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* [PATCH] serial: tegra: read DMA status before terminating
@ 2022-10-18  6:25 Kartik
  2022-10-18  6:25 ` Kartik
  2022-10-18 13:18 ` Jon Hunter
  0 siblings, 2 replies; 8+ messages in thread
From: Kartik @ 2022-10-18  6:25 UTC (permalink / raw)
  To: ldewangan, gregkh, jirislaby, thierry.reding, jonathanh, swarren,
	akhilrajeev, linux-serial, linux-tegra, linux-kernel

To get the valid data, read DMA status before terminating the DMA. As
dmaengine_terminate_all() deletes the DMA desc.

Fixes: e9ea096dd225 ("serial: tegra: add serial driver")

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Signed-off-by: Kartik <kkartik@nvidia.com>
---
 drivers/tty/serial/serial-tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index b7170cb9a544..2779b4491f02 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -619,8 +619,8 @@ static void tegra_uart_stop_tx(struct uart_port *u)
 	if (tup->tx_in_progress != TEGRA_UART_TX_DMA)
 		return;
 
-	dmaengine_terminate_all(tup->tx_dma_chan);
 	dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
+	dmaengine_terminate_all(tup->tx_dma_chan);
 	count = tup->tx_bytes_requested - state.residue;
 	async_tx_ack(tup->tx_dma_desc);
 	uart_xmit_advance(&tup->uport, count);
@@ -763,8 +763,8 @@ static void tegra_uart_terminate_rx_dma(struct tegra_uart_port *tup)
 		return;
 	}
 
-	dmaengine_terminate_all(tup->rx_dma_chan);
 	dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
+	dmaengine_terminate_all(tup->rx_dma_chan);
 
 	tegra_uart_rx_buffer_push(tup, state.residue);
 	tup->rx_dma_active = false;
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 8+ messages in thread
* [PATCH] serial: tegra: read DMA status before terminating
  2022-10-18  6:25 [PATCH] serial: tegra: read DMA status before terminating Kartik
@ 2022-10-18  6:25 ` Kartik
  2022-10-18  6:38   ` Greg KH
  2022-10-18 13:18 ` Jon Hunter
  1 sibling, 1 reply; 8+ messages in thread
From: Kartik @ 2022-10-18  6:25 UTC (permalink / raw)
  To: ldewangan, gregkh, jirislaby, thierry.reding, jonathanh, swarren,
	akhilrajeev, linux-serial, linux-tegra, linux-kernel

To get the valid data, read DMA status before terminating the DMA. As
dmaengine_terminate_all() deletes the DMA desc.

Fixes: e9ea096dd225 ("serial: tegra: add serial driver")

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
Signed-off-by: Kartik <kkartik@nvidia.com>
---
 drivers/tty/serial/serial-tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index b7170cb9a544..2779b4491f02 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -619,8 +619,8 @@ static void tegra_uart_stop_tx(struct uart_port *u)
 	if (tup->tx_in_progress != TEGRA_UART_TX_DMA)
 		return;
 
-	dmaengine_terminate_all(tup->tx_dma_chan);
 	dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
+	dmaengine_terminate_all(tup->tx_dma_chan);
 	count = tup->tx_bytes_requested - state.residue;
 	async_tx_ack(tup->tx_dma_desc);
 	uart_xmit_advance(&tup->uport, count);
@@ -763,8 +763,8 @@ static void tegra_uart_terminate_rx_dma(struct tegra_uart_port *tup)
 		return;
 	}
 
-	dmaengine_terminate_all(tup->rx_dma_chan);
 	dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
+	dmaengine_terminate_all(tup->rx_dma_chan);
 
 	tegra_uart_rx_buffer_push(tup, state.residue);
 	tup->rx_dma_active = false;
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 8+ messages in thread
* Re: [PATCH] serial: tegra: read DMA status before terminating
  2022-10-18  6:25 ` Kartik
@ 2022-10-18  6:38   ` Greg KH
  2022-10-18  6:55     ` Kartik
  0 siblings, 1 reply; 8+ messages in thread
From: Greg KH @ 2022-10-18  6:38 UTC (permalink / raw)
  To: Kartik
  Cc: ldewangan, jirislaby, thierry.reding, jonathanh, swarren,
	akhilrajeev, linux-serial, linux-tegra, linux-kernel

On Tue, Oct 18, 2022 at 11:55:11AM +0530, Kartik wrote:
> To get the valid data, read DMA status before terminating the DMA. As
> dmaengine_terminate_all() deletes the DMA desc.
> 
> Fixes: e9ea096dd225 ("serial: tegra: add serial driver")
> 
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> Signed-off-by: Kartik <kkartik@nvidia.com>
> ---
>  drivers/tty/serial/serial-tegra.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Why send this twice?

confused,

greg k-h

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH] serial: tegra: read DMA status before terminating
  2022-10-18  6:38   ` Greg KH
@ 2022-10-18  6:55     ` Kartik
  2022-10-18  7:02       ` Greg KH
  0 siblings, 1 reply; 8+ messages in thread
From: Kartik @ 2022-10-18  6:55 UTC (permalink / raw)
  To: gregkh
  Cc: akhilrajeev, jirislaby, jonathanh, kkartik, ldewangan,
	linux-kernel, linux-serial, linux-tegra, swarren, thierry.reding

On Tue, Oct 18, 2022 at 12:08, Greg KH wrote:
> Why send this twice?
> 
> confused,

Hi Greg,

I made a mistake in my "git send-email" and the patch got posted twice.

Regards,
Kartik

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH] serial: tegra: read DMA status before terminating
  2022-10-18  6:55     ` Kartik
@ 2022-10-18  7:02       ` Greg KH
  2022-10-18  7:21         ` Kartik
  0 siblings, 1 reply; 8+ messages in thread
From: Greg KH @ 2022-10-18  7:02 UTC (permalink / raw)
  To: Kartik
  Cc: akhilrajeev, jirislaby, jonathanh, ldewangan, linux-kernel,
	linux-serial, linux-tegra, swarren, thierry.reding

On Tue, Oct 18, 2022 at 12:25:16PM +0530, Kartik wrote:
> On Tue, Oct 18, 2022 at 12:08, Greg KH wrote:
> > Why send this twice?
> > 
> > confused,
> 
> Hi Greg,
> 
> I made a mistake in my "git send-email" and the patch got posted twice.

So which one is correct?

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH] serial: tegra: read DMA status before terminating
  2022-10-18  7:02       ` Greg KH
@ 2022-10-18  7:21         ` Kartik
  0 siblings, 0 replies; 8+ messages in thread
From: Kartik @ 2022-10-18  7:21 UTC (permalink / raw)
  To: gregkh
  Cc: akhilrajeev, jirislaby, jonathanh, kkartik, ldewangan,
	linux-kernel, linux-serial, linux-tegra, swarren, thierry.reding

On Tue, Oct 18, 2022 at 12:32, Greg KH wrote:
> So which one is correct?
They are basically the same patch. I goofed up while sending it.
Please ignore the previous patch.

Regards,
Kartik

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH] serial: tegra: read DMA status before terminating
  2022-10-18  6:25 [PATCH] serial: tegra: read DMA status before terminating Kartik
  2022-10-18  6:25 ` Kartik
@ 2022-10-18 13:18 ` Jon Hunter
  2022-10-18 13:33   ` Kartik
  1 sibling, 1 reply; 8+ messages in thread
From: Jon Hunter @ 2022-10-18 13:18 UTC (permalink / raw)
  To: Kartik, ldewangan, gregkh, jirislaby, thierry.reding, swarren,
	akhilrajeev, linux-serial, linux-tegra, linux-kernel


On 18/10/2022 07:25, Kartik wrote:
> To get the valid data, read DMA status before terminating the DMA. As
> dmaengine_terminate_all() deletes the DMA desc.
> 
> Fixes: e9ea096dd225 ("serial: tegra: add serial driver")
> 
> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
> Signed-off-by: Kartik <kkartik@nvidia.com>
> ---
>   drivers/tty/serial/serial-tegra.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
> index b7170cb9a544..2779b4491f02 100644
> --- a/drivers/tty/serial/serial-tegra.c
> +++ b/drivers/tty/serial/serial-tegra.c
> @@ -619,8 +619,8 @@ static void tegra_uart_stop_tx(struct uart_port *u)
>   	if (tup->tx_in_progress != TEGRA_UART_TX_DMA)
>   		return;
>   
> -	dmaengine_terminate_all(tup->tx_dma_chan);
>   	dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
> +	dmaengine_terminate_all(tup->tx_dma_chan);

The change looks fine to me, but on further review of other similar 
drivers I see that they pause first ...

  dmaengine_pause(tup->tx_dma_chan);
  dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
  dmaengine_terminate_all(tup->tx_dma_chan);

This makes sense so that when we calculate the amount of the data 
transferred we get the exact amount. Can we add a pause while we are at it?

Thanks!
Jon

-- 
nvpublic

^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH] serial: tegra: read DMA status before terminating
  2022-10-18 13:18 ` Jon Hunter
@ 2022-10-18 13:33   ` Kartik
  0 siblings, 0 replies; 8+ messages in thread
From: Kartik @ 2022-10-18 13:33 UTC (permalink / raw)
  To: jonathanh
  Cc: akhilrajeev, gregkh, jirislaby, kkartik, ldewangan, linux-kernel,
	linux-serial, linux-tegra, swarren, thierry.reding

> The change looks fine to me, but on further review of other similar 
> drivers I see that they pause first ...
> 
>   dmaengine_pause(tup->tx_dma_chan);
>   dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
>   dmaengine_terminate_all(tup->tx_dma_chan);
> 
> This makes sense so that when we calculate the amount of the data 
> transferred we get the exact amount. Can we add a pause while we are at it?
> 
> Thanks!
> Jon

I agree.. I will include this in v2.

Regards,
Kartik

^ permalink raw reply	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2022-10-18 13:34 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-10-18  6:25 [PATCH] serial: tegra: read DMA status before terminating Kartik
2022-10-18  6:25 ` Kartik
2022-10-18  6:38   ` Greg KH
2022-10-18  6:55     ` Kartik
2022-10-18  7:02       ` Greg KH
2022-10-18  7:21         ` Kartik
2022-10-18 13:18 ` Jon Hunter
2022-10-18 13:33   ` Kartik

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