From mboxrd@z Thu Jan 1 00:00:00 1970 From: ulf.hansson@linaro.org (Ulf Hansson) Date: Mon, 14 Sep 2015 12:34:32 +0200 Subject: [RFC 2/3] mmc: sdhci: add host_ops->voltage_switch callback for all other voltages In-Reply-To: <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> <55F6969D.7090004@linaro.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 14 September 2015 at 11:42, Vaibhav Hiremath wrote: > > > 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. Pinctrl would work as well, or perhaps a combination of both pinctrl and a regulator. What I don't like is the solution you have suggested in patch3. Kind regards Uffe