linux-kernel - Re: [PATCH 1/8] tty: serial: fsl_lpuart: consider TX FIFO too in tx

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Date:	Tue, 28 Jun 2016 09:24:00 +0530
From:	Bhuvanchandra DV <bhuvanchandra.dv@...adex.com>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	<stefan@...er.ch>, <shawnguo@...nel.org>, <kernel@...gutronix.de>,
	<mturquette@...libre.com>, <sboyd@...eaurora.org>,
	<jslaby@...e.com>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-serial@...r.kernel.org>
Subject: Re: [PATCH 1/8] tty: serial: fsl_lpuart: consider TX FIFO too in
 tx_empty

On 06/26/16 02:56, Greg KH wrote:

> On Thu, Jun 09, 2016 at 08:40:32PM +0530, Bhuvanchandra DV wrote:
>> From: Stefan Agner <stefan@...er.ch>
>>
>> Currently the tx_empty callback only considers the Transmit Complete
>> Flag (TC). The reference manual is not quite clear if the TC flag
>> covers the TX FIFO too. Debug prints on real hardware have shown that
>> from time to time the TC flag is asserted (indicating Transmitter
>> idle) while there are still data in the TX FIFO. Hence, in this case
>> the serial core will call the shutdown callback even though there are
>> data remaining in the TX FIFO buffers.
>>
>> Avoid early shutdowns by considering the TX FIFO empty flag too. Also
>> avoid theoretical race conditions between DMA and the driver by
>> checking whether the TX DMA is in progress too.
>>
>> Signed-off-by: Stefan Agner <stefan@...er.ch>
>> ---
>>   drivers/tty/serial/fsl_lpuart.c | 14 ++++++++++++--
>>   1 file changed, 12 insertions(+), 2 deletions(-)
> Why are you not signing off on patches that are flowing through you?
> Please fix this up and resend the series, after breaking up the clock
> change as asked.

Okay

>
> thanks,
>
> greg k-h