I'm setting up a board using the am335x processor family that needs to communicate over UART0 with hardware flow control using the legacy omap_serial driver (can't use the 8250 driver because I need RS485 support as well). Currently I'm getting a kernel fault when communicating so have been searching around the net for solutions.
The wiki page for the WL18xx chipset states that if HW flow control should be used a certain patch should be applied and links to a path on TI's servers. However, the link is not working. Does anyone have the patch on their disks and can provide it to me? Or is the NULL pointer exception a known problem?
Thanks,
// Måns
http://processors.wiki.ti.com/index.php/WL18xx_Platform_Integration_Guide#UART_Initialization
Patch link
https://gforge.ti.com/gf/download/frsrelease/1281/7776/0001-OMAP-SERIAL-Enable-HW-flow-control.patch
Stack trace (upstream v4.4)
[ 69.079358] Unable to handle kernel NULL pointer dereference at virtual address 00000124
[ 69.087892] pgd = c0004000
[ 69.090738] [00000124] *pgd=00000000
[ 69.094509] Internal error: Oops: 17 [#1] ARM
[ 69.099099] CPU: 0 PID: 6 Comm: kworker/u2:0 Not tainted 4.4.0 #19
[ 69.105594] Hardware name: Generic AM33XX (Flattened Device Tree)
[ 69.112021] Workqueue: events_unbound flush_to_ldisc
[ 69.117243] task: cf038080 ti: cf058000 task.ti: cf058000
[ 69.122923] PC is at __uart_start+0x1c/0x44
[ 69.127321] LR is at uart_start+0x18/0x20
[ 69.131538] pc : [<c02826e0>] lr : [<c0282720>] psr: a0000093
[ 69.131538] sp : cf059e08 ip : cf059e18 fp : cf059e14
[ 69.143604] r10: ffffffff r9 : 0000000d r8 : cdbbe423
[ 69.149096] r7 : d0c55000 r6 : d0c55000 r5 : d0c57268 r4 : a0000013
[ 69.155956] r3 : 00000000 r2 : 00000001 r1 : 00000000 r0 : cf1da810
[ 69.162820] Flags: NzCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment none
[ 69.170411] Control: 10c5387d Table: 8f658019 DAC: 00000051
[ 69.176450] Process kworker/u2:0 (pid: 6, stack limit = 0xcf058210)
