From mboxrd@z Thu Jan 1 00:00:00 1970 From: vaibhav.hiremath@linaro.org (Vaibhav Hiremath) Date: Mon, 14 Sep 2015 18:11:36 +0530 Subject: [RFC 2/3] mmc: sdhci: add host_ops->voltage_switch callback for all other voltages In-Reply-To: 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: <55F6C080.8000604@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Monday 14 September 2015 04:04 PM, Ulf Hansson wrote: > 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. Not sure, how I can propagate "call coming from MMC/SD" to both regulator and pinctrl. Probably pinctrl would already know, but then it doesn't know the voltage settings. Let me spend some time, but atleast at this point I am not sure. > > What I don't like is the solution you have suggested in patch3. > As I said, that was easy fit into existing implementation. :) f_sdh30 already does something similar. Thanks, Vaibhav