fbdev: omap: use threaded IRQ for LCD DMA

In the Linux kernel, the following vulnerability has been resolved:

fbdev: omap: use threaded IRQ for LCD DMA

When using touchscreen and framebuffer, Nokia 770 crashes easily with:

BUG: scheduling while atomic: irq/144-ads7846/82/0x00010000

Modules linked in: usb_f_ecm g_ether usb_f_rndis u_ether libcomposite configfs omap_udc ohci_omap ohci_hcd

CPU: 0 UID: 0 PID: 82 Comm: irq/144-ads7846 Not tainted 6.12.7-770 #2

Hardware name: Nokia 770

Call trace:

unwind_backtrace from show_stack+0x10/0x14

show_stack from dump_stack_lvl+0x54/0x5c

dump_stack_lvl from __schedule_bug+0x50/0x70

__schedule_bug from __schedule+0x4d4/0x5bc

__schedule from schedule+0x34/0xa0

schedule from schedule_preempt_disabled+0xc/0x10

schedule_preempt_disabled from __mutex_lock.constprop.0+0x218/0x3b4

__mutex_lock.constprop.0 from clk_prepare_lock+0x38/0xe4

clk_prepare_lock from clk_set_rate+0x18/0x154

clk_set_rate from sossi_read_data+0x4c/0x168

sossi_read_data from hwa742_read_reg+0x5c/0x8c

hwa742_read_reg from send_frame_handler+0xfc/0x300

send_frame_handler from process_pending_requests+0x74/0xd0

process_pending_requests from lcd_dma_irq_handler+0x50/0x74

lcd_dma_irq_handler from __handle_irq_event_percpu+0x44/0x130

__handle_irq_event_percpu from handle_irq_event+0x28/0x68

handle_irq_event from handle_level_irq+0x9c/0x170

handle_level_irq from generic_handle_domain_irq+0x2c/0x3c

generic_handle_domain_irq from omap1_handle_irq+0x40/0x8c

omap1_handle_irq from generic_handle_arch_irq+0x28/0x3c

generic_handle_arch_irq from call_with_stack+0x1c/0x24

call_with_stack from __irq_svc+0x94/0xa8

Exception stack(0xc5255da0 to 0xc5255de8)

5da0: 00000001 c22fc620 00000000 00000000 c08384a8 c106fc00 00000000 c240c248

5dc0: c113a600 c3f6ec30 00000001 00000000 c22fc620 c5255df0 c22fc620 c0279a94

5de0: 60000013 ffffffff

__irq_svc from clk_prepare_lock+0x4c/0xe4

clk_prepare_lock from clk_get_rate+0x10/0x74

clk_get_rate from uwire_setup_transfer+0x40/0x180

uwire_setup_transfer from spi_bitbang_transfer_one+0x2c/0x9c

spi_bitbang_transfer_one from spi_transfer_one_message+0x2d0/0x664

spi_transfer_one_message from __spi_pump_transfer_message+0x29c/0x498

__spi_pump_transfer_message from __spi_sync+0x1f8/0x2e8

__spi_sync from spi_sync+0x24/0x40

spi_sync from ads7846_halfd_read_state+0x5c/0x1c0

ads7846_halfd_read_state from ads7846_irq+0x58/0x348

ads7846_irq from irq_thread_fn+0x1c/0x78

irq_thread_fn from irq_thread+0x120/0x228

irq_thread from kthread+0xc8/0xe8

kthread from ret_from_fork+0x14/0x28

As a quick fix, switch to a threaded IRQ which provides a stable system.