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 487C31FE468; Tue, 29 Apr 2025 17:03:02 +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=1745946182; cv=none; b=iE8OVH0LViATV5VDLyQpjpDf0Px4k+QSM0ogcH8DpAKDWo20m7LLN09ysS5sx3u3UWu0WQdkNdO8L+rUvhwUCMVQy0xBF1SN0EMmnj50lN1TNIln433HnPGeJx3acZRVaPUzaclvnDs+58kAvAexpikfyTmbb+Cj4pEm/D2O9jY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745946182; c=relaxed/simple; bh=bj22yOdEWtgfS/DW3oPOudE43Qo2v4SfxzjG9TCEZBI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D6YerFi64elGBu+6GoanKf9jTBep0lNRw012kxzAC0oq+cqPgObpLRvqZar3/hNQ8fPwQLTjy2WyAHrRnlHlzAGn3fAi4T7ykfKz2IiqkoT5GBlT63/lRbxXiGqDSg2yQuskgNeumhZxzRx97IsoFtL/53BpOC0DorfbPLisF+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xwOiy/CS; 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="xwOiy/CS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C25FEC4CEE3; Tue, 29 Apr 2025 17:03:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1745946182; bh=bj22yOdEWtgfS/DW3oPOudE43Qo2v4SfxzjG9TCEZBI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xwOiy/CSz5Br2WP8U9FDhpKuHszSARVCJAbYhwEPw7jcYLBQvGpjq7ncGwq2B+xN/ f9WFz+NLOq6rU30jmBg5zV053VUiGM+HcPXSoV3ICQTYp2qCMu0lTi1u/GDDjnGeny rx4u4zIW9YIY2OFd2eJSAnDaLWYsvjgo1fD0s40c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Stephan Gerhold , Neil Armstrong Subject: [PATCH 6.14 153/311] serial: msm: Configure correct working mode before starting earlycon Date: Tue, 29 Apr 2025 18:39:50 +0200 Message-ID: <20250429161127.303537467@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250429161121.011111832@linuxfoundation.org> References: <20250429161121.011111832@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 6.14-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; }