[BUG] atmel: spi: scheduling while atomic

[Alexandre Belloni]

Hi,

On 05/03/2014 at 07:56:04 +0100, Jiří Prchal wrote :
> Hi Alex,
> I have a bad news, disabling dma does not help.
> 
> [    0.000000] Booting Linux on physical CPU 0x0
> [    0.000000] Linux version 3.14.0-rc4_cpm9g25+ (prchal at prchal)
> (gcc version 4.5.2 (GCC) ) #1 PREEMPT Tue Mar 4 14:28:23 CET 2014
> [    0.000000] CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177
> ...
> [    0.878906] atmel_spi f0000000.spi: version: 0x212
> [    0.882812] of_dma_request_slave_channel: dma-names property of node '/ahb/apb/spi at f0000000' missing or empty
> [    0.886718] atmel_spi f0000000.spi: DMA TX channel not available, SPI unable to use DMA
> [    0.890625] atmel_spi f0000000.spi: Atmel SPI Controller using PIO only
> [    0.894531] atmel_spi f0000000.spi: Atmel SPI Controller at 0xf0000000 (irq 28)
> ...
> [    0.902343] BUG: scheduling while atomic: spi0/383/0x00000002
> [    0.906250] Modules linked in:
> [    0.906250] CPU: 0 PID: 383 Comm: spi0 Not tainted 3.14.0-rc4_cpm9g25+ #1
> [    0.906250] [<c000d9f4>] (unwind_backtrace) from [<c000bdc0>] (show_stack+0x10/0x14)
> [    0.906250] [<c000bdc0>] (show_stack) from [<c003a224>] (__schedule_bug+0x48/0x60)
> [    0.906250] [<c003a224>] (__schedule_bug) from [<c0390294>] (__schedule+0x60/0x484)
> [    0.906250] [<c0390294>] (__schedule) from [<c038feac>] (schedule_timeout+0x17c/0x1ac)
> [    0.906250] [<c038feac>] (schedule_timeout) from [<c039111c>] (wait_for_common+0x10c/0x1f0)
> [    0.906250] [<c039111c>] (wait_for_common) from [<c0249228>] (atmel_spi_transfer_one_message+0x71c/0xa48)
> [    0.906250] [<c0249228>] (atmel_spi_transfer_one_message) from [<c0246624>] (spi_pump_messages+0x210/0x238)
> [    0.906250] [<c0246624>] (spi_pump_messages) from [<c00343d0>] (kthread_worker_fn+0x15c/0x1b4)
> [    0.906250] [<c00343d0>] (kthread_worker_fn) from [<c0034534>] (kthread+0xb8/0xcc)
> [    0.906250] [<c0034534>] (kthread) from [<c0009510>] (ret_from_fork+0x14/0x24)
> [    0.906250] at25 spi0.0: 128 KByte at25 eeprom, pagesize 512
> ...
> [   62.527343] BUG: scheduling while atomic: spi0/383/0x00000002
> [   62.531250] Modules linked in:
> [   62.531250] CPU: 0 PID: 383 Comm: spi0 Tainted: G        W    3.14.0-rc4_cpm9g25+ #1
> [   62.531250] [<c000d9f4>] (unwind_backtrace) from [<c000bdc0>] (show_stack+0x10/0x14)
> [   62.531250] [<c000bdc0>] (show_stack) from [<c003a224>] (__schedule_bug+0x48/0x60)
> [   62.531250] [<c003a224>] (__schedule_bug) from [<c0390294>] (__schedule+0x60/0x484)
> [   62.531250] [<c0390294>] (__schedule) from [<c038feac>] (schedule_timeout+0x17c/0x1ac)
> [   62.531250] [<c038feac>] (schedule_timeout) from [<c039111c>] (wait_for_common+0x10c/0x1f0)
> [   62.531250] [<c039111c>] (wait_for_common) from [<c0249228>] (atmel_spi_transfer_one_message+0x71c/0xa48)
> [   62.531250] [<c0249228>] (atmel_spi_transfer_one_message) from [<c0246624>] (spi_pump_messages+0x210/0x238)
> [   62.531250] [<c0246624>] (spi_pump_messages) from [<c00343d0>] (kthread_worker_fn+0x15c/0x1b4)
> [   62.531250] [<c00343d0>] (kthread_worker_fn) from [<c0034534>] (kthread+0xb8/0xcc)
> [   62.531250] [<c0034534>] (kthread) from [<c0009510>] (ret_from_fork+0x14/0x24)
> 
> 

So I tried, both with an at91sam9rl-ek and an at91sam9m10-g45-ek and I
don't observe that warning. Those boards have an AT45 dataflash do you
see that with other spi devices if you have any ?

Actually, I'm not quite sure how spi_pump_messages can be called from an
atomic context.

Could you share your .config (maybe on pastebin) ?

> Dne 4.3.2014 22:40, Alexandre Belloni napsal(a):
> >Hi Jiří,
> >
> >Thank you for that report.
> >
> >On 04/03/2014 at 15:29:16 +0100, Jiří Prchal wrote :
> >>Hi,
> >>I discovered some problem when I access anything on SPI. But it
> >>seems to work correctly, only log is full of this messages. I've
> >>tried kernels 3.13.0 and 3.14.0, both are the same.
> >>
> >>[    0.875000] atmel_spi f0000000.spi: version: 0x212
> >>[    0.878906] atmel_spi f0000000.spi: Using dma0chan0 (tx) and dma0chan1 (rx) for DMA transfers
> >>[    0.882812] atmel_spi f0000000.spi: Atmel SPI Controller at 0xf0000000 (irq 28)
> >>...
> >
> >For now, as a work around, I would suggest disabling dma. I believe it
> >will solve that particular issue but I didn't try. I would be grateful
> >if you could post the result.
> >

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com