[RFC PATCH 2/3] pinctrl: imx: add pinmux-imx53 support

On Mon, Dec 05, 2011 at 10:18:38PM +0100, Sascha Hauer wrote:

On Mon, Dec 05, 2011 at 05:57:42PM +0100, Linus Walleij wrote:

quoted

On Sun, Dec 4, 2011 at 12:49 PM, Dong Aisheng [off-list ref] wrote:

quoted

+enum imx_mx53_pads {
+ ? ? ? MX53_GPIO_19 = 0,
+ ? ? ? MX53_KEY_COL0 = 1,

(...)

First I thought it looked a bit strange since you needed enums for all pads
but then I realized that your macros use the same enumerator name to
name the pad and then it looks sort of clever.

But maybe put in a comment about that here:

quoted

+/* Pad names for the pinmux subsystem */

Like this:

/*
 * Pad names for the pinmux subsystem.
 * These pad names are constructed from the pin enumerator names
 * in the IMX_PINCTRL_PIN() macro.
 */

quoted

+static const struct pinctrl_pin_desc mx53_pads[] = {
+ ? ? ? IMX_PINCTRL_PIN(MX53_GPIO_19),
+ ? ? ? IMX_PINCTRL_PIN(MX53_KEY_COL0),

(...)

quoted

+/* mx53 pin groups and mux mode */
+static const unsigned mx53_fec_pins[] = {
+ ? ? ? MX53_FEC_MDC,
+ ? ? ? MX53_FEC_MDIO,
+ ? ? ? MX53_FEC_REF_CLK,
+ ? ? ? MX53_FEC_RX_ER,
+ ? ? ? MX53_FEC_CRS_DV,
+ ? ? ? MX53_FEC_RXD1,
+ ? ? ? MX53_FEC_RXD0,
+ ? ? ? MX53_FEC_TX_EN,
+ ? ? ? MX53_FEC_TXD1,
+ ? ? ? MX53_FEC_TXD0,
+};

I understand this.

quoted

+static const unsigned mx53_fec_mux[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

But what is this? Just zeroes? Why?
Especially with a const so they really cannot be anything
else. The same pin (0) can only be enumerated once.

quoted

+static const unsigned mx53_sd1_pins[] = {
+ ? ? ? MX53_SD1_CMD,
+ ? ? ? MX53_SD1_CLK,
+ ? ? ? MX53_SD1_DATA0,
+ ? ? ? MX53_SD1_DATA1,
+ ? ? ? MX53_SD1_DATA2,
+ ? ? ? MX53_SD1_DATA3,
+
+};
+static const unsigned mx53_sd1_mux[] = { 0, 0, 0, 0, 0, 0 };

And here again.

quoted

+static const unsigned mx53_sd3_pins[] = {
+ ? ? ? MX53_PATA_DATA8,
+ ? ? ? MX53_PATA_DATA9,
+ ? ? ? MX53_PATA_DATA10,
+ ? ? ? MX53_PATA_DATA11,
+ ? ? ? MX53_PATA_DATA0,
+ ? ? ? MX53_PATA_DATA1,
+ ? ? ? MX53_PATA_DATA2,
+ ? ? ? MX53_PATA_DATA3,
+ ? ? ? MX53_PATA_IORDY,
+ ? ? ? MX53_PATA_RESET_B,
+
+};
+static const unsigned mx53_sd3_mux[] = { 4, 4, 4, 4, 4, 4, 4, 4, 2, 2 };

This also looks strange. Can you explain what these muxes are?

Freescale has named the pins after their primary function which is quite
confusing.

The above means:

MX53_PATA_DATA8 -> mux mode 4
MX53_PATA_DATA9 -> mux mode 4
...

This brings me to the point that currently we have the pins described as

#define MX53_PAD_<name>__<function>

But that's also the reason why we have so many lengthy iomux-mx*.h on
imx.  Taking iomux-mx53.h for example, it's a 109K header with 1219
LOC, but probably only 10% of the definitions will actually be used.

which means that you don't have to look into the datasheet to get the
different options for a pin

Looking at the datasheet when we write code is a pretty natural thing
to me.

-- 
Regards,
Shawn

(and don't have a chance to get it wrong).
I don't really want to lose this.