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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53EADC28EBD for ; Sun, 9 Jun 2019 17:02:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A7262084A for ; Sun, 9 Jun 2019 17:02:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560099722; bh=tZGW0O4B71ivYIO4FCWfayaaq1AbrrdZlUq/R9EoRiM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rs2RoOOh+o/2goZKT6n+Q0Le7ps7p2RpCDQWC8+pna+RrdBNaFiUjiuOhSJXlHtCg P0FH99rbvufyUMiKJqg6hnyfRZvmlpdrgWjhBQ21K+A4iM+HixoYyD5McPXaDaY4sU 42kSVzIxlx/TbxFXlkRGwKWnqK1pFgo6lgJPOdJY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388181AbfFIRCA (ORCPT ); Sun, 9 Jun 2019 13:02:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:39600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388169AbfFIRB6 (ORCPT ); Sun, 9 Jun 2019 13:01:58 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BF996206C3; Sun, 9 Jun 2019 17:01:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560099718; bh=tZGW0O4B71ivYIO4FCWfayaaq1AbrrdZlUq/R9EoRiM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DuBF8oS2l4CdK2VgmcKRIWZFdt8un4cxrM8iSalT3yykbui1O/TKw4VmxXTI7pm0D xeZ5YNu6K+/K5NED4xHubFwyeliVTUmtuv0c4p6FrHM6j+Le9qK6KEXmwQlnJhTKsF 9RwXY2839g8sKf1eyZU/E1Ya9Ddw2P2ot1Cxhmvk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Flavio Suligoi , Jarkko Nikula , Mark Brown , Sasha Levin Subject: [PATCH 4.4 098/241] spi: pxa2xx: fix SCR (divisor) calculation Date: Sun, 9 Jun 2019 18:40:40 +0200 Message-Id: <20190609164150.623363353@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190609164147.729157653@linuxfoundation.org> References: <20190609164147.729157653@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit 29f2133717c527f492933b0622a4aafe0b3cbe9e ] Calculate the divisor for the SCR (Serial Clock Rate), avoiding that the SSP transmission rate can be greater than the device rate. When the division between the SSP clock and the device rate generates a reminder, we have to increment by one the divisor. In this way the resulting SSP clock will never be greater than the device SPI max frequency. For example, with: - ssp_clk = 50 MHz - dev freq = 15 MHz without this patch the SSP clock will be greater than 15 MHz: - 25 MHz for PXA25x_SSP and CE4100_SSP - 16,56 MHz for the others Instead, with this patch, we have in both case an SSP clock of 12.5MHz, so the max rate of the SPI device clock is respected. Signed-off-by: Flavio Suligoi Reviewed-by: Jarkko Nikula Reviewed-by: Jarkko Nikula Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-pxa2xx.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c index 3cac73e4c3e4a..e87b6fc9f4c63 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -859,10 +859,14 @@ static unsigned int ssp_get_clk_div(struct driver_data *drv_data, int rate) rate = min_t(int, ssp_clk, rate); + /* + * Calculate the divisor for the SCR (Serial Clock Rate), avoiding + * that the SSP transmission rate can be greater than the device rate + */ if (ssp->type == PXA25x_SSP || ssp->type == CE4100_SSP) - return (ssp_clk / (2 * rate) - 1) & 0xff; + return (DIV_ROUND_UP(ssp_clk, 2 * rate) - 1) & 0xff; else - return (ssp_clk / rate - 1) & 0xfff; + return (DIV_ROUND_UP(ssp_clk, rate) - 1) & 0xfff; } static unsigned int pxa2xx_ssp_get_clk_div(struct driver_data *drv_data, -- 2.20.1