Re: [U-Boot] [PATCH 6/8] Adds wait to atmel_usart serial_init function

2011-07-04 Thread Reinhard Meyer 
Dear Alex Waterman,
> Adds a short busy loop wait to the atmel_usart.c serial_init()
> function.
> 
> Signed-off-by: Alex Waterman 
> ---
>  drivers/serial/atmel_usart.c |6 ++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
> index e326b2b..e355706 100644
> --- a/drivers/serial/atmel_usart.c
> +++ b/drivers/serial/atmel_usart.c
> @@ -47,6 +47,8 @@ void serial_setbrg(void)
>  
>  int serial_init(void)
>  {
> +
> + volatile int i = 0;
>   atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
>  
>   writel(USART3_BIT(RSTRX) | USART3_BIT(RSTTX), &usart->cr);
> @@ -61,6 +63,10 @@ int serial_init(void)
>  | USART3_BF(NBSTOP, USART3_NBSTOP_1)),
>  &usart->mr);
>  
> + /* Short wait to let the serial port init. */
> + for (; i < 1; i++)
> + ;
> +
>   return 0;
>  }

1. Why is this delay needed in the first place?
Apparently it has not been required before.

2. Such a delay loop is highly dependant on toolchain,
cache and page situation and processor speed. It can not be
accepted as a solution. If a delay is really required here
and cannot be substituting by reading the UARTs status
register, udelay() must be used.

Best Regards,
Reinhard
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Re: [U-Boot] [PATCH 6/8] Adds wait to atmel_usart serial_init function

2011-07-01 Thread Albert ARIBAUD 
Hi Alex,

Le 01/07/2011 14:37, Alex Waterman a écrit :
>
>> Why 'volatile'? Also, there shouldn't be an empty line before it but 
>> there should be one after it...
> I used a volatile to prevent the compiler from optimizing out the (normally) 
> useless loop. Is there a cleaner way to do this?

If the board supports udelay(), you should use that instead of a loop.

> Best regards,
> Alex

Amicalement,
-- 
Albert.
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Re: [U-Boot] [PATCH 6/8] Adds wait to atmel_usart serial_init function

2011-07-01 Thread Alex Waterman 

>Why 'volatile'? Also, there shouldn't be an empty line before it but there 
> should be one after it...
I used a volatile to prevent the compiler from optimizing out the (normally) 
useless loop. Is there a cleaner way to do this?

Best regards,
Alex

-- 
Alex Waterman
Computer Engineer
Phone: 215-896-4920
Email: awater...@dawning.com

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Re: [U-Boot] [PATCH 6/8] Adds wait to atmel_usart serial_init function

2011-07-01 Thread Sergei Shtylyov 
Hello.

On 30-06-2011 23:33, Alex Waterman wrote:

> Adds a short busy loop wait to the atmel_usart.c serial_init()
> function.

> Signed-off-by: Alex Waterman

> diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
> index e326b2b..e355706 100644
> --- a/drivers/serial/atmel_usart.c
> +++ b/drivers/serial/atmel_usart.c
> @@ -47,6 +47,8 @@ void serial_setbrg(void)
>
>   int serial_init(void)
>   {
> +
> + volatile int i = 0;

Why 'volatile'? Also, there shouldn't be an empty line before it but there 
should be one after it...

>   atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
>
>   writel(USART3_BIT(RSTRX) | USART3_BIT(RSTTX),&usart->cr);
> @@ -61,6 +63,10 @@ int serial_init(void)
>  | USART3_BF(NBSTOP, USART3_NBSTOP_1)),
>   &usart->mr);
>
> + /* Short wait to let the serial port init. */
> + for (; i < 1; i++)
> + ;
> +
>   return 0;
>   }

WBR, Sergei
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[U-Boot] [PATCH 6/8] Adds wait to atmel_usart serial_init function

2011-06-30 Thread Alex.Waterman.awaterman 
From: Alex Waterman 

Adds a short busy loop wait to the atmel_usart.c serial_init()
function.

Signed-off-by: Alex Waterman 
---
 drivers/serial/atmel_usart.c |6 ++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
index e326b2b..e355706 100644
--- a/drivers/serial/atmel_usart.c
+++ b/drivers/serial/atmel_usart.c
@@ -47,6 +47,8 @@ void serial_setbrg(void)
 
 int serial_init(void)
 {
+
+   volatile int i = 0;
atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
 
writel(USART3_BIT(RSTRX) | USART3_BIT(RSTTX), &usart->cr);
@@ -61,6 +63,10 @@ int serial_init(void)
   | USART3_BF(NBSTOP, USART3_NBSTOP_1)),
   &usart->mr);
 
+   /* Short wait to let the serial port init. */
+   for (; i < 1; i++)
+   ;
+
return 0;
 }
 
-- 
1.7.4.4

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[U-Boot] [PATCH 6/8] Adds wait to atmel_usart serial_init function

2011-06-30 Thread Alex Waterman 
Adds a short busy loop wait to the atmel_usart.c serial_init()
function.

Signed-off-by: Alex Waterman 
---
 drivers/serial/atmel_usart.c |6 ++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/atmel_usart.c b/drivers/serial/atmel_usart.c
index e326b2b..e355706 100644
--- a/drivers/serial/atmel_usart.c
+++ b/drivers/serial/atmel_usart.c
@@ -47,6 +47,8 @@ void serial_setbrg(void)
 
 int serial_init(void)
 {
+
+   volatile int i = 0;
atmel_usart3_t *usart = (atmel_usart3_t *)CONFIG_USART_BASE;
 
writel(USART3_BIT(RSTRX) | USART3_BIT(RSTTX), &usart->cr);
@@ -61,6 +63,10 @@ int serial_init(void)
   | USART3_BF(NBSTOP, USART3_NBSTOP_1)),
   &usart->mr);
 
+   /* Short wait to let the serial port init. */
+   for (; i < 1; i++)
+   ;
+
return 0;
 }
 
-- 
1.7.4.4

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