Hello,
on an i.MX25 machine on my desk a UART RX line is guarded by a transistor
like this:
,------------------------.
| ,---------. |
| | imx25 o--RX----◁---o---
| | o--GPIO--' |
| `---------' |
`------------------------'
The reason is that the reset default setting of the pin in question
(MX25_PAD_LBA) is driving the line. So after switching the pad to its
UART function the gpio must be driven to make the transistor
transparent.
My first idea was to make this a property of the UART and added a
enable-gpios property for it[1]. But now I wonder if this is better
abstracted as an enable-gpios property in the pinctrl node. Something
like:
pinctrl_uart5: uart5 {
fsl,pins = <
MX25_PAD_ECB__UART5_TXD 0x00002080 /* TXD */
MX25_PAD_LBA__UART5_RXD 0x00000000 /* RXD */
MX25_PAD_CS4__UART5_CTS 0x00002001 /* RTS */
MX25_PAD_CS5__GPIO_3_21 0x00002001 /* #RXD_EN */
>;
enable-gpios = <&gpio3 21 GPIO_ACTIVE_LOW>;
};
Would this make sense? Maybe with a more intuitive name?
Best regards
Uwe
[1] http://patchwork.ozlabs.org/patch/647787/
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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