From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Mon, 14 Apr 2025 13:06:52 +0200 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1u4HeO-000cCe-1U for lore@lore.pengutronix.de; Mon, 14 Apr 2025 13:06:52 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1u4HeN-0008RK-KE for lore@pengutronix.de; Mon, 14 Apr 2025 13:06:52 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=81jEfhE9nQlb0nZavaaG9Fj9HQ9b0uuTzag9q+BTZOQ=; b=Na2f3kBAuh1d2OqPR167DDUa09 368pg0n1nY9Id+Ppz3h1Yy5hFLEiVui9+E1RVxJQGwuy2ew7hdN6N+kCeIKw8/0bC9dt93j1OqqVB d9HOn4DEj5nHPgUincvfWJFQi5ArWGvFFDnSgPMns7g/LQVo9ven0AiQLSOsxezikORClHUoX4PMR fyXAhta6wBMeXDkZ5foSmCspUwAH/pzVi5SoP7Aav50WdLboi2JsYmd9z+27v3EbiCwUdueKCIUlq T1vDxUf4oUJN5jvLHZtQsQj7aL9bcJYUBJ8ZmChIiv2H+1QjB/f7e+M3WjrpkPQ5Ctup+/ZI5a5+j 6uAg2dag==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u4He0-00000001f96-1CVW; Mon, 14 Apr 2025 11:06:28 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u4HUV-00000001cwp-3v9K for barebox@lists.infradead.org; Mon, 14 Apr 2025 10:56:41 +0000 Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1u4HUU-0004ao-HD; Mon, 14 Apr 2025 12:56:38 +0200 Received: from pty.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::c5]) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1u4HUU-000Ehq-0s; Mon, 14 Apr 2025 12:56:38 +0200 Received: from mfe by pty.whiteo.stw.pengutronix.de with local (Exim 4.96) (envelope-from ) id 1u4HUU-000GHl-0a; Mon, 14 Apr 2025 12:56:38 +0200 Date: Mon, 14 Apr 2025 12:56:38 +0200 From: Marco Felsch To: Ahmad Fatoum Cc: barebox@lists.infradead.org, Kim Christensen Message-ID: <20250414105638.uxzlbcigm765uyyg@pengutronix.de> References: <20250414065009.2770749-1-a.fatoum@pengutronix.de> <20250414065009.2770749-4-a.fatoum@pengutronix.de> <20250414084043.j5v2xjh2bnadoicc@pengutronix.de> <20250414092134.glztg7o6nqqsxqdr@pengutronix.de> <7161d8ec-3f19-4504-b9f5-03b512c4f84d@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7161d8ec-3f19-4504-b9f5-03b512c4f84d@pengutronix.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250414_035639_982085_B82B39FA X-CRM114-Status: GOOD ( 37.84 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.2 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH 4/6] ARM: i.MX8MP: skov: halt startup until power is good X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) On 25-04-14, Ahmad Fatoum wrote: > Hello Marco, > > On 14.04.25 11:21, Marco Felsch wrote: > > On 25-04-14, Ahmad Fatoum wrote: > >> Hello Marco, > >> > >> On 14.04.25 10:40, Marco Felsch wrote: > >>> Hi, > >>> > >>> On 25-04-14, Ahmad Fatoum wrote: > >>>> The 24V regulator supplying the system can indicate via a GPIO imminent > >>>> voltage loss. The board's capacitors hold enough charge to power the system > >>>> a while longer in such a state, but eventually, unless external power is > >>>> restored, the brownout detection of the PMIC will kick in. > >>>> > >>>> For the span of time between voltage drop detection and PMIC brownout, > >>>> let's detect this situation and delay startup. This way, Linux can > >>>> detect the ongoing voltage loss, power down the eMMC, reboot into > >>>> barebox and barebox will delay boot as long as the problem persists. > >>>> > >>>> Co-developed-by: Kim Christensen > >>>> Signed-off-by: Ahmad Fatoum > >>>> --- > >>>> arch/arm/boards/skov-imx8mp/lowlevel.c | 60 ++++++++++++++++++++++++++ > >>>> 1 file changed, 60 insertions(+) > >>>> > >>>> diff --git a/arch/arm/boards/skov-imx8mp/lowlevel.c b/arch/arm/boards/skov-imx8mp/lowlevel.c > >>>> index 637fc50b3f30..d7bd771f259d 100644 > >>>> --- a/arch/arm/boards/skov-imx8mp/lowlevel.c > >>>> +++ b/arch/arm/boards/skov-imx8mp/lowlevel.c > >>>> @@ -20,6 +20,9 @@ > >>>> > >>>> extern char __dtb_z_imx8mp_skov_start[]; > >>>> > >>>> +#define PGOOD_PAD_CTRL MUX_PAD_CTRL(MX8MP_PAD_CTL_PUE | \ > >>>> + MX8MP_PAD_CTL_PE) > >>>> + > >>>> #define UART_PAD_CTRL MUX_PAD_CTRL(MX8MP_PAD_CTL_DSE6 | \ > >>>> MX8MP_PAD_CTL_FSEL | \ > >>>> MX8MP_PAD_CTL_PUE | \ > >>>> @@ -30,6 +33,12 @@ extern char __dtb_z_imx8mp_skov_start[]; > >>>> MX8MP_PAD_CTL_PUE | \ > >>>> MX8MP_PAD_CTL_PE) > >>>> > >>>> +static inline void led_d1_toggle(bool *on) > >>>> +{ > >>>> + imx8m_gpio_direction_output(IOMEM(MX8MP_GPIO1_BASE_ADDR), 5, *on); > >>>> + *on = !