From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Rozhkov Subject: [PATCH] mmc: Adjust timings for power ramping up Date: Mon, 13 Aug 2012 19:19:21 +0300 Message-ID: <20120813161921.GA5022@x230> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from smtp154.iad.emailsrvr.com ([207.97.245.154]:45237 "EHLO smtp154.iad.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752241Ab2HMQ0i (ORCPT ); Mon, 13 Aug 2012 12:26:38 -0400 Content-Disposition: inline Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Chris Ball Cc: linux-mmc@vger.kernel.org According to p6.4.1.1 of the Physical Layer Simplified Specification Ver3.01 the "host needs to keep power line level less than 0.5V and more than 1ms before power ramp up". This patch adds an explicit delay of 10ms just before power rump up. Without this patch some microSD cards (e.g. Kingston 8G Class 10) can't be used as bootable media on some TI OMAP chips at least. See https://bugs.nemomobile.org/show_bug.cgi?id=92 for details. Signed-off-by: Dmitry Rozhkov --- drivers/mmc/core/core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 0b6141d..22b0eb2 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -1163,6 +1163,13 @@ static void mmc_power_up(struct mmc_host *host) mmc_host_clk_hold(host); + /* + * According to p6.4.1.1 of the Physical Layer Simplified Specification + * Ver3.01 the "host needs to keep power line level less than 0.5V and + * more than 1ms before power ramp up". + */ + mmc_delay(10); + /* If ocr is set, we use it */ if (host->ocr) bit = ffs(host->ocr) - 1; -- 1.7.9.5