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 25433C433F5 for ; Fri, 18 Mar 2022 12:16:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236102AbiCRMRz (ORCPT ); Fri, 18 Mar 2022 08:17:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236120AbiCRMRu (ORCPT ); Fri, 18 Mar 2022 08:17:50 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F592F2103 for ; Fri, 18 Mar 2022 05:16:32 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 01B5661807 for ; Fri, 18 Mar 2022 12:16:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E47A7C340F2; Fri, 18 Mar 2022 12:16:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1647605791; bh=cMMKH1glzYT8AljESLG2h4PRinA9Pnab7e8fEqonjIw=; h=Subject:To:From:Date:From; b=on1vkpvhw3E9QmfBhMGOUikt9R/etlCvBSezCL37wpEAk2raGuVjV6ZkHnj6Zf8SJ qP1TVb6eFR2GdcE4j/6JAn93X8lgGu6ciZatkg6oTLTeUWuT7N81Qm6J6RD+Kg/0R6 CxX9fOzrxpsBmbxFK45p7+OmuTCkkaw0Zs9WmDyk= Subject: patch "iio: adc: aspeed: Add divider flag to fix incorrect voltage reading." added to char-misc-next 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 12:46:38 +0100 Message-ID: <164760399822299@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-next 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 also be merged in the next major kernel release during the merge window. 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