From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manoharan Vijaya Raghavan Subject: TI OMAP4430 - UHS support Date: Mon, 24 Oct 2011 08:56:07 +0000 (UTC) Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from lo.gmane.org ([80.91.229.12]:48450 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752355Ab1JXJAI (ORCPT ); Mon, 24 Oct 2011 05:00:08 -0400 Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1RIGO6-00039h-Tt for linux-omap@vger.kernel.org; Mon, 24 Oct 2011 11:00:07 +0200 Received: from 125.19.39.117 ([125.19.39.117]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 24 Oct 2011 11:00:06 +0200 Received: from thenewsymbol by 125.19.39.117 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 24 Oct 2011 11:00:06 +0200 Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: linux-omap@vger.kernel.org Hi, I need your help in writing a UHS-I driver for OMAP4430. I would like to know the feasibility in implementing a UHS-I driver (for SD card) in OMAP4430. (I am using Pandaboard). The purpose is to have readspeed more than 40MB/s for SD cards (Which as per the SD card specification 3.01 is possible only in UHS-I mode). For this I see that OMAP4430 supports 1.8V and DDR50 mode also. Please let me know your informed opinion about whether UHS-I can be implemented for Pandaboard. I am having trouble in switching to UHS-I mode in Pandaboard. Following are my queries. I am using an SD card which does support UHS-I mode. (Sandisk UHS Extreme Pro (45 MB/s quoted speed)) I am trying to switch the card to UHS mode by first sending a ACMD41. For this I have modified the mmc_send_app_op_cond () in drivers/mmc/core/sd_ops.c to set the S18R bit. And in the response from the SD card I see that S18A bit is set. After this response response from the SD Card I am sending CMD11 to SD Card. After receiving the response from SD Card I am changing the SDVS in MMCHS_HCTL to 0x5 which is for 1.8V.(As per mentioned in the Specification). However I am not able to read the DLEV as 0xF from PSTATE register as per mentioned in the OMAP4430 specification. Please let me know what I might be missing. Is there is a possbility that we could achieve 40MB/s of read speed in SD mode without using the UHS-I ? We see in the spec that it does support upto 48MB/s in DDR mode. But as per the SD card specification 3.01 DDR mode is supported only in UHS-I mode. This is the reason I am trying to switch the card to UHS-I mode. Please let me know if there is a way to use DDR mode in Pandaboard for SD card without having to switch to UHS-I to achieve read speeds of around 40MB/s. with thanks, V.Manoharan