* [PATCH] ARM: iomux-mx51: Always define PUE for pins used as GPIO
@ 2013-05-21 8:27 Alexander Shiyan
2013-05-21 19:24 ` Sascha Hauer
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Shiyan @ 2013-05-21 8:27 UTC (permalink / raw)
To: linux-arm-kernel
This patch adds a PUE bit for pins which used as GPIO. This allow
to use the GPIOs correctly as inputs when source is open-drain with
external pullup resistor (IRQ open-drain outputs for example).
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
---
arch/arm/mach-imx/iomux-mx51.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-imx/iomux-mx51.h b/arch/arm/mach-imx/iomux-mx51.h
index 75bbcc4..7dc187c 100644
--- a/arch/arm/mach-imx/iomux-mx51.h
+++ b/arch/arm/mach-imx/iomux-mx51.h
@@ -34,7 +34,8 @@
#define MX51_SDHCI_PAD_CTRL (PAD_CTL_PKE | PAD_CTL_DSE_HIGH | \
PAD_CTL_PUS_47K_UP | PAD_CTL_PUE | \
PAD_CTL_SRE_FAST | PAD_CTL_DVS)
-#define MX51_GPIO_PAD_CTRL (PAD_CTL_DSE_HIGH | PAD_CTL_PKE | PAD_CTL_SRE_FAST)
+#define MX51_GPIO_PAD_CTRL (PAD_CTL_DSE_HIGH | PAD_CTL_PKE | \
+ PAD_CTL_PUE | PAD_CTL_SRE_FAST)
#define MX51_PAD_CTRL_2 (PAD_CTL_PKE | PAD_CTL_HYS)
#define MX51_PAD_CTRL_3 (PAD_CTL_PKE | PAD_CTL_PUS_100K_UP)
--
1.8.1.5
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH] ARM: iomux-mx51: Always define PUE for pins used as GPIO
2013-05-21 8:27 [PATCH] ARM: iomux-mx51: Always define PUE for pins used as GPIO Alexander Shiyan
@ 2013-05-21 19:24 ` Sascha Hauer
2013-05-22 6:19 ` Alexander Shiyan
0 siblings, 1 reply; 6+ messages in thread
From: Sascha Hauer @ 2013-05-21 19:24 UTC (permalink / raw)
To: linux-arm-kernel
On Tue, May 21, 2013 at 12:27:25PM +0400, Alexander Shiyan wrote:
> This patch adds a PUE bit for pins which used as GPIO. This allow
> to use the GPIOs correctly as inputs when source is open-drain with
> external pullup resistor (IRQ open-drain outputs for example).
I don't understand. If there's an external pullup why do you want to
turn on the internal one?
Sascha
>
> Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
> ---
> arch/arm/mach-imx/iomux-mx51.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-imx/iomux-mx51.h b/arch/arm/mach-imx/iomux-mx51.h
> index 75bbcc4..7dc187c 100644
> --- a/arch/arm/mach-imx/iomux-mx51.h
> +++ b/arch/arm/mach-imx/iomux-mx51.h
> @@ -34,7 +34,8 @@
> #define MX51_SDHCI_PAD_CTRL (PAD_CTL_PKE | PAD_CTL_DSE_HIGH | \
> PAD_CTL_PUS_47K_UP | PAD_CTL_PUE | \
> PAD_CTL_SRE_FAST | PAD_CTL_DVS)
> -#define MX51_GPIO_PAD_CTRL (PAD_CTL_DSE_HIGH | PAD_CTL_PKE | PAD_CTL_SRE_FAST)
> +#define MX51_GPIO_PAD_CTRL (PAD_CTL_DSE_HIGH | PAD_CTL_PKE | \
> + PAD_CTL_PUE | PAD_CTL_SRE_FAST)
>
> #define MX51_PAD_CTRL_2 (PAD_CTL_PKE | PAD_CTL_HYS)
> #define MX51_PAD_CTRL_3 (PAD_CTL_PKE | PAD_CTL_PUS_100K_UP)
> --
> 1.8.1.5
>
>
--
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Industrial Linux Solutions | http://www.pengutronix.de/ |
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] ARM: iomux-mx51: Always define PUE for pins used as GPIO
2013-05-21 19:24 ` Sascha Hauer
@ 2013-05-22 6:19 ` Alexander Shiyan
2013-05-22 7:02 ` [PATCH] ARM: iomux-mx51: Always define PU E " Lothar Waßmann
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Shiyan @ 2013-05-22 6:19 UTC (permalink / raw)
To: linux-arm-kernel
> On Tue, May 21, 2013 at 12:27:25PM +0400, Alexander Shiyan wrote:
> > This patch adds a PUE bit for pins which used as GPIO. This allow
> > to use the GPIOs correctly as inputs when source is open-drain with
> > external pullup resistor (IRQ open-drain outputs for example).
