From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753143Ab2ILIuT (ORCPT ); Wed, 12 Sep 2012 04:50:19 -0400 Received: from na3sys009aog118.obsmtp.com ([74.125.149.244]:41748 "EHLO na3sys009aog118.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751865Ab2ILIuO (ORCPT ); Wed, 12 Sep 2012 04:50:14 -0400 MIME-Version: 1.0 In-Reply-To: <1346764151-21323-1-git-send-email-gururaja.hebbar@ti.com> References: <1346764151-21323-1-git-send-email-gururaja.hebbar@ti.com> From: "S, Venkatraman" Date: Wed, 12 Sep 2012 14:19:51 +0530 Message-ID: Subject: Re: [PATCH] mmc: omap_hsmmc: Enable HSPE bit for high speed cards To: "Hebbar, Gururaja" Cc: linux-omap@vger.kernel.org, linux-mmc@vger.kernel.org, rob.herring@calxeda.com, linux-kernel@vger.kernel.org, grant.likely@secretlab.ca, cjb@laptop.org, nsekhar@ti.com, sudhakar.raj@ti.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 4, 2012 at 6:39 PM, Hebbar, Gururaja wrote: > HSMMC IP on AM33xx need a special setting to handle High-speed cards. > Other platforms like TI81xx, OMAP4 may need this as-well. This depends > on the HSMMC IP timing closure done for the high speed cards. > > From AM335x TRM (SPRUH73F - 18.3.12 Output Signals Generation) > > The MMC/SD/SDIO output signals can be driven on either falling edge or > rising edge depending on the SD_HCTL[2] HSPE bit. This feature allows > to reach better timing performance, and thus to increase data transfer > frequency. > > There are few pre-requisites for enabling the HSPE bit > - Controller should support High-Speed-Enable Bit and > - Controller should not be using DDR Mode and > - Controller should advertise that it supports High Speed in > capabilities register and > - MMC/SD clock coming out of controller > 25MHz > The patch is well written. But then, I don't see a need for a DT binding for this feature. By definition, HS implies 25MHz or above, so that check seems to be redundant as well. Meanwhile, I'll check with HSPE enabled on OMAP. Regards, Venkat.