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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D9C6C43334 for ; Mon, 27 Jun 2022 11:45:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237666AbiF0LpS (ORCPT ); Mon, 27 Jun 2022 07:45:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237409AbiF0Lmt (ORCPT ); Mon, 27 Jun 2022 07:42:49 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CEF06F14; Mon, 27 Jun 2022 04:37:29 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 8491BB8111B; Mon, 27 Jun 2022 11:37:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00A9EC3411D; Mon, 27 Jun 2022 11:37:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656329847; bh=N7dJWLRMRxzL2biPyLakUYQmTOEGugbKkPbjLBE8LRU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MFIJY5FwhMS64NdD+P1fg4mOyGZnuG/98jKSWtPJOyNocPBT83k18dKt41DJJGu9a 252H/U5Y3mH1hWYs4kdUsY5y8SEALnA7FAvus3KneU/dZIyvnVGAmcH7fPFcu11vOr uh+R1619BgU3e/yyOAMKzeTBffTIhmajxHI7/r/c= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lucas Stach , Shawn Guo Subject: [PATCH 5.15 122/135] ARM: dts: imx6qdl: correct PU regulator ramp delay Date: Mon, 27 Jun 2022 13:22:09 +0200 Message-Id: <20220627111941.695258314@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220627111938.151743692@linuxfoundation.org> References: <20220627111938.151743692@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lucas Stach commit 93a8ba2a619816d631bd69e9ce2172b4d7a481b8 upstream. 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 Signed-off-by: Shawn Guo Signed-off-by: Greg Kroah-Hartman --- arch/arm/boot/dts/imx6qdl.dtsi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/arm/boot/dts/imx6qdl.dtsi +++ b/arch/arm/boot/dts/imx6qdl.dtsi @@ -763,7 +763,7 @@ 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>;