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,URIBL_BLOCKED,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 208E4C072B1 for ; Thu, 30 May 2019 03:39:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB0F224BA8 for ; Thu, 30 May 2019 03:39:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559187577; bh=/1/VuPTBjvJK3nvRAXGIG9xM6xaswXAxFD8bHJwTYGg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Fc9ay0fl4ECs3RndIQvRiH2glSA4Yt3qRWALrMuDMfX65dpPuvCSpzCuQTjxbP1oY foCo0WaSMD+kVFaN+cQWqoakQIync2cbLXv57PKw3dpgBvNlDPOsnaYkyvmHZmzTXI zLbDi2pLiRfaqqs3ALH1iIK+i94Q4Iqc3GTJltbk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732100AbfE3DWH (ORCPT ); Wed, 29 May 2019 23:22:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:42876 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730720AbfE3DQe (ORCPT ); Wed, 29 May 2019 23:16:34 -0400 Received: from localhost (ip67-88-213-2.z213-88-67.customer.algx.net [67.88.213.2]) (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 8E9E3245FE; Thu, 30 May 2019 03:16:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186193; bh=/1/VuPTBjvJK3nvRAXGIG9xM6xaswXAxFD8bHJwTYGg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jIKHJt694H65RTC/1h3YOjCvzDnKTInI1tlREhoRK0JpQb040rx6ANtTVuDfhKcWG St4P43L45oZbnrIHrq/Vit5Hnkk02qSbnxgMiGjODHCVChYib7jZgfPR57M2kCrmx/ MVJZ0yYyATEbyai1bVeamnzKQHCcaIdBzx6fMz2s= 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 4.19 066/276] spi: pxa2xx: fix SCR (divisor) calculation Date: Wed, 29 May 2019 20:03:44 -0700 Message-Id: <20190530030530.114938733@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190530030523.133519668@linuxfoundation.org> References: <20190530030523.133519668@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 b624f6fb04ce5..729be74621e37 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -876,10 +876,14 @@ 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