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 5F0EAC433FE for ; Fri, 18 Mar 2022 11:57:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236012AbiCRL6n (ORCPT ); Fri, 18 Mar 2022 07:58:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236013AbiCRL6l (ORCPT ); Fri, 18 Mar 2022 07:58:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 629502C5425 for ; Fri, 18 Mar 2022 04:57:23 -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 1F372B821D7 for ; Fri, 18 Mar 2022 11:57:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FE8AC340E8; Fri, 18 Mar 2022 11:57:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1647604640; bh=AhMhK8V1zo6/4fMuCLbBxyANSYouqw9SIpx2UHlkl8w=; h=Subject:To:From:Date:From; b=Z3cOzCWknri85zxcIhWXDlTp1NLERZHAw0CMLZi+mMKP28YGFidRGgSCEnSPAPXh2 az06uewSJXPGEOacFGs3w9o5sBE7yYv1vWUpNkaIOltQ5RBqbEglrBa3ZzLzYwHPw+ JgpoXir+Rvfh27WrVmeN6l6jnXK/vVuQ36ZU4/10= Subject: patch "iio: adc: aspeed: Add divider flag to fix incorrect voltage reading." added to char-misc-testing To: billy_tsai@aspeedtech.com, Jonathan.Cameron@huawei.com, Stable@vger.kernel.org, joel@jms.id.au, kitsok@yandex-team.ru From: Date: Fri, 18 Mar 2022 12:43:48 +0100 Message-ID: <1647603828216124@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled iio: adc: aspeed: Add divider flag to fix incorrect voltage reading. to my char-misc git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git in the char-misc-testing branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will be merged to the char-misc-next branch sometime soon, after it passes testing, and the merge window is open. If you have any questions about this process, please let me know. >From 571426631acf46e2999c7ecd1e9d048172969a43 Mon Sep 17 00:00:00 2001 From: Billy Tsai Date: Mon, 21 Feb 2022 09:27:05 +0800 Subject: iio: adc: aspeed: Add divider flag to fix incorrect voltage reading. The formula for the ADC sampling period in ast2400/ast2500 is: ADC clock period = PCLK * 2 * (ADC0C[31:17] + 1) * (ADC0C[9:0]) When ADC0C[9:0] is set to 0 the sampling voltage will be lower than expected, because the hardware may not have enough time to charge/discharge to a stable voltage. This patch use the flag CLK_DIVIDER_ONE_BASED which will use the raw value read from the register, with the value of zero considered invalid to conform to the corrected formula. Fixes: 573803234e72 ("iio: Aspeed ADC") Reported-by: Konstantin Klubnichkin Signed-off-by: Billy Tsai Reviewed-by: Joel Stanley Link: https://lore.kernel.org/r/20220221012705.22008-1-billy_tsai@aspeedtech.com Cc: Signed-off-by: Jonathan Cameron --- drivers/iio/adc/aspeed_adc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c index e939b84cbb56..0793d2474cdc 100644 --- a/drivers/iio/adc/aspeed_adc.c +++ b/drivers/iio/adc/aspeed_adc.c @@ -539,7 +539,9 @@ static int aspeed_adc_probe(struct platform_device *pdev) data->clk_scaler = devm_clk_hw_register_divider( &pdev->dev, clk_name, clk_parent_name, scaler_flags, data->base + ASPEED_REG_CLOCK_CONTROL, 0, - data->model_data->scaler_bit_width, 0, &data->clk_lock); + data->model_data->scaler_bit_width, + data->model_data->need_prescaler ? CLK_DIVIDER_ONE_BASED : 0, + &data->clk_lock); if (IS_ERR(data->clk_scaler)) return PTR_ERR(data->clk_scaler); -- 2.35.1