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

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Date:	Sun, 20 Dec 2015 17:11:51 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Julian Margetson <runaway@...dw.ms>
Cc:	Andy Shevchenko <andy.shevchenko@...il.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Tejun Heo <tj@...nel.org>, linux-ide@...r.kernel.org,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find dma channel

Julian Margetson <runaway@...dw.ms> writes:

> On 12/19/2015 4:41 PM, Måns Rullgård wrote:
>> Andy Shevchenko <andy.shevchenko@...il.com> writes:
>>
>>> On Sat, Dec 19, 2015 at 10:16 PM, Julian Margetson <runaway@...dw.ms> wrote:
>>>> On 12/19/2015 3:07 PM, Måns Rullgård wrote:
>>>>> Julian Margetson <runaway@...dw.ms> writes:
>>>>>> Total pages: 522752
>>>>>> [    0.000000] Kernel command line: root=/dev/sda8 console=ttyS0,115200
>>>>>> console=tty1 dw_dmac_core.dyndbg dw_dmac.dyndbg
>>>>> Please add ignore_log_level.
>>>>>
>>>> Had to truncate the kernel command line to add it.
>>> I guess Måns meant 'ignore_loglevel'
>> Obviously.  I can never remember where the underscores go.
>
> [   18.362244] sd 3:0:0:0: [sdc] 976773168 512-byte logical blocks: (500 GB/465 GiB)
> [   18.372454] sd 3:0:0:0: Attached scsi generic sg3 type 0
> [   18.405433] sd 3:0:0:0: [sdc] Write Protect is off
> [   18.420654] sd 3:0:0:0: [sdc] Mode Sense: 00 3a 00 00
> [   18.461731] sd 3:0:0:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> [   18.502918] sata-dwc 4bffd1000.sata: sata_dwc_qc_prep_by_tag: port=0 dma dir=from device n_elem=1
> [   18.511807] dma dma0chan0: dwc_prep_slave_sg
> [   18.516083] dma dma0chan0: scanned 1 descriptors on freelist
> [   18.521753] sata-dwc 4bffd1000.sata: dma_dwc_xfer_setup sg: 0xedeaa800, count: 1 addr: 0xfffffffff6a14400
> [   18.531327] sata-dwc 4bffd1000.sata: sata_dwc_qc_issue: tag=0 ap->link.sactive = 0x00000001 sactive=0x00000001
> [   18.541359] sata-dwc 4bffd1000.sata: sata_dwc_exec_command_by_tag cmd(0x60): READ FPDMA QUEUED tag=0
> [   18.553703] sata-dwc 4bffd1000.sata: sata_dwc_isr intpr=0x00000082 active_tag=-84148995
> [   18.561717] sata-dwc 4bffd1000.sata: sata_dwc_isr: NEWFP tag=0
> [   18.567561] sata-dwc 4bffd1000.sata: sata_dwc_bmdma_start_by_tag qc=ed2340b8 tag: 0 cmd: 0x60 dma_dir: from device start_dma? 1
> [   18.579043] sata-dwc 4bffd1000.sata: taskfile cmd: 0x60 protocol: ATA NCQ flags: 0x17 device: 40
> [   18.587836] sata-dwc 4bffd1000.sata: feature: 0x08 nsect: 0x0 lbal: 0x0 lbam: 0x0 lbah: 0x0
> [   18.596196] sata-dwc 4bffd1000.sata: hob_feature: 0x00 hob_nsect: 0x0 hob_lbal: 0x0 hob_lbam: 0x0 hob_lbah: 0x0
> [   18.606292] dma dma0chan0: dwc_tx_submit: queued 2
> [   18.611091] dma dma0chan0: dwc_dostart_first_queued: started 2
> [   48.748614] ata3: lost interrupt (Status 0x40)

Now we're getting somewhere.  The dma transfer is set up and initiated,
but then nothing happens.  Comparing the old sata_dwc driver, from
before the switch to dmaengine, with the dw_dma driver, I noticed an
obvious problem: the descriptors are filled in using the wrong byte
order.  This patch might fix that.

-- 
Måns Rullgård

View attachment "0001-dmaengine-dw-fix-byte-order-of-hw-descriptor-fields.patch" of type "text/x-diff" (8764 bytes)