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From: Peter Hurley <peter@hurleysoftware.com>
To: Dirk Behme <dirk.behme@gmail.com>,
	linux-serial@vger.kernel.org, Huang Shijie <b32955@freescale.com>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Wang, Jiada" <Jiada_Wang@mentor.com>,
	Dirk Behme <dirk.behme@de.bosch.com>
Subject: Re: Mainline commit "serial: Test for no tx data on tx restart" not correct for i.MX6?
Date: Wed, 23 Jul 2014 12:32:14 -0400	[thread overview]
Message-ID: <53CFE38E.6070302@hurleysoftware.com> (raw)
In-Reply-To: <53CF3599.6040509@gmail.com>

Hi Dirk,

On 07/23/2014 12:10 AM, Dirk Behme wrote:
> Hi,
> 
> this is a question regarding the i.MX6 part (drivers/tty/serial/imx.c) of the commit
> 
> serial: Test for no tx data on tx restart
> 
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c557d392fbf5badd693ea1946a4317c87a26a716
> 
> Talking with some i.MX6 experts about this, I've got the comment
> 
> -- cut --
> The imx serial driver part of this commit isn't correct
> as imx.c sends x_char in irq handler, not in imx_start_tx(),
> -- cut --
> 
> What do you think?

Thanks for the comment.

Yeah, I missed that the imx driver handled x_char _at all_,
because how the imx driver is handling x_char looks broken.

For example, if data is already in the tx ring buffer,
imx_start_tx() will send that data before the x_char, and if
all the tx ring buffer data is sent successfully, the tx
interrupt is switched back off, so the x_char won't be sent.

Also, the imx driver doesn't send x_char in dma mode?

Regards,
Peter Hurley


  reply	other threads:[~2014-07-23 16:32 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-23  4:10 Mainline commit "serial: Test for no tx data on tx restart" not correct for i.MX6? Dirk Behme
2014-07-23 16:32 ` Peter Hurley [this message]
2014-07-24  8:12   ` jiwang
2014-07-24 11:58     ` Peter Hurley
2014-07-29  7:18       ` jiwang
2014-08-06 23:53         ` Peter Hurley

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