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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 3B70FC282CE for ; Wed, 22 May 2019 19:36:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0E39520675 for ; Wed, 22 May 2019 19:36:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553814; bh=irppVcgwRVsmn8gpyfP7T1YSfDasC28ynChgPB5Zhbk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=t19mWVsrQ9yc4JJSeHwxKzpKRElyQnt3tOtSyB7pnd9nmz1Zf0VoSD7m3MjZUlYOV dIY67BNsT3JpyAyYdtE3df4FJTBOySbHZf8tw2KiKYFZkwYdApKj2PfQE9NYjADwRI M0qYXQ1fI6RMLb31pzbgfrq5iKq7jQWkM3L+ruyg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732971AbfEVTgx (ORCPT ); Wed, 22 May 2019 15:36:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:54036 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733269AbfEVTae (ORCPT ); Wed, 22 May 2019 15:30:34 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 303C4217D7; Wed, 22 May 2019 19:30:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553433; bh=irppVcgwRVsmn8gpyfP7T1YSfDasC28ynChgPB5Zhbk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A9zhMOO+JWUk8lO82hr1UMjS9dFnoShYmO+2diNKjMn/pPDmavec51LC8seAcy0XE QjQnkB/gqHbMNM9WDYPXUlniNS1wkRJGYs7IM61iRhxcuyAOucKAFQyvHhYU1nuN0Y 80CkhfKOiWxkNsBVzA4a6fT3ajZ02TPKKltblci4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Flavio Suligoi , Jarkko Nikula , Mark Brown , Sasha Levin , linux-spi@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 010/114] spi: pxa2xx: fix SCR (divisor) calculation Date: Wed, 22 May 2019 15:28:33 -0400 Message-Id: <20190522193017.26567-10-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190522193017.26567-1-sashal@kernel.org> References: <20190522193017.26567-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Flavio Suligoi [ 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 f2209ec4cb68d..8b618f0fa459f 100644 --- a/drivers/spi/spi-pxa2xx.c +++ b/drivers/spi/spi-pxa2xx.c @@ -921,10 +921,14 @@ 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