From patchwork Tue Mar 7 15:32:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 660402 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F98FC678D5 for ; Tue, 7 Mar 2023 15:33:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231302AbjCGPd2 (ORCPT ); Tue, 7 Mar 2023 10:33:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231318AbjCGPdI (ORCPT ); Tue, 7 Mar 2023 10:33:08 -0500 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B88677E786 for ; Tue, 7 Mar 2023 07:32:51 -0800 (PST) Received: by mail-pl1-x631.google.com with SMTP id i10so14474088plr.9 for ; Tue, 07 Mar 2023 07:32:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1678203171; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=oAaIzsWI+DXQ807RCKvS+zEYcv/H3X+nOpua3UqPND8=; b=c+U7tgYtMbvwsqogjSKc1e3jIlbaa2okhG0YBUKZ+/YpKGgJjzUmnneyowcxRJm6DW 6jRthk68ytVUzM6sh77z9yVlZ5e5B8aQ/MoNxhzWxjPegCa/OgwXJGGSl/BLJRDTvUrz SIWK4/R9Du0ulewEUbp9nuwXkJNeU36Yux5/o= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678203171; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=oAaIzsWI+DXQ807RCKvS+zEYcv/H3X+nOpua3UqPND8=; b=XAu+O5zeQ4zMykVriQ83GKQfucukdlSZUjEPQUGsYIKd//7fPhXdwlYUni8W795FPr 1VOKh4eQ39fCd8kC1a7Sb2MdpwIgJdrWLQTgrJO2AKGvWbCt+gOU1+EucE0vwpHkfo8H jhjhMID3Ov4M6mkdMTKEiK5EV3rs1sZtEbxPhv61Inakli+dhtYiKP/R0otv9dEbluxt x+6yI1SMmp4Gd+MOzGDCiX9h/nuyNGW36++ZLoNQV/GU/Y5b8vuHnDStFLZV7hRXw9/F Uguepb52n/FxwT+YPfcD1zxmNf1dp7cZteWjvQnhbIL2X40pi8b80BUlR7MumuBy1zkQ ksLw== X-Gm-Message-State: AO0yUKVSVSKhMrijIzwz0mwHQwz2cOIdggW+2SjHA2xYbhVJrKGo3H35 iDo/S948jVM/xM5+OuxpgfW+GA== X-Google-Smtp-Source: AK7set9YT+h+URl5z9jkarOCmjqbanYlcXm3N10vAqJLY2v22NAZ3Ao9oO5SaoI6/ADUBN1+wljhtQ== X-Received: by 2002:a17:903:1c9:b0:19e:6fd5:f4fa with SMTP id e9-20020a17090301c900b0019e6fd5f4famr15192866plh.69.1678203171195; Tue, 07 Mar 2023 07:32:51 -0800 (PST) Received: from tictac2.mtv.corp.google.com ([2620:15c:9d:2:2023:7dda:98bb:96dd]) by smtp.gmail.com with ESMTPSA id jy16-20020a17090342d000b0019719f752c5sm8586843plb.59.2023.03.07.07.32.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Mar 2023 07:32:50 -0800 (PST) From: Douglas Anderson To: Bjorn Andersson , Greg Kroah-Hartman Cc: Jiri Slaby , Bartosz Golaszewski , Daniel Thompson , linux-serial@vger.kernel.org, linux-arm-msm@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, Konrad Dybcio , Douglas Anderson , Andy Gross , linux-kernel@vger.kernel.org Subject: [PATCH 3/3] tty: serial: qcom-geni-serial: Add a poll_init() function Date: Tue, 7 Mar 2023 07:32:13 -0800 Message-Id: <20230307073155.3.Ie678853bb101091afe78cc8c22344bf3ff3aed74@changeid> X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog In-Reply-To: <20230307073155.1.Iaab0159b8d268060a0e131ebb27125af4750ef99@changeid> References: <20230307073155.1.Iaab0159b8d268060a0e131ebb27125af4750ef99@changeid> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On sc7180 Chromebooks, I did the following: * Didn't enable earlycon in the kernel command line. * Didn't enable serial console in the kernel command line. * Didn't enable an agetty or any other client of "/dev/ttyMSM0". * Added "kgdboc=ttyMSM0" to the kernel command line. After I did that, I tried to enter kdb with this command over an ssh session: echo g > /proc/sysrq-trigger When I did that the system just hung. Although I thought I'd tested this scenario before, I couldn't go back and find a time when it was working. Previous testing must have relied on either the UART acting as the kernel console or an agetty running. It turns out to be pretty easy to fix: we can just use qcom_geni_serial_port_setup() as the .poll_init() function. This, together with the patch ("serial: uart_poll_init() should power on the UART"), allows the debugger to work even if there are no other users of the serial port. Signed-off-by: Douglas Anderson --- drivers/tty/serial/qcom_geni_serial.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index 74a0e074c2de..00752ff783c6 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -1534,6 +1534,7 @@ static const struct uart_ops qcom_geni_console_pops = { #ifdef CONFIG_CONSOLE_POLL .poll_get_char = qcom_geni_serial_get_char, .poll_put_char = qcom_geni_serial_poll_put_char, + .poll_init = qcom_geni_serial_port_setup, #endif .pm = qcom_geni_serial_pm, };