I apologize in advance for my bad English.
Problem Description Control USB Power on the device TL-MR3420v2.
Exactly found that the Power switch USB port controlled by GPIO4, but
the ability to control this GPIO4 (in output mode) - does not allow.
Are known patches that manage GPIO4 in Input mode, so it can somehow
enable USB-Power switch.
My doubts about that I wrote in https://dev.openwrt.org/ticket/13201#comment:18
In the original firmware source code found that USB-port powered GPIO4
in Output mode (USB_POWER_ON = "1").
> static int usb_power_write (struct file *file, const char *buf,
> unsigned long count, void *data)
> {
> u_int32_t val = 0;
>
> if (sscanf(buf, "%d", &val) != 1)
> return -EINVAL;
>
> if ((val < 0) || (val > 1))
> return -EINVAL;
>
> printk("%s %d: write gpio:value = %d\r\n",__FUNCTION__,__LINE__,val);
>
> if (USB_POWER_ON == val)
> {
> ath_gpio_out_val(USB_POWER_SW_GPIO, USB_POWER_ON);
> }
> else
> {
> ath_gpio_out_val(USB_POWER_SW_GPIO, USB_POWER_OFF);
> }
>
> return count;
> }
ap123_gpl/ap123/linux/kernels/mips-linux-2.6.31/arch/mips/atheros/gpio.c
However, the actual change with this configuration OpenWRT - there is
no positive result and GPIO4 not controlled.
Also known that with this configuration OpenWRT does not work
USB-LED. In the original firmware source code revealed that it is
controlled by a negative value of "0" = enabled.
> /* USB LED, default is GPIO11 */
> #define AP_USB_LED_GPIO CONFIG_GPIO_USB_LED_BIT
> /* USB LED's value when off */
> #define USB_LED_OFF (!CONFIG_GPIO_USB_LED_ON)
> /* USB LED's value when on, default is 0 */
> #define USB_LED_ON CONFIG_GPIO_USB_LED_ON
ap123_gpl/ap123/linux/kernels/mips-linux-2.6.31/arch/mips/atheros/gpio.c
But in this configuration OpenWRT USB-LED default active_low = "1"
I have some thoughts on that.
In the GPL-source code for the AP123 platform I do not find the
initial configuration of GPIO at uboot level. Most likely this is
because it was moved to the level of firmware (compared with other
platforms TP-Link). At least this applies to GPIO4 - where exactly in
the source "gpio.c" disable AR934X_GPIO_FUNC_CLK_OBS4_EN (BIT (6)).
> /* config gpio15, 14, 11, 4, 16, 17 as normal gpio function */
> /* gpio4 */
> ath_reg_rmw_clear(ATH_GPIO_FUNCTIONS, 1<<6);
> ath_reg_rmw_clear(ATH_GPIO_OUT_FUNCTION1, 0xff);
> /* gpio11 */
> ath_reg_rmw_clear(ATH_GPIO_OUT_FUNCTION2, 0xff<<24);
> /* gpio14 */
> ath_reg_rmw_clear(ATH_GPIO_OUT_FUNCTION3, 0xff<<16);
> /* gpio15 */
> ath_reg_rmw_clear(ATH_GPIO_OUT_FUNCTION3, 0xff<<24);
> /* gpio16 */
> ath_reg_rmw_clear(ATH_GPIO_OUT_FUNCTION4, 0xff<<0);
> /* gpio17 */
> ath_reg_rmw_clear(ATH_GPIO_OUT_FUNCTION4, 0xff<<8);
ap123_gpl/ap123/linux/kernels/mips-linux-2.6.31/arch/mips/atheros/gpio.c
I ask to speak up about my comments.
GPL source code can be downloaded at link:
http://www.tp-link.com/en/support/gpl/?categoryid=547
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