From patchwork Wed Jul 29 14:22:46 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ludovic Desroches X-Patchwork-Id: 6894681 Return-Path: X-Original-To: patchwork-linux-mmc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 1459C9F380 for ; Wed, 29 Jul 2015 14:23:50 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4D3852064F for ; Wed, 29 Jul 2015 14:23:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58F0920635 for ; Wed, 29 Jul 2015 14:23:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752820AbbG2OWp (ORCPT ); Wed, 29 Jul 2015 10:22:45 -0400 Received: from eusmtp01.atmel.com ([212.144.249.242]:57897 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750839AbbG2OWn (ORCPT ); Wed, 29 Jul 2015 10:22:43 -0400 Received: from ibiza.corp.atmel.com (10.161.101.13) by eusmtp01.atmel.com (10.161.101.30) with Microsoft SMTP Server id 14.3.235.1; Wed, 29 Jul 2015 16:22:38 +0200 From: Ludovic Desroches To: , , CC: , , , , , Ludovic Desroches Subject: [PATCH v2 1/3] mmc: sdhci: switch from programmable clock mode to divided one if needed Date: Wed, 29 Jul 2015 16:22:46 +0200 Message-ID: <1438179768-818-2-git-send-email-ludovic.desroches@atmel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1438179768-818-1-git-send-email-ludovic.desroches@atmel.com> References: <1438179768-818-1-git-send-email-ludovic.desroches@atmel.com> MIME-Version: 1.0 Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org X-Spam-Status: No, score=-8.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In programmable mode, if the clock frequency is too high, the divider can be too small to meet the clock frequency requirement especially to init the SD card. In this case, switch to the divided clock mode. Signed-off-by: Ludovic Desroches --- drivers/mmc/host/sdhci.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index bc14452..32cf274 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -1152,6 +1152,7 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock) int real_div = div, clk_mul = 1; u16 clk = 0; unsigned long timeout; + bool switch_base_clk = false; host->mmc->actual_clock = 0; @@ -1189,15 +1190,25 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock) <= clock) break; } - /* - * Set Programmable Clock Mode in the Clock - * Control register. - */ - clk = SDHCI_PROG_CLOCK_MODE; - real_div = div; - clk_mul = host->clk_mul; - div--; - } else { + if ((host->max_clk * host->clk_mul / div) <= clock) { + /* + * Set Programmable Clock Mode in the Clock + * Control register. + */ + clk = SDHCI_PROG_CLOCK_MODE; + real_div = div; + clk_mul = host->clk_mul; + div--; + } else { + /* + * Divisor can be too small to reach clock + * speed requirement. Then use the base clock. + */ + switch_base_clk = true; + } + } + + if (!host->clk_mul || switch_base_clk) { /* Version 3.00 divisors must be a multiple of 2. */ if (host->max_clk <= clock) div = 1;