From patchwork Wed May 11 16:08:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lucas Stach X-Patchwork-Id: 12846412 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 306EEC433F5 for ; Wed, 11 May 2022 16:09:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=EPhkqk/88DM2NRFt5nd2DqW6Kv2vSdNknm220/om+Ns=; b=ClWLvCQgMjVUtv cM6NVvUKmW3nf20RQ3YulDQ0Nkmq6GwWh3L5R/E14PprjEYfIi719HYkkhiDUj5ZNb4FfJ+hfVoJ3 cCZyfR4PxgxxIZ9AZ1J2cG/0R9EhaPSzUxyKGf5WTwtqYZID2JA63tLNkIN42pCFxLZ0VN1DAa1gs PifRxQMp5Ab6Zuxo+NIoPbxr4U8wF7Zzi1EgeHW6FvA+I0WPIBBFGdgww9PPJ+GjqMofkMUMDVUfK q1bYF5ivrs0ThQqsmYRstt+z7zetGDkscdeZk2svVYoMWcYtkHi2QfTjalf154NuNBpP+x+4UxnKo z3xHoj1nSZUBcwm8V0Dg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1noot8-007iLG-L8; Wed, 11 May 2022 16:08:34 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1noot4-007iJx-Vs for linux-arm-kernel@lists.infradead.org; Wed, 11 May 2022 16:08:32 +0000 Received: from dude03.red.stw.pengutronix.de ([2a0a:edc0:0:1101:1d::39]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1noosy-0007GV-Ll; Wed, 11 May 2022 18:08:24 +0200 From: Lucas Stach To: Shawn Guo Cc: Pengutronix Kernel Team , Fabio Estevam , NXP Linux Team , linux-arm-kernel@lists.infradead.org, patchwork-lst@pengutronix.de Subject: [PATCH] ARM: dts: imx6qdl: correct PU regulator ramp delay Date: Wed, 11 May 2022 18:08:23 +0200 Message-Id: <20220511160823.1436562-1-l.stach@pengutronix.de> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2a0a:edc0:0:1101:1d::39 X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-arm-kernel@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220511_090831_060974_4CECB1AB X-CRM114-Status: GOOD ( 16.12 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Contrary to what was believed at the time, the ramp delay of 150us is not plenty for the PU LDO with the default step time of 512 pulses of the 24MHz clock. Measurements have shown that after enabling the LDO the voltage on VDDPU_CAP jumps to ~750mV in the first step and after that the regulator executes the normal ramp up as defined by the step size control. This means it takes the regulator between 360us and 370us to ramp up to the nominal 1.15V voltage for this power domain. With the old setting of the ramp delay the power up of the PU GPC domain would happen in the middle of the regulator ramp with the voltage being at around 900mV. Apparently this was enough for most units to properly power up the peripherals in the domain and execute the reset. Some units however, fail to power up properly, especially when the chip is at a low temperature. In that case any access to the GPU registers would yield an incorrect result with no way to recover from this situation. Change the ramp delay to 380us to cover the measured ramp up time with a bit of additional slack. Fixes: 40130d327f72 ("ARM: dts: imx6qdl: Allow disabling the PU regulator, add a enable ramp delay") Signed-off-by: Lucas Stach --- arch/arm/boot/dts/imx6qdl.dtsi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi index d27beb47f9a3..652feff33496 100644 --- a/arch/arm/boot/dts/imx6qdl.dtsi +++ b/arch/arm/boot/dts/imx6qdl.dtsi @@ -762,7 +762,7 @@ reg_pu: regulator-vddpu { regulator-name = "vddpu"; regulator-min-microvolt = <725000>; regulator-max-microvolt = <1450000>; - regulator-enable-ramp-delay = <150>; + regulator-enable-ramp-delay = <380>; anatop-reg-offset = <0x140>; anatop-vol-bit-shift = <9>; anatop-vol-bit-width = <5>;