>
> I don't understand. If there's an external pullup why do you want to
> turn on the internal one?
It is just switch off keeper circuit.
Some pads not have internal pullup, probably this is affected only for such pins.
This is example of this issue:
Used pad MX51_PAD_DISPB2_SER_CLK__GPIO3_7, (GPIO3.7 = 71).
External pullup resistor is used.
gpio_direction output 71 1
gpio_direction_input 71
gpio_get_value 71; echo $?
1
gpio_direction output 71 0
gpio_direction_input 71
gpio_get_value 71; echo $?
0
So, we cannot get "1" here anymore if only pullup is used for this pad. The pad is keep last logic state...
The second solution for this is disable PKE, i am not sure which solution is the best...
> > Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
> > ---
> > arch/arm/mach-imx/iomux-mx51.h | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/mach-imx/iomux-mx51.h b/arch/arm/mach-imx/iomux-mx51.h
> > index 75bbcc4..7dc187c 100644
> > --- a/arch/arm/mach-imx/iomux-mx51.h
> > +++ b/arch/arm/mach-imx/iomux-mx51.h
> > @@ -34,7 +34,8 @@
> > #define MX51_SDHCI_PAD_CTRL (PAD_CTL_PKE | PAD_CTL_DSE_HIGH | \
> > PAD_CTL_PUS_47K_UP | PAD_CTL_PUE | \
> > PAD_CTL_SRE_FAST | PAD_CTL_DVS)
> > -#define MX51_GPIO_PAD_CTRL (PAD_CTL_DSE_HIGH | PAD_CTL_PKE | PAD_CTL_SRE_FAST)
> > +#define MX51_GPIO_PAD_CTRL (PAD_CTL_DSE_HIGH | PAD_CTL_PKE | \
> > + PAD_CTL_PUE | PAD_CTL_SRE_FAST)
> >
> > #define MX51_PAD_CTRL_2 (PAD_CTL_PKE | PAD_CTL_HYS)
> > #define MX51_PAD_CTRL_3 (PAD_CTL_PKE | PAD_CTL_PUS_100K_UP)
> > --
---
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] ARM: iomux-mx51: Always define PU E for pins used as GPIO
2013-05-22 6:19 ` Alexander Shiyan
@ 2013-05-22 7:02 ` Lothar Waßmann
2013-05-22 7:17 ` Re[3]: " Alexander Shiyan
0 siblings, 1 reply; 6+ messages in thread
From: Lothar Waßmann @ 2013-05-22 7:02 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
Alexander Shiyan writes:
> > On Tue, May 21, 2013 at 12:27:25PM +0400, Alexander Shiyan wrote:
> > > This patch adds a PUE bit for pins which used as GPIO. This allow
> > > to use the GPIOs correctly as inputs when source is open-drain with
> > > external pullup resistor (IRQ open-drain outputs for example).
> >
> > I don't understand. If there's an external pullup why do you want to
> > turn on the internal one?
>
> It is just switch off keeper circuit.
>
If you want to switch the keeper circuit off why don't you do that by
removing PAD_CTL_PKE rather than adding PAD_CTL_PUE?
