Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

["Måns Rullgård" <mans@mansr.com>]

Julian Margetson <runaway@candw.ms> writes:

> On 12/18/2015 8:49 AM, Måns Rullgård wrote:
>> Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
>>
>>>>> [    5.206125] Unable to handle kernel paging request for data at
>>>>> address 0x00000000
>>>>> [    5.228546] Faulting instruction address: 0xc043a2c8
>>>>> [    5.248577] Vector: 300 (Data Access) at [eddafae0]
>>>>> [    5.268658]     pc: c043a2c8: sata_dwc_qc_issue+0xb8/0x204
>>>> Well, that's not good.  Can you translate that address to a line of
>>>> code?
>>> Besides that, can you enable DYNAMIC_DEBUG in the config and append
>>> 'dw_dmac_core.dyndbg dw_dmac.dyndbg' to the kernel cmdline?
>> Enabling debug messages in the sata_dwc driver might also be informative.
>>
> Changed the sata-dwc to a module .
>
> [   18.475140] sata-dwc 4bffd1000.sata: sata_dwc_qc_prep_by_tag: dma_dwc_xfer_setup returns NULL
> [   18.535698] sata-dwc 4bffd1000.sata: sata_dwc_qc_prep_by_tag: dma_dwc_xfer_setup returns NULL

That's strange.  The only way that can happen is if
dmaengine_prep_slave_sg() return NULL, and that really shouldn't be
happening.  Did you turn on debug messages in dw_dma?  You can enable
some extra debug messages by adding "#define VERBOSE_DEBUG" at the top
of drivers/dma/dw/core.c

-- 
Måns Rullgård