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 22:55:01 +0200
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Måns Rullgård <mans@...sr.com>
Cc:	Julian Margetson <runaway@...dw.ms>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Tejun Heo <tj@...nel.org>, linux-ide@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] ata: sata_dwc_460ex: use "dmas" DT property to find
 dma channel

On Sun, Dec 20, 2015 at 10:17 PM, Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
> On Sun, Dec 20, 2015 at 8:49 PM, Måns Rullgård <mans@...sr.com> wrote:
>> Julian Margetson <runaway@...dw.ms> writes:
>>> On 12/20/2015 1:11 PM, Måns Rullgård wrote:
>>>> Julian Margetson <runaway@...dw.ms> writes:
>
>>> [   48.769671] ata3.00: failed command: READ FPDMA QUEUED
>>
>> Well, that didn't help.  I still think it's part of the problem, but
>> something else must be wrong as well.  The various Master Select fields
>> look like a good place to start.
>
> Master number (which is here would be either 1 or 0) should not affect
> as long as they are connected to the same AHB bus (I would be
> surprised if they are not).
>
>>  Also, the manual says the LLP_SRC_EN
>> and LLP_DST_EN flags should be cleared on the last in a chain of blocks.
>> The old sata_dwc driver does this whereas dw_dma does not.
>
> Easy to fix, however I can't get how it might affect.
>
>> It might be worthwhile to try reverting drivers/ata/sata_dwc_460ex.c to
>> v4.0 (leaving the rest at 4.4-rc5) just to make sure that's a good
>> reference.  I've verified that this builds.
>
> It would be nice.
>
> I noticed thanks to DWC_PARAMS that burst size is hardcoded to 32
> items on this board, however registers for SATA program it to 64. I
> remember that I got no interrupt when I programmed transfer width
> wrongly (64 bits against 32 bits) when I ported dw_dmac to be used on
> Intel SoCs.

One more thing, I have a patch to monitor DMA IO, we may check what
exactly the values are written / read  in DMA. I can share it
tomorrow.

P.S. I also noticed that original driver enables interrupt per each
block and sets protection control bits.

-- 
With Best Regards,
Andy Shevchenko
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