Lothar Wa?mann
--
___________________________________________________________
Ka-Ro electronics GmbH | Pascalstra?e 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Gesch?ftsf?hrer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996
www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re[3]: [PATCH] ARM: iomux-mx51: Always define PU E for pins used as GPIO
2013-05-22 7:02 ` [PATCH] ARM: iomux-mx51: Always define PU E " Lothar Waßmann
@ 2013-05-22 7:17 ` Alexander Shiyan
2013-05-22 8:36 ` Lothar Waßmann
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Shiyan @ 2013-05-22 7:17 UTC (permalink / raw)
To: linux-arm-kernel
> Alexander Shiyan writes:
> > > On Tue, May 21, 2013 at 12:27:25PM +0400, Alexander Shiyan wrote:
> > > > This patch adds a PUE bit for pins which used as GPIO. This allow
> > > > to use the GPIOs correctly as inputs when source is open-drain with
> > > > external pullup resistor (IRQ open-drain outputs for example).
> > >
> > > I don't understand. If there's an external pullup why do you want to
> > > turn on the internal one?
> >
> > It is just switch off keeper circuit.
> >
> If you want to switch the keeper circuit off why don't you do that by
> removing PAD_CTL_PKE rather than adding PAD_CTL_PUE?
Again, I do not know which the solution here is better. If we remove
the PKE bit, for some pins it will be removed the default pullup/pulldown (PUS = 0),
so it may affect the some running configuration.
---
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] ARM: iomux-mx51: Always define PU E for pins used as GPIO
2013-05-22 7:17 ` Re[3]: " Alexander Shiyan
@ 2013-05-22 8:36 ` Lothar Waßmann
0 siblings, 0 replies; 6+ messages in thread
From: Lothar Waßmann @ 2013-05-22 8:36 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
Alexander Shiyan writes:
> > Alexander Shiyan writes:
> > > > On Tue, May 21, 2013 at 12:27:25PM +0400, Alexander Shiyan wrote:
> > > > > This patch adds a PUE bit for pins which used as GPIO. This allow
> > > > > to use the GPIOs correctly as inputs when source is open-drain with
> > > > > external pullup resistor (IRQ open-drain outputs for example).
> > > >
> > > > I don't understand. If there's an external pullup why do you want to
> > > > turn on the internal one?
> > >
> > > It is just switch off keeper circuit.
> > >
> > If you want to switch the keeper circuit off why don't you do that by
> > removing PAD_CTL_PKE rather than adding PAD_CTL_PUE?
>
> Again, I do not know which the solution here is better. If we remove
> the PKE bit, for some pins it will be removed the default pullup/pulldown (PUS = 0),
> so it may affect the some running configuration.
>
IMO the current approach of defining the pad config with the pad
definition is broken anyway. It would be much better to specify the
pad configuration at the point where a specific pad is used, rather
than where it is defined.
The pin mux setting for a specific function of a pin is always the
same for any platform but the pad config may be different for
different platforms.
Lothar Wa?mann
--
___________________________________________________________
Ka-Ro electronics GmbH | Pascalstra?e 22 | D - 52076 Aachen
Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10
Gesch?ftsf?hrer: Matthias Kaussen
Handelsregistereintrag: Amtsgericht Aachen, HRB 4996
www.karo-electronics.de | info at karo-electronics.de
___________________________________________________________
^ permalink raw reply [flat|nested] 6+ messages in thread
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2013-05-21 8:27 [PATCH] ARM: iomux-mx51: Always define PUE for pins used as GPIO Alexander Shiyan
2013-05-21 19:24 ` Sascha Hauer
2013-05-22 6:19 ` Alexander Shiyan
2013-05-22 7:02 ` [PATCH] ARM: iomux-mx51: Always define PU E " Lothar Waßmann
2013-05-22 7:17 ` Re[3]: " Alexander Shiyan
2013-05-22 8:36 ` Lothar Waßmann
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