Onenand Reset IOBE bit in SYS_CFG register in onenand_release

Hi,

> Interesting, share interrupt pin between OneNAND and NAND.
> Do you check the performance gain from interrupt use?
> Even though there's code to use interrupt wait, in my board, there's
> no performance gain.
I think that the interrupt mode will help when there is high load on
the CPU. Will run tests in interrupt and polling mode in two
scenarios. 1. Copy of a large file to ONENAND with no CPU load. 2.
Copy of a Large file to ONENAND with an infinite loop running in the
background - this generates CPU load. Little bit busy today but will
run it and mail the results by tomorrow. In my opinion Scenario 2
should give better results in interrupt mode.

> Anyway follow patch fix your problem, I'm okay to apply.
> except one code style issue. please place curly brace '{' after if statement
>

Thanks a lot! Resending the patch:

Regards
Gaurav Singh

Hi,

> I think that the interrupt mode will help when there is high load on
> the CPU. Will run tests in interrupt and polling mode in two
> scenarios. 1. Copy of a large file to ONENAND with no CPU load. 2.
> Copy of a Large file to ONENAND with an infinite loop running in the
> background - this generates CPU load. Little bit busy today but will
> run it and mail the results by tomorrow. In my opinion Scenario 2
> should give better results in interrupt mode.

Interrupt mode is giving better results than the normal polling mode.
In terms of time taken to copy both the modes are taking the same time
for both scenarios. But in the case of interrupt mode the CPU usage is
coming out to be less as indicated by top. Average CPU usage in
Scenario 2 is 40% for interrupt mode whereas it is 57% for polling
mode.

 diff --git a/drivers/mtd/onenand/onenand_base.c
 b/drivers/mtd/onenand/onenand_base.c
 index 0e168d8..9b2f9aa 100644
 --- a/drivers/mtd/onenand/onenand_base.c
 +++ b/drivers/mtd/onenand/onenand_base.c
 @@ -2728,6 +2728,13 @@ void onenand_release(struct mtd_info *mtd)
        /* Deregister partitions */
        del_mtd_partitions (mtd);
  #endif
 +       /* Reset the IOBE bit in SYS_CFG Register */
 +        if ( this->wait == onenand_interrupt_wait ) {
 +               int syscfg = this->read_word(this->base +
ONENAND_REG_SYS_CFG1);
 +               syscfg &= ~ONENAND_SYS_CFG1_IOBE;
 +               this->write_word(syscfg, this->base + ONENAND_REG_SYS_CFG1);
 +       }
        /* Deregister the device */
        del_mtd_device (mtd);

Regards
Gaurav Singh

On Tue, Apr 28, 2009 at 12:54 PM, Gaurav Singh <gausinghnsit@gmail.com> wrote:
> Hi,
>
>> I think that the interrupt mode will help when there is high load on
>> the CPU. Will run tests in interrupt and polling mode in two
>> scenarios. 1. Copy of a large file to ONENAND with no CPU load. 2.
>> Copy of a Large file to ONENAND with an infinite loop running in the
>> background - this generates CPU load. Little bit busy today but will
>> run it and mail the results by tomorrow. In my opinion Scenario 2
>> should give better results in interrupt mode.
>
> Interrupt mode is giving better results than the normal polling mode.
> In terms of time taken to copy both the modes are taking the same time
> for both scenarios. But in the case of interrupt mode the CPU usage is
> coming out to be less as indicated by top. Average CPU usage in
> Scenario 2 is 40% for interrupt mode whereas it is 57% for polling
> mode.
>

Thank you for info.
Right, in view of CPU interrupt mode is better, but not much
performance gain. overall read/write performance.

Thank you,
Kyungmin Park