UART4 registration to linux kernel

Hello Parimala,

You configure the cernel to register 3 UART devices, right?  I think that the problem is as follows:
According to OMAP4460 TRM, Section 23.3.1 UART/IrDA/CIR Overview, the device contains four UART devices controlled by the MPU:
• Three UART-only modules (UART1, UART2, and UART4) are pinned out for use as UART devices
only.
• UART3, which adds infrared communication support, is pinned out for use as a UART, IrDA, or CIR
device, and can be programmed to any available operating mode.

Typically UART3 is used as IrDA interface, so when configureing CONFIG_SERIAL_8250_NR_UARTS & CONFIG_SERIAL_8250_RUNTIME_UARTS to 3 you register UART1, UART2 and UART4 devices.

Best Regards,
Yordan

Hello Yordan,

Thank you for the reply.

If I give CONFIG_SERIAL_8250_RUNTIME_UARTS & CONFIG_SERIAL_8250_NR_UARTS to 2 also all the 4 uarts gets registered during kernel boot. following is the boot log

[    0.729522] Serial: 8250/16550 driver, 2 ports, IRQ sharing enabled
[    0.730773] omap_uart.0: ttyO0 at MMIO 0x4806a000 (irq = 104) is a OMAP UART0
[    0.731231] omap_uart.1: ttyO1 at MMIO 0x4806c000 (irq = 105) is a OMAP UART1
[    0.731719] omap_uart.2: ttyO2 at MMIO 0x48020000 (irq = 106) is a OMAP UART2
[    1.779205] console [ttyO2] enabled
[    1.783386] omap_uart.3: ttyO3 at MMIO 0x4806e000 (irq = 102) is a OMAP UART3

and "cat /proc/iomem" too shows memory allocations for all the UARTS.

Why the kernel configurations are ineffective in this case?

Regards,

Parimala

Hello Parimala,

You are making these modifications to kernel/arch/arm/configs/android_omap_defconfig, right?

Also, which OS are you using (my guess is Android)?

Best Regards,

Yordan

Hello Yordan,

I am using Linux OS, not the Android.

I have a pandaboard es hardware and I am doing the following steps to compile linux kernel

make omap4plus_defconfig

make menuconfig(to configure number of UARTS)

make uImage

Thank  you.

Regards,

parimala