From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3F05C11F64 for ; Mon, 28 Jun 2021 19:16:13 +0000 (UTC) Received: from phobos.denx.de (phobos.denx.de [85.214.62.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1AC816191B for ; Mon, 28 Jun 2021 19:16:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1AC816191B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gerhold.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Received: from h2850616.stratoserver.net (localhost [IPv6:::1]) by phobos.denx.de (Postfix) with ESMTP id 0718282E09; Mon, 28 Jun 2021 21:16:11 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=none (p=none dis=none) header.from=gerhold.net Authentication-Results: phobos.denx.de; spf=pass smtp.mailfrom=u-boot-bounces@lists.denx.de Authentication-Results: phobos.denx.de; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gerhold.net header.i=@gerhold.net header.b="hoQ8TI26"; dkim-atps=neutral Received: by phobos.denx.de (Postfix, from userid 109) id 0E05C82E0B; Mon, 28 Jun 2021 21:16:09 +0200 (CEST) Received: from mo4-p00-ob.smtp.rzone.de (mo4-p00-ob.smtp.rzone.de [85.215.255.21]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by phobos.denx.de (Postfix) with ESMTPS id 9C81C82DFC for ; Mon, 28 Jun 2021 21:16:05 +0200 (CEST) Authentication-Results: phobos.denx.de; dmarc=none (p=none dis=none) header.from=gerhold.net Authentication-Results: phobos.denx.de; spf=none smtp.mailfrom=stephan@gerhold.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1624907765; s=strato-dkim-0002; d=gerhold.net; h=In-Reply-To:References:Message-ID:Subject:Cc:To:From:Date:Cc:Date: From:Subject:Sender; bh=7B6vZCXZ9minUqHLSfD3kDgkSJZNbPVLa0XkTcuplSM=; b=hoQ8TI26X3WR6Ooo+xaf9wfvubqoASZalCF9xPutH9heNS/1yqWHyp2fF55+WZ9sYY Fn8DDQbBbczaQnSyJmt62635OFaU5YiWagQiCSiVvDRh22AMD55rffHJQpgueV4pQSBc SNdjrCNLL/Irn9SwkzRE1zAGWcgMAL6HbpK2hYkdBDq7oiSCLc9e0Vy3r5a5mhDxUnJb iAgtkQcFshRACU8sgpJCWx4chOPjP5mW+aEU4+ZCaojRlDrgPoGLvNUbIrK+rSItQ7p6 /oGdkzYuOIBxortFt2oIcjNvcTJFHWJWokJPRJn1do7GSIpWyUPKAxezMiCvPrYP4s1w XQaw== Authentication-Results: strato.com; dkim=none X-RZG-AUTH: ":P3gBZUipdd93FF5ZZvYFPugejmSTVR2nRPhVOQ/OcYgojyw4j34+u26zEodhPgRDZ8f6IczEaIo=" X-RZG-CLASS-ID: mo00 Received: from gerhold.net by smtp.strato.de (RZmta 47.27.5 DYNA|AUTH) with ESMTPSA id m02a28x5SJG5VLJ (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Mon, 28 Jun 2021 21:16:05 +0200 (CEST) Date: Mon, 28 Jun 2021 21:16:00 +0200 From: Stephan Gerhold To: Ramon Fried Cc: U-Boot Mailing List Subject: Re: [PATCH] serial: serial_msm: Ensure BAM/single character mode are disabled Message-ID: References: <20210628084009.3098-1-stephan@gerhold.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.34 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" X-Virus-Scanned: clamav-milter 0.103.2 at phobos.denx.de X-Virus-Status: Clean On Mon, Jun 28, 2021 at 10:04:29PM +0300, Ramon Fried wrote: > On Mon, Jun 28, 2021 at 9:59 PM Stephan Gerhold wrote: > > > > On Mon, Jun 28, 2021 at 08:15:28PM +0300, Ramon Fried wrote: > > > On Mon, Jun 28, 2021 at 11:40 AM Stephan Gerhold wrote: > > > > > > > > At the moment, the U-Boot serial_msm driver does not initialize the > > > > UART_DM_DMEN register with the required value. Usually this does not > > > > cause any problems, because there is Qualcomm's LK bootloader running > > > > before U-Boot which initializes the register with the correct value. > > > > > > > > It's important that this register is initialized correctly, because > > > > the U-Boot driver does not make use of the BAM/DMA or single character > > > > mode functionality of the UART controller. A different bootloader > > > > before U-Boot might initialize the register differently. > > > > > > > > For example, on DragonBoard 410c U-Boot can also be installed to the > > > > "aboot" partition (replacing LK entirely). In this case U-Boot is > > > > loaded directly by SBL, which seems to use the single-character mode > > > > for some reason. In single character mode there is always just one > > > > char in the FIFO, instead of the 4 characters expected by > > > > msm_serial_fetch(). It also causes issues with "earlycon" later in > > > > the Linux kernel, which tries to output 4 chars at once, > > > > but only the first char will be written. > > > > > > > > This causes early UART log in Linux to be corrupted like this: > > > > > > > > [ 00ano:ameoi .Q1B[ 00ac _idaM00080oo'ahani-lcle._20). 