Re: implementing "suspend to ram" on cortex A8 based on linux 3.0.8

Re: implementing "suspend to ram" on cortex A8 based on linux 3.0.8

[Fabio Estevam]

On Wed, Mar 7, 2012 at 12:05 PM, yang gqyang <hustgqyang@gmail.com> wrote:
> dear all:
> I am working on arm cortex a8 now, trying to implement "suspend to ram"
> based on linux 3.0.8.

Which CPU exactly are you using?

Re: implementing "suspend to ram" on cortex A8 based on linux 3.0.8

[yang gqyang]

 Thanks for your comment.
 Finally, i find out that i made a mistake.  The uart(8250) have not been
 restore after resume, instead, it use the configuration got from boot. The
 uart have not been restored correctly, so that "ls" can not output result
 correctly resulting in it seems that the busybox can not work correctly.
 Now, i still have a question about the uart: why the "printk" can work
 correctly, but the "printf" not?

 Before this, i believe that the "printk" work correctly, then the uart
 work ok. but now, i  need more reconsidaration about
 the relation between the "printk", "printf" and "uart".
 Can anyone give me some suggestion? Any comment is welcome, thanks a
 lot.


> 在 2012年3月9日 下午10:08，Chenglie He <chengjie.he@linaro.org>写道：
>
>> Hi,
>>
>> I am doing this on A9, echo mem >/sys/power/state is right, will trigger
>> kernel to sleep.
>>
>> -jack

>
some recipient promote:
"The message contains HTML subpart, therefore we consider it SPAM or
Outlook Virus"
so i resend the email, hope it not disturb u. thanks a lot.

Re: implementing "suspend to ram" on cortex A8 based on linux 3.0.8

[Barry Song]

hi yang,

在 2012年3月10日 下午10:37，yang gqyang <hustgqyang@gmail.com> 写道：
>  Thanks for your comment.
>  Finally, i find out that i made a mistake.  The uart(8250) have not been
>  restore after resume, instead, it use the configuration got from boot. The
>  uart have not been restored correctly, so that "ls" can not output result
>  correctly resulting in it seems that the busybox can not work correctly.
>  Now, i still have a question about the uart: why the "printk" can work
>  correctly, but the "printf" not?
>
>  Before this, i believe that the "printk" work correctly, then the uart
>  work ok. but now, i  need more reconsidaration about
>  the relation between the "printk", "printf" and "uart".
>  Can anyone give me some suggestion? Any comment is welcome, thanks a
>  lot.

printk use "struct console" driver, it doesn't depend on a device node
for userspace.
printf actaully depends on uart_driver and a /dev/ttySx device node,
stdout and stderr are redirected to /dev/ttySx
uart is just a hardware which can be a tty or kernel console output.


>
>
-barry