* [PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case
@ 2016-10-06 22:13 Aaron Brice
2016-10-07 18:06 ` Stefan Agner
2016-10-10 11:12 ` Bhuvanchandra DV
0 siblings, 2 replies; 3+ messages in thread
From: Aaron Brice @ 2016-10-06 22:13 UTC (permalink / raw)
To: gregkh, jslaby, bhuvanchandra.dv, stefan
Cc: linux-serial, linux-kernel, linux-arm-kernel
In the case where head == 0 on the circular buffer, there should be one
DMA buffer, not two. The second zero-length buffer would break the
lpuart driver, transfer would never complete.
Signed-off-by: Aaron Brice <aaron.brice@datasoft.com>
---
drivers/tty/serial/fsl_lpuart.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index de9d510..76103f2 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -328,7 +328,7 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
sport->dma_tx_bytes = uart_circ_chars_pending(xmit);
- if (xmit->tail < xmit->head) {
+ if (xmit->tail < xmit->head || xmit->head == 0) {
sport->dma_tx_nents = 1;
sg_init_one(sgl, xmit->buf + xmit->tail, sport->dma_tx_bytes);
} else {
@@ -359,7 +359,6 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
sport->dma_tx_in_progress = true;
sport->dma_tx_cookie = dmaengine_submit(sport->dma_tx_desc);
dma_async_issue_pending(sport->dma_tx_chan);
-
}
static void lpuart_dma_tx_complete(void *arg)
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case
2016-10-06 22:13 [PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case Aaron Brice
@ 2016-10-07 18:06 ` Stefan Agner
2016-10-10 11:12 ` Bhuvanchandra DV
1 sibling, 0 replies; 3+ messages in thread
From: Stefan Agner @ 2016-10-07 18:06 UTC (permalink / raw)
To: Aaron Brice, gregkh
Cc: jslaby, bhuvanchandra.dv, linux-serial, linux-kernel, linux-arm-kernel
On 2016-10-06 15:13, Aaron Brice wrote:
> In the case where head == 0 on the circular buffer, there should be one
> DMA buffer, not two. The second zero-length buffer would break the
> lpuart driver, transfer would never complete.
That looks right, and seems to work fine here:
Acked-by: Stefan Agner <stefan@agner.ch>
Tested-by: Stefan Agner <stefan@agner.ch>
@Greg, would be good if this would still make it into 4.9.
--
Stefan
>
> Signed-off-by: Aaron Brice <aaron.brice@datasoft.com>
> ---
> drivers/tty/serial/fsl_lpuart.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index de9d510..76103f2 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -328,7 +328,7 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
>
> sport->dma_tx_bytes = uart_circ_chars_pending(xmit);
>
> - if (xmit->tail < xmit->head) {
> + if (xmit->tail < xmit->head || xmit->head == 0) {
> sport->dma_tx_nents = 1;
> sg_init_one(sgl, xmit->buf + xmit->tail, sport->dma_tx_bytes);
> } else {
> @@ -359,7 +359,6 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
> sport->dma_tx_in_progress = true;
> sport->dma_tx_cookie = dmaengine_submit(sport->dma_tx_desc);
> dma_async_issue_pending(sport->dma_tx_chan);
> -
> }
>
> static void lpuart_dma_tx_complete(void *arg)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case
2016-10-06 22:13 [PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case Aaron Brice
2016-10-07 18:06 ` Stefan Agner
@ 2016-10-10 11:12 ` Bhuvanchandra DV
1 sibling, 0 replies; 3+ messages in thread
From: Bhuvanchandra DV @ 2016-10-10 11:12 UTC (permalink / raw)
To: Aaron Brice, gregkh, jslaby, stefan
Cc: linux-serial, linux-kernel, linux-arm-kernel
On 10/07/16 03:43, Aaron Brice wrote:
> In the case where head == 0 on the circular buffer, there should be one
> DMA buffer, not two. The second zero-length buffer would break the
> lpuart driver, transfer would never complete.
Tested-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
>
> Signed-off-by: Aaron Brice <aaron.brice@datasoft.com>
> ---
> drivers/tty/serial/fsl_lpuart.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index de9d510..76103f2 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -328,7 +328,7 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
>
> sport->dma_tx_bytes = uart_circ_chars_pending(xmit);
>
> - if (xmit->tail < xmit->head) {
> + if (xmit->tail < xmit->head || xmit->head == 0) {
> sport->dma_tx_nents = 1;
> sg_init_one(sgl, xmit->buf + xmit->tail, sport->dma_tx_bytes);
> } else {
> @@ -359,7 +359,6 @@ static void lpuart_dma_tx(struct lpuart_port *sport)
> sport->dma_tx_in_progress = true;
> sport->dma_tx_cookie = dmaengine_submit(sport->dma_tx_desc);
> dma_async_issue_pending(sport->dma_tx_chan);
> -
> }
>
> static void lpuart_dma_tx_complete(void *arg)
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-10-10 15:51 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-10-06 22:13 [PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case Aaron Brice
2016-10-07 18:06 ` Stefan Agner
2016-10-10 11:12 ` Bhuvanchandra DV
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).