*on; > >>>> +} > >>>> + > >>>> static void setup_uart(void) > >>>> { > >>>> void __iomem *uart = IOMEM(MX8M_UART2_BASE_ADDR); > >>>> @@ -67,6 +76,55 @@ static struct pmic_config pca9450_cfg[] = { > >>>> { PCA9450_BUCK2OUT_DVS0, 0x14 }, > >>>> }; > >>>> > >>>> +static inline bool power_good(void) > >>>> +{ > >>>> + /* IMX_SHDN_MF in schematics */ > >>>> + return imx8m_gpio_val(IOMEM(MX8MP_GPIO4_BASE_ADDR), 23); > >>>> +} > >>>> + > >>>> +static void wait_for_power_good(void) > >>>> +{ > >>>> + void __iomem *gpio4 = IOMEM(MX8MP_GPIO4_BASE_ADDR); > >>>> + int timeout_ms = 0; > >>>> + bool led_active = true; > >>>> + > >>>> + imx8mp_setup_pad(MX8MP_PAD_SAI2_RXD0__GPIO4_IO23 | PGOOD_PAD_CTRL); > >>>> + imx8m_gpio_direction_input(gpio4, 23); > >>>> + > >>>> + led_d1_toggle(&led_active); > >>>> + > >>>> + if (power_good()) > >>>> + return; > >>>> + > >>>> + pr_warn("\nDelaying boot until power stabilizes\n"); > >>>> + > >>>> + /* If we reach this, because Linux did a hw_protection_reboot, we don't > >>>> + * want to continue booting right away. > >>>> + * > >>>> + * Thus let's either wait for the condition to subscede or for voltage > >>>> + * to reach a low enough level for the PMIC to detect VSYS_UVLO going > >>>> + * lower than allowed > >>>> + */ > >>>> + > >>>> + while (1) { > >>>> + if (power_good()) { > >>>> + /* wait 10ms longer and check if it still good */ > >>>> + udelay(10000); > >>>> + if (power_good()) { > >>>> + pr_info("IMX_SHDN_MF stuck low for ~%ums.\n", timeout_ms); > >>>> + break; > >>>> + } > >>>> + } > >>>> + /* fast blink LED D1 */ > >>>> + if (timeout_ms % 100 == 0) { > >>>> + pr_debug("."); > >>>> + led_d1_toggle(&led_active); > >>>> + } > >>>> + udelay(1000); > >>>> + timeout_ms++; > >>>> + } > >>>> +} > >>>> + > >>>> static void power_init_board(void) > >>>> { > >>>> struct pbl_i2c *i2c; > >>>> @@ -77,6 +135,8 @@ static void power_init_board(void) > >>>> imx8mp_setup_pad(MX8MP_PAD_SAI3_TXD__GPIO5_IO01); > >>>> imx8m_gpio_direction_output(IOMEM(MX8MP_GPIO5_BASE_ADDR), 1, 0); > >>>> > >>>> + wait_for_power_good(); > >>> > >>> out of curiosity, wouldn't it be more useful to do the check right > >>> before the system wants to boot the kernel and abort in that case? > >> > >> How so? > >> > >> When we have brownout, we usually never make it out of the PBL, > > > > Okay, since your backup charge is really low already. > > > >> so I prefer the SoC gets powered off during this loop instead > >> of during the RAM setup. > > > > I understand that to wait for the power to become good again, but what > > if the power is getting good and changes to bad again once you entered > > barebox? Do you get notified about such an event? > > > > IMHO the later point a bit more important since this ensures that the > > system was in power-good state before we the system starts. > > Checking just before booting is insufficient anyway, because power good > may fluctuate before the Linux driver starts taking care of the power > good GPIO. Given that we need to handle this anyway, I don't think > it makes much difference whether when we check the power good GPIO > during barebox runtime. I know, but still it is good to check and to wait for power-good state before you cont. booting. Like you do for barebox: you wait till the power is good or die within the PBL. Regards, Marco > > Cheers, > Ahmad > > > > > Regards, > > Marco > > > > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | >