From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vaibhav Hiremath Subject: Re: [RFC 2/3] mmc: sdhci: add host_ops->voltage_switch callback for all other voltages Date: Mon, 14 Sep 2015 15:12:53 +0530 Message-ID: <55F6969D.7090004@linaro.org> References: <1441135938-8056-1-git-send-email-vaibhav.hiremath@linaro.org> <1441135938-8056-3-git-send-email-vaibhav.hiremath@linaro.org> <20150902150442.118d3305@xhacker> <55E6B129.1030002@linaro.org> <20150902162627.682cdedf@xhacker> <55E6E0FD.7000806@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pa0-f43.google.com ([209.85.220.43]:33739 "EHLO mail-pa0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753097AbbINJm6 (ORCPT ); Mon, 14 Sep 2015 05:42:58 -0400 Received: by pacex6 with SMTP id ex6so140002376pac.0 for ; Mon, 14 Sep 2015 02:42:58 -0700 (PDT) In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Ulf Hansson Cc: Jisheng Zhang , linux-mmc , Linus Walleij , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" On Monday 14 September 2015 03:00 PM, Ulf Hansson wrote: > [...] > >>>>> >>>>> Could this be implemented by regulator API? From patch set 3/3, the >>>>> pxa1928 >>>>> voltage_switch hook is to operate the IO pad registers, this seems not >>>>> belong >>>>> to the SDHC IP core. >>>>> >>>> >>>> Not quite sure whether regulator would be right fit for this. >>> >>> >>> From the patche[3/3], this can be achieved by abstracting the IO PAD as >>> regulators >>> then, we may not need to touch the core sdhci.c. But I'm not sure whether >>> this >>> is the good solution or not. >> >> >> Exactly... >> >>> sdhci Maintainers and experts may have better >>> suggestions. >>> >> >> Thats is the reason I stamped it as a RFC :) >> > > [...] > > From an mmc core perspective it would be preferred if you implement > this as a regulator (vqmmc). > > Especially since we will soon have an API for how to set the I/O > voltages - and the intelligence within that API is not something we > would like to implement for each and every host driver. > https://lkml.org/lkml/2015/8/31/367 > I would still consider this as a regulator specific and may not address the IO configuration within the SoC which are module specific. The API regulator_set_voltage_triplet() will not have intelligence to differentiate whether the call is coming from MMC or somewhere else. Note that, the IO pad voltage configuration which I am referring to is MMC specific and applicable only when pad is configured in MMC mode. So technically it is not simply common pad voltage configuration. And I am still not sure regulator framework would be right fit for this. Pinctrl would have been right fit, but...since I saw f_sdh30 driver is already doing this, which is easy fit; so adopted the same. Thanks, Vaibhav