From: Michael Trimarchi <michael@amarulasolutions.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH] gpio: spear_gpio: Fix gpio_set_value() implementation
Date: Fri, 21 Jun 2013 08:42:50 +0200 [thread overview]
Message-ID: <51C3F5EA.2050506@amarulasolutions.com> (raw)
In-Reply-To: <51C3D94D.1030507@st.com>
On 06/21/2013 06:40 AM, Vipin Kumar wrote:
> On 6/20/2013 7:26 PM, Axel Lin wrote:
>> 2013/6/20 Marek Vasut<marex@denx.de>
>>>
>>> Dear Axel Lin,
>>>
>>>> In current gpio_set_value() implementation, it always sets the gpio control
>>>> bit no matter the value argument is 0 or 1. Thus the GPIOs never set to
>>>> low. This patch fixes this bug.
>>>>
>>>> Signed-off-by: Axel Lin<axel.lin@ingics.com>
>>>> ---
>>>> drivers/gpio/spear_gpio.c | 5 ++++-
>>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpio/spear_gpio.c b/drivers/gpio/spear_gpio.c
>>>> index d3c728e..8878608 100644
>>>> --- a/drivers/gpio/spear_gpio.c
>>>> +++ b/drivers/gpio/spear_gpio.c
>>>> @@ -52,7 +52,10 @@ int gpio_set_value(unsigned gpio, int value)
>>>> {
>>>> struct gpio_regs *regs = (struct gpio_regs *)CONFIG_GPIO_BASE;
>>>>
>>>> - writel(1<< gpio,®s->gpiodata[DATA_REG_ADDR(gpio)]);
>>>> + if (value)
>>>> + writel(1<< gpio,®s->gpiodata[DATA_REG_ADDR(gpio)]);
>>>> + else
>>>> + writel(0,®s->gpiodata[DATA_REG_ADDR(gpio)]);
>>>
>>> How can this possibly work? Writing 0 to the whole bank will unset all the
>>> GPIOs, no ?
>>
>>
>> Because each GPIO is controlled by a register.
>> And only one bit will be set when set gpio to high.
>>
>> So it's safe to write 0 for clearing the bit.
>>
>> Note, the gpio_get_value() implementation also assumes there is only one bit
>> will be set. ( If this is not true, both gpio_get_value() and gpio_set_value()
>> need fix.)
>>
>> Vipin, can you review this patch and confirm this behavior?
>>
>
> Yes this is right. and the code is fine
>
The problem is not in set one bit but in reset one bit. Can you check
the else path?
Michael
> Regards
> Vipin
>
>> Thanks,
>> Axel
>> .
>>
>
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot
next prev parent reply other threads:[~2013-06-21 6:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 7:13 [U-Boot] [PATCH] gpio: spear_gpio: Fix gpio_set_value() implementation Axel Lin
2013-06-20 7:22 ` Stefan Roese
2013-06-20 13:09 ` Michael Trimarchi
2013-06-20 13:57 ` Marek Vasut
2013-06-20 15:04 ` Michael Trimarchi
2013-06-20 15:11 ` Marek Vasut
2013-06-20 13:44 ` Marek Vasut
2013-06-20 13:56 ` Axel Lin
2013-06-20 20:02 ` Michael Trimarchi
2013-06-20 20:16 ` Marek Vasut
2013-06-21 4:40 ` Vipin Kumar
2013-06-21 6:42 ` Michael Trimarchi [this message]
2013-06-30 4:18 ` Axel Lin
2013-06-30 8:10 ` Michael Trimarchi
2013-06-30 8:57 ` Axel Lin
2013-07-01 4:27 ` Vipin Kumar
2013-07-01 5:32 ` Axel Lin
2013-07-01 6:21 ` Vipin Kumar
2013-08-12 16:57 ` Axel Lin
2013-08-12 17:00 ` Michael Trimarchi
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