From: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
To: Jiada Wang <jiada_wang@mentor.com>
Cc: gregkh@linuxfoundation.org, jslaby@suse.cz,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
anton_bondarenko@mentor.com, dirk.behme@de.bosch.com
Subject: Re: [PATCH v1 11/15] serial: imx: initialized DMA w/o HW flow enabled
Date: Thu, 9 Apr 2015 14:00:57 +0200 [thread overview]
Message-ID: <20150409120057.GA12596@breakpoint.cc> (raw)
In-Reply-To: <1418116296-12082-12-git-send-email-jiada_wang@mentor.com>
On 2014-12-09 18:11:32 [+0900], Jiada Wang wrote:
> From: Anton Bondarenko <anton_bondarenko@mentor.com>
>
> DMA mode for UART can be used even w/o HW flow control with RTS/CTS.
> So it need to be initialized and enabled earlier.
>
> Signed-off-by: Anton Bondarenko <anton_bondarenko@mentor.com>
> Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
How was this tested? I read you used the Sambe IMX6Q. I have here the
Wandboard which is IMX6D and a PBAB01 which is IMX6Q. Both have the same
issue with this patch, that is once DMA is enabled I receive the data in
question plus one extra byte which is 0x00.
That extra byte was not part of transaction. After that, the SDMA driver
is handling interrupts like crazing and feeding one byte data (usually
0x00 but sometimes 0x02 not sure if this new or whatever was there
before) to the core. Those one byte transaction are bogus of course.
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?
Sebastian
next prev parent reply other threads:[~2015-04-09 12:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-09 9:11 [PATCH v1 00/15] serial: imx: misc fix and features Jiada Wang
2014-12-09 9:11 ` [PATCH v1 01/15] serial: imx: add CREAD flag support Jiada Wang
2014-12-09 9:11 ` [PATCH v1 02/15] serial: imx: use locking to stop concurrent access of UCR1 Jiada Wang
2014-12-09 9:11 ` [PATCH v1 03/15] serial: imx: remove unneeded imx_transmit_buffer() from imx_start_tx() Jiada Wang
2014-12-09 9:11 ` [PATCH v1 04/15] serial: imx: TX DMA: clean up sg initialization Jiada Wang
2014-12-09 9:11 ` [PATCH v1 05/15] serial: imx: unmap sg in case of dmaengine_prep_slave_sg() failure Jiada Wang
2014-12-09 9:11 ` [PATCH v1 06/15] serial: imx: unmap scatter gather list in imx_flush_buffer Jiada Wang
2014-12-09 9:11 ` [PATCH v1 07/15] serial: imx: use dma_is_txing to synchronize dma_tx_callback and imx_dma_tx Jiada Wang
2014-12-09 9:11 ` [PATCH v1 08/15] Revert "serial: imx: always wake up the processes in the TX callback" Jiada Wang
2014-12-09 9:11 ` [PATCH v1 09/15] serial: imx: call imx_dma_tx() again in dma_tx_callback Jiada Wang
2014-12-09 9:11 ` [PATCH v1 10/15] serial: imx: disable TDMAEN in imx_flush_buffer() Jiada Wang
2014-12-09 9:11 ` [PATCH v1 11/15] serial: imx: initialized DMA w/o HW flow enabled Jiada Wang
2015-04-09 12:00 ` Sebastian Andrzej Siewior [this message]
2015-04-13 7:40 ` jiwang
2015-04-13 8:06 ` Sebastian Andrzej Siewior
2015-04-17 9:18 ` jiwang
2015-04-17 10:31 ` Sebastian Andrzej Siewior
2015-05-06 16:08 ` Nicolae Rosia
2015-05-06 16:12 ` Sebastian Andrzej Siewior
2015-05-06 16:46 ` Nicolae Rosia
2015-05-06 17:30 ` Sebastian Andrzej Siewior
2015-05-07 13:55 ` Nicolae Rosia
2015-05-07 13:58 ` Sebastian Andrzej Siewior
2014-12-09 9:11 ` [PATCH v1 12/15] serial: imx: start rx_dma once RXFIFO is not empty Jiada Wang
2014-12-09 9:11 ` [PATCH v1 13/15] serial: imx: Enable UCR4_OREN in startup interface Jiada Wang
2014-12-09 9:11 ` [PATCH v1 14/15] serial: imx: Fix issue in software flow control Jiada Wang
2014-12-09 9:11 ` [PATCH v1 15/15] serial: imx: Support sw flow control in DMA mode Jiada Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150409120057.GA12596@breakpoint.cc \
--to=sebastian@breakpoint.cc \
--cc=anton_bondarenko@mentor.com \
--cc=dirk.behme@de.bosch.com \
--cc=gregkh@linuxfoundation.org \
--cc=jiada_wang@mentor.com \
--cc=jslaby@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).