From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 1/3] mmc: add support for power-on sequencing through DT Date: Sat, 15 Feb 2014 14:09:39 +0100 Message-ID: <1580658.FIe4en5bEU@wuerfel> References: <1390190215-22700-1-git-send-email-olof@lixom.net> <3871646.18hjUjnpmg@wuerfel> <20140215122733.GK30257@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.186]:50804 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753050AbaBONJy (ORCPT ); Sat, 15 Feb 2014 08:09:54 -0500 In-Reply-To: <20140215122733.GK30257@n2100.arm.linux.org.uk> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: linux-arm-kernel@lists.infradead.org Cc: Russell King - ARM Linux , mark.rutland@arm.com, devicetree@vger.kernel.org, Ulf Hansson , Pawel Moll , Ian Campbell , Tomasz Figa , linux-mmc , Tomasz Figa , Chris Ball , robh+dt@kernel.org, Kumar Gala , Olof Johansson , Fabio Estevam , Sascha Hauer On Saturday 15 February 2014 12:27:33 Russell King - ARM Linux wrote: > On Sat, Feb 15, 2014 at 01:18:02PM +0100, Arnd Bergmann wrote: > > If a wlan adapter has both SPI and SDIO front-ends, the external > > dependencies (reset, clock, voltage, ...) will be the same, and > > from the kernel perspective the main difference is that SPI cannot > > be probed at all, while SDIO can be probed as long as the device > > is powered on already. > > Remember that MMC/SD/SDIO cards can be driven by either a MMC host > interface, or a SPI interface. Both are probe-able. I knew about MMC/SD cards being required to understand simple SPI, I wasn't sure about SDIO. My understanding however is that you have to use the mmc_spi host driver to actually use MMC/SD devices as a block device, and that requires having either a DT description for the host or an spi_board_info, which I would not consider discoverable. For spi-mode SDIO devices I'm assuming it's similar, except that you'd describe the actual SDIO device in the board info rather than create a fake SDIO controller. Still not discoverable unless I'm missing your point. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Sat, 15 Feb 2014 14:09:39 +0100 Subject: [PATCH 1/3] mmc: add support for power-on sequencing through DT In-Reply-To: <20140215122733.GK30257@n2100.arm.linux.org.uk> References: <1390190215-22700-1-git-send-email-olof@lixom.net> <3871646.18hjUjnpmg@wuerfel> <20140215122733.GK30257@n2100.arm.linux.org.uk> Message-ID: <1580658.FIe4en5bEU@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Saturday 15 February 2014 12:27:33 Russell King - ARM Linux wrote: > On Sat, Feb 15, 2014 at 01:18:02PM +0100, Arnd Bergmann wrote: > > If a wlan adapter has both SPI and SDIO front-ends, the external > > dependencies (reset, clock, voltage, ...) will be the same, and > > from the kernel perspective the main difference is that SPI cannot > > be probed at all, while SDIO can be probed as long as the device > > is powered on already. > > Remember that MMC/SD/SDIO cards can be driven by either a MMC host > interface, or a SPI interface. Both are probe-able. I knew about MMC/SD cards being required to understand simple SPI, I wasn't sure about SDIO. My understanding however is that you have to use the mmc_spi host driver to actually use MMC/SD devices as a block device, and that requires having either a DT description for the host or an spi_board_info, which I would not consider discoverable. For spi-mode SDIO devices I'm assuming it's similar, except that you'd describe the actual SDIO device in the board info rather than create a fake SDIO controller. Still not discoverable unless I'm missing your point. Arnd