Messages in this thread | | | Date | Fri, 11 Jul 2014 02:51:40 +0200 | From | Javier Martinez Canillas <> | Subject | Re: [PATCH v7 08/24] mfd: max77686: Add Dynamic Voltage Scaling (DVS) support |
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Hello Linus,
On 07/10/2014 11:46 AM, Linus Walleij wrote: > On Fri, Jul 4, 2014 at 10:24 PM, Javier Martinez Canillas > <javier.martinez@collabora.co.uk> wrote: > >> Some regulators on the MAX77686 PMIC have Dynamic Voltage Scaling >> (DVS) support that allows output voltage to change dynamically. >> >> For MAX77686, these regulators are Buck regulators 2, 3 and 4. >> >> Each Buck output voltage is selected using a set of external >> inputs: DVS1-3 and SELB2-4. >> >> DVS registers can be used to configure the output voltages for each >> Buck regulator and which one is active is controled by DVSx lines. >> >> SELBx lines are used to control if individual Buck lines are ON or OFF. >> >> This patch adds support to configure the DVSx and SELBx lines >> from DT and to setup and read the GPIO lines connected to them. >> >> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> >> Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > > (...) >> +#include <linux/gpio/consumer.h> > > THANKS for using modern interfaces! >
Thanks to you and Alexandre for keep improving the GPIO subsystem!
>> +static void max77686_dt_parse_dvs_gpio(struct device *dev) >> +{ >> + struct max77686_platform_data *pd = dev_get_platdata(dev); >> + int i; >> + >> + /* >> + * NOTE: we don't consider GPIO errors fatal; board may have some lines >> + * directly pulled high or low and thus doesn't specify them. >> + */ >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_dvs); i++) >> + pd->buck_gpio_dvs[i] = >> + devm_gpiod_get_index(dev, "max77686,pmic-buck-dvs", i); >> + >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++) >> + pd->buck_gpio_selb[i] = >> + devm_gpiod_get_index(dev, "max77686,pmic-buck-selb", i); >> +} > > Rob Jones has a patch cooking that adds gpio_get_array() so this thing > merits also adding devm_gpiod_get_array() I think? >
Yes, I just asked [0] Rob on the other thread if he is already implementing the descriptor-based version of his devm_request_gpio_array() or if I should go and implement it.
Now, I wonder if that can be done in a follow-up patch (e.g: use the new devm_gpiod_get_array once it lands in Torvalds tree) since this series already touches several subsystems (mfd, regulators, clk and rtc) so if possible I would prefer to not add another cross-subsystem dependency :)
>> +/** >> + * max77686_setup_gpios() - init DVS-related GPIOs >> + * @dev: device whose platform data contains the dvs GPIOs information >> + * >> + * This function claims / initalizations GPIOs related to DVS if they are >> + * defined. This may have the effect of switching voltages if the >> + * pdata->buck_default_idx does not match the boot time state of pins. >> + */ >> +int max77686_setup_gpios(struct device *dev) >> +{ >> + struct max77686_platform_data *pd = dev_get_platdata(dev); >> + int buck_default_idx = pd->buck_default_idx; >> + int ret; >> + int i; >> + >> + /* Set all SELB high to avoid glitching while DVS is changing */ >> + for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++) { >> + struct gpio_desc *gpio = pd->buck_gpio_selb[i]; >> + >> + /* OK if some GPIOs aren't defined */ >> + if (IS_ERR(gpio)) >> + continue; >> + >> + ret = gpiod_direction_output_raw(gpio, 1); > > Why does this have to be raw? Usually that is not to be used. >
Right, I can't think of a good reason why this has to be raw and not just use gpiod_direction_output() which will check the active-low flag and set the value accordingly. I'll change it on the next revision.
> Apart from this it looks OK. >
Great, thanks a lot for your feedback.
> Yours, > Linus Walleij >
Best regards, Javier
[0]: https://lkml.org/lkml/2014/7/10/722
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