| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Thu, 30 Oct 2014 22:56:33 +0900
From: Alexandre Courbot <gnurou@...il.com>
To: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc: Krzysztof Kozlowski <k.kozlowski@...sung.com>,
Samuel Ortiz <sameo@...ux.intel.com>,
Lee Jones <lee.jones@...aro.org>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Ben Dooks <ben-linux@...ff.org>,
Kukjin Kim <kgene.kim@...sung.com>,
Russell King <linux@....linux.org.uk>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-samsung-soc@...r.kernel.org"
<linux-samsung-soc@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
Kyungmin Park <kyungmin.park@...sung.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Chanwoo Choi <cw00.choi@...sung.com>,
Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH 6/8] regulator: max77686: Add external GPIO control
Hi, and thanks for bringing this issue to us!
On Wed, Oct 29, 2014 at 7:49 PM, Javier Martinez Canillas
<javier.martinez@...labora.co.uk> wrote:
> [adding Linus and Alexandre to the cc list]
>
> Hello Krzysztof,
>
> On 10/29/2014 11:42 AM, Krzysztof Kozlowski wrote:
>> On wto, 2014-10-28 at 13:11 +0100, Krzysztof Kozlowski wrote:
>>> On wto, 2014-10-28 at 09:52 +0100, Krzysztof Kozlowski wrote:
>>> > On pon, 2014-10-27 at 21:03 +0100, Javier Martinez Canillas wrote:
>>> > > Hello Krzysztof,
>>> > >
>>> > > On 10/27/2014 04:03 PM, Krzysztof Kozlowski wrote:
>>> > > > @@ -85,6 +91,9 @@ struct max77686_data {
>>> > > > struct max77686_regulator_data *regulators;
>>> > > > int num_regulators;
>>> > > >
>>> > > > + /* Array of size num_regulators with GPIOs for external control. */
>>> > > > + int *ext_control_gpio;
>>> > > > +
>>> > >
>>> > > The integer-based GPIO API is deprecated in favor of the descriptor-based GPIO
>>> > > interface (Documentation/gpio/consumer.txt). Could you please use the later?
>>> >
>>> > Sure, I can. Please have in mind that regulator core still accepts old
>>> > GPIO so I will have to use desc_to_gpio(). That should work... and
>>> > should be future-ready.
>>>
>>> It seems I was too hasty... I think usage of the new gpiod API implies
>>> completely different bindings.
>>>
>>> The gpiod_get() gets GPIO from a device level, not from given sub-node
>>> pointer. This means that you cannot have DTS like this:
>>> ldo21_reg: ldo21 {
>>> regulator-compatible = "LDO21";
>>> regulator-name = "VTF_2.8V";
>>> regulator-min-microvolt = <2800000>;
>>> regulator-max-microvolt = <2800000>;
>>> ec-gpio = <&gpy2 0 0>;
>>> };
>>>
>>> ldo22_reg: ldo22 {
>>> regulator-compatible = "LDO22";
>>> regulator-name = "VMEM_VDD_2.8V";
>>> regulator-min-microvolt = <2800000>;
>>> regulator-max-microvolt = <2800000>;
>>> ec-gpio = <&gpk0 2 0>;
>>> };
>>>
>>>
>>> I could put GPIOs in device node:
>>>
>>> max77686_pmic@09 {
>>> compatible = "maxim,max77686";
>>> interrupt-parent = <&gpx0>;
>>> interrupts = <7 0>;
>>> reg = <0x09>;
>>> #clock-cells = <1>;
>>> ldo21-gpio = <&gpy2 0 0>;
>>> ldo22-gpio = <&gpk0 2 0>;
>>>
>>> ldo21_reg: ldo21 {
>>> regulator-compatible = "LDO21";
>>> regulator-name = "VTF_2.8V";
>>> regulator-min-microvolt = <2800000>;
>>> regulator-max-microvolt = <2800000>;
>>> };
>>>
>>> ldo22_reg: ldo22 {
>>> regulator-compatible = "LDO22";
>>> regulator-name = "VMEM_VDD_2.8V";
>>> regulator-min-microvolt = <2800000>;
>>> regulator-max-microvolt = <2800000>;
>>> };
>>>
>>> This would work but I don't like it. The properties of a regulator are
>>> above the node configuring that regulator.
>>>
>>> Any ideas?
>>>
>>
>> Continuing talking to myself... I found another problem - GPIO cannot be
>> requested more than once (-EBUSY). In case of this driver (and board:
>> Trats2) one GPIO is connected to regulators. The legacy GPIO API and
>> regulator core handle this.
>>
>> With new GPIO API I would have to implement some additional steps in
>> such case...
>>
>> So there are 2 issues:
>> 1. Cannot put GPIO property in regulator node.
For this problem you will probably want to use the
dev(m)_get_named_gpiod_from_child() function from the following patch:
https://lkml.org/lkml/2014/10/6/529
It should reach -next soon now.
>> 2. Cannot request some GPIO more than once.
We have been confronted to this problem with the regulator core as well:
http://marc.info/?l=linux-arm-kernel&m=140417649119733&w=1
I have a draft patch that allows GPIOs to be requested by several
clients. What prevented me from submitting it was that I wanted to
make sure the different requested configurations were compatible, but
maybe I am overthinking this. There are also a couple of other patches
that this depends on (like removal of the big descs array), so I don't
think it will be available too soon, sadly.
So maybe your best shot for now is to keep using the integer API, as
much as I hate it. Once we become able to request the same GPIO
several times, you should be good to switch to descriptors. Sorry this
has not been done faster.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists