Re: [PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts

[Romain Perier]

Hello,


Le 03/07/2017 à 08:48, Uwe Kleine-König a écrit :
> Hello,
>
> On Fri, Jun 30, 2017 at 02:04:40PM +0200, Romain Perier wrote:
>> From: Nandor Han 
>>
>> Avoid the situation when `dma_is_rxing` could incorrectly signal that
>> DMA RX channel is receiving data in case DMA preparation or sg mapping
>> fails.
> Just from reading the commit log and the patch I didn't understand the
> problem that is supposed to be fixed here. After looking at it for some
> I understood. I don't suggest a new commit log here as it has to look
> different if you pick up my comment below.
>
>> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
>> index 5437b34..1d35293 100644
>> --- a/drivers/tty/serial/imx.c
>> +++ b/drivers/tty/serial/imx.c
>> @@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
>>  return IRQ_HANDLED;
>>  }
>>  
>> -static void imx_disable_rx_int(struct imx_port *sport)
>> +static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing)
>>  {
>>  unsigned long temp;
>>  
>> -sport->dma_is_rxing = 1;
>> +sport->dma_is_rxing = is_rxing;
>>  
>>  /* disable the receiver ready and aging timer interrupts */
>>  temp = readl(sport->port.membase + UCR1);
>> @@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport)
>>  temp = readl(sport->port.membase + USR2);
>>  if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
>>  
>> -imx_disable_rx_int(sport);
>> +imx_disable_rx_int(sport, false);
>>  
>>  /* tell the DMA to receive the data. */
>>  start_rx_dma(sport);
>> @@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport)
>>  desc->callback_param = sport;
>>  
>>  dev_dbg(dev, "RX: prepare for the DMA.\n");
>> +sport->dma_is_rxing = 1;
>>  sport->rx_cookie = dmaengine_submit(desc);
>>  dma_async_issue_pending(chan);
>>  return 0;
>> @@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port)
>>  spin_unlock(>files_lock);
>>  
>>  if (readcnt > 0) {
>> -imx_disable_rx_int(sport);
>> +imx_disable_rx_int(sport, true);
> I wonder if it would be saner to not assign to dma_is_rxing in
> imx_disable_rx_int() at all but do this only in start_rx_dma() and
> imx_dma_rxint().

It was "mostly" done, in 4.11 in fact.  dma_is_rxing was set to 0 from
imx_dma_rxint() and was not set
at all from start_rx_dma(), resulting to the same issue. We could move
assignment of dma_is_rxing out of imx_disable_rx_int()
and set it to one from start_rx_dma() only. What do you think ?

Best Regards,
Romain

>
> Best regards
> Uwe
>

Re: [PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts

[Romain Perier]

Hello,


Le 03/07/2017 à 08:48, Uwe Kleine-König a écrit :
> Hello,
>
> On Fri, Jun 30, 2017 at 02:04:40PM +0200, Romain Perier wrote:
>> From: Nandor Han 
>>
>> Avoid the situation when `dma_is_rxing` could incorrectly signal that
>> DMA RX channel is receiving data in case DMA preparation or sg mapping
>> fails.
> Just from reading the commit log and the patch I didn't understand the
> problem that is supposed to be fixed here. After looking at it for some
> I understood. I don't suggest a new commit log here as it has to look
> different if you pick up my comment below.
>
>> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
>> index 5437b34..1d35293 100644
>> --- a/drivers/tty/serial/imx.c
>> +++ b/drivers/tty/serial/imx.c
>> @@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
>>  return IRQ_HANDLED;
>>  }
>>  
>> -static void imx_disable_rx_int(struct imx_port *sport)
>> +static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing)
>>  {
>>  unsigned long temp;
>>  
>> -sport->dma_is_rxing = 1;
>> +sport->dma_is_rxing = is_rxing;
>>  
>>  /* disable the receiver ready and aging timer interrupts */
>>  temp = readl(sport->port.membase + UCR1);
>> @@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport)
>>  temp = readl(sport->port.membase + USR2);
>>  if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
>>  
>> -imx_disable_rx_int(sport);
>> +imx_disable_rx_int(sport, false);
>>  
>>  /* tell the DMA to receive the data. */
>>  start_rx_dma(sport);
>> @@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport)
>>  desc->callback_param = sport;
>>  
>>  dev_dbg(dev, "RX: prepare for the DMA.\n");
>> +sport->dma_is_rxing = 1;
>>  sport->rx_cookie = dmaengine_submit(desc);
>>  dma_async_issue_pending(chan);
>>  return 0;
>> @@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port)
>>  spin_unlock(>files_lock);
>>  
>>  if (readcnt > 0) {
>> -imx_disable_rx_int(sport);
>> +imx_disable_rx_int(sport, true);
> I wonder if it would be saner to not assign to dma_is_rxing in
> imx_disable_rx_int() at all but do this only in start_rx_dma() and
> imx_dma_rxint().

It was "mostly" done, in 4.11 in fact.  dma_is_rxing was set to 0 from
imx_dma_rxint() and was not set
at all from start_rx_dma(), resulting to the same issue. We could move
assignment of dma_is_rxing out of imx_disable_rx_int()
and set it to one from start_rx_dma() only. What do you think ?

Best Regards,
Romain

>
> Best regards
> Uwe
>

Re: [PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts

[Uwe Kleine-König]

Hello,

On Fri, Jun 30, 2017 at 02:04:40PM +0200, Romain Perier wrote:
> From: Nandor Han 
> 
> Avoid the situation when `dma_is_rxing` could incorrectly signal that
> DMA RX channel is receiving data in case DMA preparation or sg mapping
> fails.

Just from reading the commit log and the patch I didn't understand the
problem that is supposed to be fixed here. After looking at it for some
I understood. I don't suggest a new commit log here as it has to look
different if you pick up my comment below.

> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 5437b34..1d35293 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
>   return IRQ_HANDLED;
>  }
>  
> -static void imx_disable_rx_int(struct imx_port *sport)
> +static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing)
>  {
>   unsigned long temp;
>  
> - sport->dma_is_rxing = 1;
> + sport->dma_is_rxing = is_rxing;
>  
>   /* disable the receiver ready and aging timer interrupts */
>   temp = readl(sport->port.membase + UCR1);
> @@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport)
>   temp = readl(sport->port.membase + USR2);
>   if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
>  
> - imx_disable_rx_int(sport);
> + imx_disable_rx_int(sport, false);
>  
>   /* tell the DMA to receive the data. */
>   start_rx_dma(sport);
> @@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport)
>   desc->callback_param = sport;
>  
>   dev_dbg(dev, "RX: prepare for the DMA.\n");
> + sport->dma_is_rxing = 1;
>   sport->rx_cookie = dmaengine_submit(desc);
>   dma_async_issue_pending(chan);
>   return 0;
> @@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port)
>   spin_unlock(>files_lock);
>  
>   if (readcnt > 0) {
> - imx_disable_rx_int(sport);
> + imx_disable_rx_int(sport, true);

I wonder if it would be saner to not assign to dma_is_rxing in
imx_disable_rx_int() at all but do this only in start_rx_dma() and
imx_dma_rxint().

Best regards
Uwe

-- 
Pengutronix e.K.   | Uwe Kleine-König|
Industrial Linux Solutions | http://www.pengutronix.de/  |

Re: [PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts

[Uwe Kleine-König]

Hello,

On Fri, Jun 30, 2017 at 02:04:40PM +0200, Romain Perier wrote:
> From: Nandor Han 
> 
> Avoid the situation when `dma_is_rxing` could incorrectly signal that
> DMA RX channel is receiving data in case DMA preparation or sg mapping
> fails.

Just from reading the commit log and the patch I didn't understand the
problem that is supposed to be fixed here. After looking at it for some
I understood. I don't suggest a new commit log here as it has to look
different if you pick up my comment below.

> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 5437b34..1d35293 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
>   return IRQ_HANDLED;
>  }
>  
> -static void imx_disable_rx_int(struct imx_port *sport)
> +static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing)
>  {
>   unsigned long temp;
>  
> - sport->dma_is_rxing = 1;
> + sport->dma_is_rxing = is_rxing;
>  
>   /* disable the receiver ready and aging timer interrupts */
>   temp = readl(sport->port.membase + UCR1);
> @@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport)
>   temp = readl(sport->port.membase + USR2);
>   if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
>  
> - imx_disable_rx_int(sport);
> + imx_disable_rx_int(sport, false);
>  
>   /* tell the DMA to receive the data. */
>   start_rx_dma(sport);
> @@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport)
>   desc->callback_param = sport;
>  
>   dev_dbg(dev, "RX: prepare for the DMA.\n");
> + sport->dma_is_rxing = 1;
>   sport->rx_cookie = dmaengine_submit(desc);
>   dma_async_issue_pending(chan);
>   return 0;
> @@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port)
>   spin_unlock(>files_lock);
>  
>   if (readcnt > 0) {
> - imx_disable_rx_int(sport);
> + imx_disable_rx_int(sport, true);

