[PATCH v3 1/1] tty: serial: imx: allow breaks to be received when using dma

[Troy Kisky]

On 2/20/2018 11:59 AM, Uwe Kleine-König wrote:
> On Tue, Feb 20, 2018 at 10:20:37AM -0800, Troy Kisky wrote:
>> This allows me to login after sending a break when service
>> serial-getty at ttymxc0.service is running
>>
>> The "tty_insert_flip_char(port, 0, TTY_BREAK)" in clear_rx_errors
>> fixes this by allowing the higher layers to see a break.
>>
>> Signed-off-by: Troy Kisky <troy.kisky at boundarydevices.com>
>> Tested-by: Martin Hicks <mort at bork.org>
>>
>> ---
>> v2: rebase only
>> v3: change commit message as requested by Fabio,
>>     add tested-by
>> ---
>>  drivers/tty/serial/imx.c | 20 +++++++++++++-------
>>  1 file changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
>> index 1d7ca382bc12..2eb8c4a20d68 100644
>> --- a/drivers/tty/serial/imx.c
>> +++ b/drivers/tty/serial/imx.c
>> @@ -927,7 +927,6 @@ static void dma_rx_callback(void *data)
>>  	status = dmaengine_tx_status(chan, (dma_cookie_t)0, &state);
>>  
>>  	if (status == DMA_ERROR) {
>> -		dev_err(sport->port.dev, "DMA transaction error.\n");
>>  		clear_rx_errors(sport);
>>  		return;
>>  	}
>> @@ -1028,6 +1027,7 @@ static int start_rx_dma(struct imx_port *sport)
>>  
>>  static void clear_rx_errors(struct imx_port *sport)
>>  {
>> +	struct tty_port *port = &sport->port.state->port;
>>  	unsigned int status_usr1, status_usr2;
>>  
>>  	status_usr1 = readl(sport->port.membase + USR1);
>> @@ -1036,12 +1036,18 @@ static void clear_rx_errors(struct imx_port *sport)
>>  	if (status_usr2 & USR2_BRCD) {
>>  		sport->port.icount.brk++;
>>  		writel(USR2_BRCD, sport->port.membase + USR2);
>> -	} else if (status_usr1 & USR1_FRAMERR) {
>> -		sport->port.icount.frame++;
>> -		writel(USR1_FRAMERR, sport->port.membase + USR1);
>> -	} else if (status_usr1 & USR1_PARITYERR) {
>> -		sport->port.icount.parity++;
>> -		writel(USR1_PARITYERR, sport->port.membase + USR1);
>> +		if (tty_insert_flip_char(port, 0, TTY_BREAK) == 0)
>> +			sport->port.icount.buf_overrun++;
>> +		tty_flip_buffer_push(port);
> 
> I think this needs to call uart_handle_break() as imx_rxint() does. Not sure
> how to properly handle SYSRQ in the dma case though.
> 


SYSRQ is only for the console port, and console port is never dma. But UPF_SAK may be
an issue. I don't know enough about "Secure Attention Key" to say.


Should I add uart_handle_break anyway ?

>> +	} else {
>> +		dev_err(sport->port.dev, "DMA transaction error.\n");
>> +		if (status_usr1 & USR1_FRAMERR) {
>> +			sport->port.icount.frame++;
>> +			writel(USR1_FRAMERR, sport->port.membase + USR1);
>> +		} else if (status_usr1 & USR1_PARITYERR) {
>> +			sport->port.icount.parity++;
>> +			writel(USR1_PARITYERR, sport->port.membase + USR1);
>> +		}
>>  	}
>>  
>>  	if (status_usr2 & USR2_ORE) {
>> -- 
>> 2.14.1
>>
>>
>