[PATCH 1/4] ARM: mx53: Add pads for flexcan pins

[Uwe Kleine-König]

On Thu, Sep 08, 2011 at 01:30:09PM -0300, Rogerio Pimentel wrote:
> 2011/9/6 Uwe Kleine-König <u.kleine-koenig at pengutronix.de>:
> ...
> >>  #define PAD_CTRL_I2C (PAD_CTL_SRE_FAST | PAD_CTL_ODE | PAD_CTL_PKE | \
> >>                       PAD_CTL_PUE | PAD_CTL_DSE_HIGH | PAD_CTL_PUS_100K_UP \
> >>                       | PAD_CTL_HYS)
> >> +#define MX53_CAN_PAD_CTRL    (PAD_CTL_PKE | PAD_CTL_PUE | PAD_CTL_DSE_HIGH | \
> >> +                                     PAD_CTL_HYS)
> >> +#define MX53_PAD_CTRL_1      (PAD_CTL_PKE | PAD_CTL_PUE | PAD_CTL_DSE_HIGH | \
> >> +                                     PAD_CTL_HYS | PAD_CTL_PUS_100K_UP)
> > Hmm, isn't there a better name for this define? Maybe
> > MX53_CAN_RX_PAD_CTRL and MX53_CAN_TX_PAD_CTRL?
> 
> CAN_RX uses a common pad config that will be used on further pin
> configs, so I think it will be redundant if I create two defines with
> the same config. You can see some other pins configured using
> MX53_PAD_CTRL_1 on Freescale Kernel:
> http://opensource.freescale.com/git?p=imx/linux-2.6-imx.git;a=blob;f=arch/arm/plat-mxc/include/mach/iomux-mx53.h;h=4f28c0f48d299bf7b4399f964c433205549aba2d;hb=imx_2.6.35
> ...
Just because they use the same value it doesn't necessary mean they
should use a single symbol IMHO. Defines are about readability, not minimal
number of SLOC.

> >>  #define _MX53_PAD_GPIO_19__KPP_COL_5         IOMUX_PAD(0x348, 0x20, 0, 0x840, 0, 0)
> >>  #define _MX53_PAD_GPIO_19__GPIO4_5           IOMUX_PAD(0x348, 0x20, 1, 0x0, 0, 0)
> >> @@ -1243,14 +1247,14 @@
> >>  #define MX53_PAD_KEY_ROW1__USBPHY1_RXVALID           (_MX53_PAD_KEY_ROW1__USBPHY1_RXVALID | MUX_PAD_CTRL(NO_PAD_CTRL))
> >>  #define MX53_PAD_KEY_COL2__KPP_COL_2         (_MX53_PAD_KEY_COL2__KPP_COL_2 | MUX_PAD_CTRL(NO_PAD_CTRL))
> >>  #define MX53_PAD_KEY_COL2__GPIO4_10          (_MX53_PAD_KEY_COL2__GPIO4_10 | MUX_PAD_CTRL(NO_PAD_CTRL))
> >> -#define MX53_PAD_KEY_COL2__CAN1_TXCAN                (_MX53_PAD_KEY_COL2__CAN1_TXCAN | MUX_PAD_CTRL(NO_PAD_CTRL))
> >> +#define MX53_PAD_KEY_COL2__CAN1_TXCAN                (_MX53_PAD_KEY_COL2__CAN1_TXCAN | MUX_PAD_CTRL(MX53_PAD_CTRL_1))
> > I wonder if this change is universal. If an external pull-up is
> > assembled using MX53_CAN_PAD_CTRL would be fine? (Note, I don't know if
> > it is sensible to do so.)
> 
> At least on i.MX53 ARD board an internal pull up is used without any
> pull up resistor on the board. It avoids an extra component on board.
Yeah, this doesn't answer if it's universal to include the pullup in the
pad config. I didn't check, but if there are alternative pull strength,
is 100k universal?

I don't know the mx53 pinmux stuff too well, but if it's not hard to add
the pull up only in the machine file, I'd prefer that.

Best regards
Uwe

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