I wonder if it would be saner to not assign to dma_is_rxing in
imx_disable_rx_int() at all but do this only in start_rx_dma() and
imx_dma_rxint().

Best regards
Uwe

-- 
Pengutronix e.K.   | Uwe Kleine-König|
Industrial Linux Solutions | http://www.pengutronix.de/  |

[PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts

[Romain Perier]

From: Nandor Han 

Avoid the situation when `dma_is_rxing` could incorrectly signal that
DMA RX channel is receiving data in case DMA preparation or sg mapping
fails.

Signed-off-by: Nandor Han 
Signed-off-by: Romain Perier 
---
 drivers/tty/serial/imx.c | 9 +
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 5437b34..1d35293 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
return IRQ_HANDLED;
 }
 
-static void imx_disable_rx_int(struct imx_port *sport)
+static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing)
 {
unsigned long temp;
 
-   sport->dma_is_rxing = 1;
+   sport->dma_is_rxing = is_rxing;
 
/* disable the receiver ready and aging timer interrupts */
temp = readl(sport->port.membase + UCR1);
@@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport)
temp = readl(sport->port.membase + USR2);
if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
 
-   imx_disable_rx_int(sport);
+   imx_disable_rx_int(sport, false);
 
/* tell the DMA to receive the data. */
start_rx_dma(sport);
@@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport)
desc->callback_param = sport;
 
dev_dbg(dev, "RX: prepare for the DMA.\n");
+   sport->dma_is_rxing = 1;
sport->rx_cookie = dmaengine_submit(desc);
dma_async_issue_pending(chan);
return 0;
@@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port)
spin_unlock(>files_lock);
 
if (readcnt > 0) {
-   imx_disable_rx_int(sport);
+   imx_disable_rx_int(sport, true);
start_rx_dma(sport);
}
}
-- 
1.8.3.1

[PATCH 1/7] serial: imx: only set DMA rx-ing when DMA starts

[Romain Perier]

From: Nandor Han 

Avoid the situation when `dma_is_rxing` could incorrectly signal that
DMA RX channel is receiving data in case DMA preparation or sg mapping
fails.

Signed-off-by: Nandor Han 
Signed-off-by: Romain Perier 
---
 drivers/tty/serial/imx.c | 9 +
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 5437b34..1d35293 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -725,11 +725,11 @@ static irqreturn_t imx_rxint(int irq, void *dev_id)
return IRQ_HANDLED;
 }
 
-static void imx_disable_rx_int(struct imx_port *sport)
+static void imx_disable_rx_int(struct imx_port *sport, bool is_rxing)
 {
unsigned long temp;
 
-   sport->dma_is_rxing = 1;
+   sport->dma_is_rxing = is_rxing;
 
/* disable the receiver ready and aging timer interrupts */
temp = readl(sport->port.membase + UCR1);
@@ -762,7 +762,7 @@ static void imx_dma_rxint(struct imx_port *sport)
temp = readl(sport->port.membase + USR2);
if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
 
-   imx_disable_rx_int(sport);
+   imx_disable_rx_int(sport, false);
 
/* tell the DMA to receive the data. */
start_rx_dma(sport);
@@ -1083,6 +1083,7 @@ static int start_rx_dma(struct imx_port *sport)
desc->callback_param = sport;
 
dev_dbg(dev, "RX: prepare for the DMA.\n");
+   sport->dma_is_rxing = 1;
sport->rx_cookie = dmaengine_submit(desc);
dma_async_issue_pending(chan);
return 0;
@@ -1362,7 +1363,7 @@ static int imx_startup(struct uart_port *port)
spin_unlock(>files_lock);
 
if (readcnt > 0) {
-   imx_disable_rx_int(sport);
+   imx_disable_rx_int(sport, true);
start_rx_dma(sport);
}
}
-- 
1.8.3.1