPMTA 7:C 5[ 00A ade k d[ 00ano:ameoi .Q1B[ 00ac _idaM00080oo'" If the bootloader was using the DMA ("DM") mode, output would likely fail entirely. Later, when the full serial driver probes, the port is re-initialized and output works as expected. Fix this also for earlycon by clearing the DMEN register and reset+re-enable the transmitter to apply the change. This ensures the transmitter is in the expected state before writing any output. Cc: stable Fixes: 0efe72963409 ("tty: serial: msm: Add earlycon support") Signed-off-by: Stephan Gerhold Reviewed-by: Neil Armstrong Link: https://lore.kernel.org/r/20250408-msm-serial-earlycon-v1-1-429080127530@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/msm_serial.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -1746,6 +1746,12 @@ msm_serial_early_console_setup_dm(struct if (!device->port.membase) return -ENODEV; + /* Disable DM / single-character modes */ + msm_write(&device->port, 0, UARTDM_DMEN); + msm_write(&device->port, MSM_UART_CR_CMD_RESET_RX, MSM_UART_CR); + msm_write(&device->port, MSM_UART_CR_CMD_RESET_TX, MSM_UART_CR); + msm_write(&device->port, MSM_UART_CR_TX_ENABLE, MSM_UART_CR); + device->con->write = msm_serial_early_write_dm; return 0; }