Re: [PATCH v1 11/15] serial: imx: initialized DMA w/o HW flow enabled

From: jiwang
Date: Fri Apr 17 2015 - 05:18:52 EST


Hello Sebastian

On 04/13/2015 05:06 PM, Sebastian Andrzej Siewior wrote:
On Mon, Apr 13, 2015 at 04:40:15PM +0900, jiwang wrote:
Hi Sebastian
Hi Jiada,

My question is how was this tested. Before your patch none of my boards
were using DMA because RTS/CTS is not in use and this was a key
requirement. Now SDMA goes crazy. Is there a SDMA firmware required for
this to work?
We tested the patch set with our modified kernel tree,
and I find upstream kernel is not building SDMA firmware,
I will submit another patch to add it.
Please make sure it is tagged stable. There is no hint that this is required
and as of it now, it breaks v4.0.
Due to missing of SDMA firmware, uart sdma mode is broken,
but it is uncovered by this commit on your environment.

One question, where do you have the firmware from? I picked the one from FSL's
v3.10 SDK and I ended up with FIFO-overflows so it was clearly the wrong one
(and the built-in SDMA firmware does not work as expected as you mentioned).
I got sdma firmware from FSL kernel tree.
Is this firmware only required the imx6 series or also for older versions like
imx5?
the firmware only supports imx6 series, AFAIK,
I checked with Freescale imx6 support team, due to
licensing issue, I am not entitled to upstream FSL SDMA firmware.
so seems currently disable SDMA support for uart is our only option
at the moment.

Thanks,
Jiada
Thanks,
Jiada
Sebastian

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