What does 0x80000000 exactly do in IOMUX CFG ?

[glitch911]

Hi all,

I've been reading with interest this post : understanding iomuxing imx6QD  but can't find the answer ;(

Can you point me to the source of this 0x80000000 value in IOMUX configuration?

More precisely I'd like to know if it's only the PAD_CTL that is unchanged or the MUX_CTL setting as well?

For example MX6QDL_PAD_EIM_D22__GPIO3_IO22 is supposed to set the EIM_D22 PAD as GPIO (ALT5) (#define in imx6q-pinfunc.h) but after changing u-boot to use USB OTG it seems that PAD_EIM_D22 is now configured as USB_OTG_PWR (ALT4) and MX6QDL_PAD_EIM_D22__GPIO3_IO22 0x80000000 seems to do nothing about that after leaving u-boot as I still read 4 when typing devregs 0x020e00a8 (MUX_CTL). For now I need to type "devregs 0x020e00a8 0x5" to get my USB power-supply started. It works but I'd like to understand better why ^^

Any help will be appreciated.

[BiyongSUN]

if you check the code drivers/pinctrl/freescale/pinctrl-imx.c, 0x80000000 will igore to configure the IOMUX and keep the value. And If  0x40000000 to set the SION. 

/* The bits in CONFIG cell defined in binding doc*/
#define IMX_NO_PAD_CTL 0x80000000 /* no pin config need */
#define IMX_PAD_SION 0x40000000  /* set SION */

more explaination.

If you want to add the SION, the original dts like this:

MX6UL_PAD_CSI_DATA01__GPIO4_IO22         0x17059

you need to modify and become

MX6UL_PAD_CSI_DATA01__GPIO4_IO22         0x40017059(0x40000000 |0x17059)

If you want to keep it. Just make  it 0x80000000 is enough.

[igorpadykov]

Hi glitch911

this is linux software convention, not hardware.

Please check linux documentation fsl,imx-pinctrl.txt

linux-imx.git - i.MX Linux Kernel 

Bits used for CONFIG:
NO_PAD_CTL(1 << 31): indicate this pin does not need config.

Best regards
igor
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