linux-kernel - Re: [PATCH v1 12/12] serial: 8250_lpss: enable DMA on Intel Quark UART

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Message-ID: <CAHp75VdFoPWKyxHtcdDC=O+xQ2L7rXWFqBJg5LGe+tnnzA56Uw@mail.gmail.com>
Date:	Mon, 11 Apr 2016 19:05:04 +0300
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	"Bryan O'Donoghue" <pure.logic@...us-software.ie>,
	Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Vinod Koul <vinod.koul@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	dmaengine <dmaengine@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Puustinen, Ismo" <ismo.puustinen@...el.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
Subject: Re: [PATCH v1 12/12] serial: 8250_lpss: enable DMA on Intel Quark UART

On Mon, Apr 11, 2016 at 6:51 PM, Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
> On Mon, Apr 11, 2016 at 6:33 PM, Bryan O'Donoghue
> <pure.logic@...us-software.ie> wrote:
>> On Thu, 2016-04-07 at 23:37 +0300, Andy Shevchenko wrote:
>>
>> Preface. I tried this on Galileo and it appears to work. I'll do some
>> throughput testing to verify but, initially the results are positive :)
>
> I submitted (and pushed into my branch) a bit changed version (see my v2).
>
>>> +       lpss->dma_maxburst = 8;
>>
>> Are these dwords ? If those are bytes then the maxburst value looks
>> small. In the BSP the max burst is 32 bytes.
>
> max_burst is in items of given size (here is 32 bytes for memory and 8
> bytes for UART). I took this value from Quark BSP, but I'll be happy
> to adjust to more optimal values.

+Jarkko.

Oy vei, seems we don't set memory side of transfer neither in
8250_dma, nor in spi-pxa2xx-dma.

-- 
With Best Regards,
Andy Shevchenko