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Subject: Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find
 dma channel
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: =?ISO-8859-1?Q?M=E5ns_Rullg=E5rd?= <mans@mansr.com>,
        Julian Margetson <runaway@candw.ms>
Cc: Tejun Heo <tj@kernel.org>, linux-ide@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date: Fri, 18 Dec 2015 20:48:29 +0200
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On Fri, 2015-12-18 at 17:18 +0000, Måns Rullgård wrote:
> 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

There are options also for DMA Engine such as CONFIG_DMADEVICES_DEBUG

> 

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy