From: vaibhav.hiremath@linaro.org (Vaibhav Hiremath)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 2/3] mmc: sdhci: add host_ops->voltage_switch callback for all other voltages
Date: Mon, 14 Sep 2015 18:11:36 +0530 [thread overview]
Message-ID: <55F6C080.8000604@linaro.org> (raw)
In-Reply-To: <CAPDyKFrpDPaCLNEdwP7vYM4CJfxyz-zwC8+9AJMcUG+O=GCBOA@mail.gmail.com>
On Monday 14 September 2015 04:04 PM, Ulf Hansson wrote:
> On 14 September 2015 at 11:42, Vaibhav Hiremath
> <vaibhav.hiremath@linaro.org> 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
next prev parent reply other threads:[~2015-09-14 12:41 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-01 19:32 [RFC 0/3] mmc: sdhci: pass signal voltage as an argument to ->voltage_switch() Vaibhav Hiremath
2015-09-01 19:32 ` [RFC 1/3] mmc: sdhci: pass signal_voltage as an argument to voltage_switch callback Vaibhav Hiremath
2015-09-01 19:32 ` [RFC 2/3] mmc: sdhci: add host_ops->voltage_switch callback for all other voltages Vaibhav Hiremath
2015-09-02 7:04 ` Jisheng Zhang
2015-09-02 8:19 ` Vaibhav Hiremath
2015-09-02 8:26 ` Jisheng Zhang
2015-09-02 11:43 ` Vaibhav Hiremath
2015-09-14 9:30 ` Ulf Hansson
2015-09-14 9:42 ` Vaibhav Hiremath
2015-09-14 10:34 ` Ulf Hansson
2015-09-14 12:41 ` Vaibhav Hiremath [this message]
2015-09-14 12:47 ` Vaibhav Hiremath
2015-10-02 10:00 ` Linus Walleij
2015-09-01 19:32 ` [RFC 3/3] mmc: sdhci-pxav3: Add ->voltage_switch callback support Vaibhav Hiremath
[not found] ` <55E6FEF5.9080905@rock-chips.com>
2015-09-02 14:32 ` Vaibhav Hiremath
2015-09-03 18:35 ` Vaibhav Hiremath
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