15NdNii 5 SPMSJ20:U2 > > > > [ 00rkoolmsamel > > > > [ 00Fw ]elamletopsioble > > > > [ 00ore > > > > > > > > instead of > > > > > > > > [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd030] > > > > [ 0.000000] Machine model: Qualcomm Technologies, Inc. APQ 8016 SBC > > > > [ 0.000000] earlycon: msm_serial_dm0 at MMIO 0x00000000078b0000 (options '') > > > > [ 0.000000] printk: bootconsole [msm_serial_dm0] enabled > > > > > > > > Make sure to initialize UART_DM_DMEN correctly to fix this issue > > > > when loading U-Boot directly after SBL (instead of through LK). > > > > > > > > There is no functional difference when loading U-Boot through LK > > > > since LK also initializes UART_DM_DMEN to 0x0. [1] > > > > > > > > [1]: https://git.linaro.org/landing-teams/working/qualcomm/lk.git/tree/platform/msm_shared/uart_dm.c?h=dragonboard410c-LA.BR.1.2.7-03810-8x16.0-linaro3#n203 > > > > > > > > Cc: Ramon Fried > > > > Signed-off-by: Stephan Gerhold > > > > --- > > > > > > > > drivers/serial/serial_msm.c | 4 ++++ > > > > 1 file changed, 4 insertions(+) > > > > > > > > diff --git a/drivers/serial/serial_msm.c b/drivers/serial/serial_msm.c > > > > index d8c6c2f6b5..d8dd5c1104 100644 > > > > --- a/drivers/serial/serial_msm.c > > > > +++ b/drivers/serial/serial_msm.c > > > > @@ -23,6 +23,7 @@ > > > > /* Serial registers - this driver works in uartdm mode*/ > > > > > > > > #define UARTDM_DMRX 0x34 /* Max RX transfer length */ > > > > +#define UARTDM_DMEN 0x3C /* DMA/data-packing mode */ > > > > #define UARTDM_NCF_TX 0x40 /* Number of chars to TX */ > > > > > > > > #define UARTDM_RXFS 0x50 /* RX channel status register */ > > > > @@ -197,6 +198,9 @@ static void uart_dm_init(struct msm_serial_data *priv) > > > > writel(MSM_BOOT_UART_DM_8_N_1_MODE, priv->base + UARTDM_MR2); > > > > writel(MSM_BOOT_UART_DM_CMD_RESET_RX, priv->base + UARTDM_CR); > > > > writel(MSM_BOOT_UART_DM_CMD_RESET_TX, priv->base + UARTDM_CR); > > > > + > > > > + /* Make sure BAM/single character mode is disabled */ > > > > + writel(0x0, priv->base + UARTDM_DMEN); > > > > } > > > > static int msm_serial_probe(struct udevice *dev) > > > > { > > > > -- > > > > 2.32.0 > > > > > > > Hi. > > > This is strange, I never encountered the behaviour, and I did boot > > > Linux after U-boot without LK in the way. > > > > It happens for me if the boot flow is SBL -> U-Boot -> Linux instead of > > SBL -> LK -> U-Boot -> Linux (The latter is the suggested setup > > according to dragonboard410c_defconfig and the dragonboard410c > > readme.txt, but I wanted to eliminate LK entirely). > > > > If you tried the same, perhaps you didn't have earlycon enabled? > > It also happens only during early boot with earlycon enabled > > ("earlycon" in kernel parameters). It stops happening later on boot > > when the kernel fully re-initializes the UART controller. (The idea of > > earlycon is to reuse the existing UART configuration to report errors > > that occur very early during boot.) > > > > Thanks, > > Stephan > It's interesting, I wanted to eliminate LK entirely, but I encountered > an error I couldn't understand. > You can run U-boot compiled to 64bit and 32bit, in 64bit the boot is > stuck for some reason, and Tom refused to merge a patch where a 32bit > U-boot would boot a 64bit Linux. > Did you compile U-boot for 64 or 32 ? How far did you get ? Ah, right. I run U-Boot in 64-bit mode. But I think I'm familiar with the problem you are talking about (Linux getting stuck when booting U-Boot directly in 64-bit mode). Basically it's a bug in the PSCI implementation on DragonBoard 410c (part of the TrustZone/tz firmware). Unless you have *something* that triggers the 32-bit -> 64-bit switch via the TZ syscalls, the PSCI implementation will boot all other CPU cores in 32-bit mode (since it does not know the switch to 64-bit has occurred). I have a workaround for this in my open-source "hyp" firmware replacement for DB410c: https://github.com/msm8916-mainline/qhypstub (The README has further detailed information about the bug and the workaround, it's a bit hard to explain shortly...) If you use this "hyp" firmware it shouldn't get stuck anymore. As another nice side effect both U-Boot and Linux will start in EL2 so you can use KVM or other hypervisors. :) Stephan