On Fri, May 4, 2012 at 2:42 PM, AnilKumar, Chimata <anilkumar@xxxxxx> wrote:
> On Thu, Apr 26, 2012 at 23:10:36, J, KEERTHY wrote:
>> From: Jean Pihet <j-pihet@xxxxxx>
>>
>> Now that omap_test_timeout is only accessible from mach-omap2/,
>> introduce a similar function for SR.
>>
>> This change makes the SmartReflex implementation ready for the move
>> to drivers/.
>>
>> Signed-off-by: Jean Pihet <j-pihet@xxxxxx>
>> Signed-off-by: J Keerthy <j-keerthy@xxxxxx>
>> ---
>> arch/arm/mach-omap2/smartreflex.c | 12 ++++++------
>> include/linux/power/smartreflex.h | 23 ++++++++++++++++++++++-
>> 2 files changed, 28 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/smartreflex.c b/arch/arm/mach-omap2/smartreflex.c
>> index d859277..acef08d 100644
>> --- a/arch/arm/mach-omap2/smartreflex.c
>> +++ b/arch/arm/mach-omap2/smartreflex.c
>> @@ -289,9 +289,9 @@ static void sr_v1_disable(struct omap_sr *sr)
>> * Wait for SR to be disabled.
>> * wait until ERRCONFIG.MCUDISACKINTST = 1. Typical latency is 1us.
>> */
>> - omap_test_timeout((sr_read_reg(sr, ERRCONFIG_V1) &
>> - ERRCONFIG_MCUDISACKINTST), SR_DISABLE_TIMEOUT,
>> - timeout);
>> + sr_test_cond_timeout((sr_read_reg(sr, ERRCONFIG_V1) &
>> + ERRCONFIG_MCUDISACKINTST), SR_DISABLE_TIMEOUT,
>> + timeout);
>>
>> if (timeout >= SR_DISABLE_TIMEOUT)
>> dev_warn(&sr->pdev->dev, "%s: Smartreflex disable timedout\n",
>> @@ -334,9 +334,9 @@ static void sr_v2_disable(struct omap_sr *sr)
>> * Wait for SR to be disabled.
>> * wait until IRQSTATUS.MCUDISACKINTST = 1. Typical latency is 1us.
>> */
>> - omap_test_timeout((sr_read_reg(sr, IRQSTATUS) &
>> - IRQSTATUS_MCUDISABLEACKINT), SR_DISABLE_TIMEOUT,
>> - timeout);
>> + sr_test_cond_timeout((sr_read_reg(sr, IRQSTATUS) &
>> + IRQSTATUS_MCUDISABLEACKINT), SR_DISABLE_TIMEOUT,
>> + timeout);
>>
>> if (timeout >= SR_DISABLE_TIMEOUT)
>> dev_warn(&sr->pdev->dev, "%s: Smartreflex disable timedout\n",
>> diff --git a/include/linux/power/smartreflex.h b/include/linux/power/smartreflex.h
>> index 884eaee..78b795e 100644
>> --- a/include/linux/power/smartreflex.h
>> +++ b/include/linux/power/smartreflex.h
>> @@ -22,7 +22,7 @@
>>
>> #include <linux/types.h>
>> #include <linux/platform_device.h>
>> -
>> +#include <linux/delay.h>
>> #include <plat/voltage.h>
>>
>> /*
>> @@ -168,6 +168,27 @@ struct omap_sr {
>> };
>>
>> /**
>> + * test_cond_timeout - busy-loop, testing a condition
>> + * @cond: condition to test until it evaluates to true
>> + * @timeout: maximum number of microseconds in the timeout
>> + * @index: loop index (integer)
>> + *
>> + * Loop waiting for @cond to become true or until at least @timeout
>> + * microseconds have passed. To use, define some integer @index in the
>> + * calling code. After running, if @index == @timeout, then the loop has
>> + * timed out.
>> + *
>> + * Copied from omap_test_timeout */
>> +#define sr_test_cond_timeout(cond, timeout, index) \
>> +({ \
>> + for (index = 0; index < timeout; index++) { \
>> + if (cond) \
>> + break; \
>> + udelay(1); \
>> + } \
>> +})
>
> I think we can use time_after()/time_before() APIs for timeout and cpu_relax() for
> tight loops instead of udelay().
cpu_relax() changes the priority everytime to low and will yield to
another thread.
Considering that we are checking the condition every microsecond does it make
some saving using cpu_relax().
>
> Regards
> AnilKumar
--
Regards and Thanks,
Keerthy
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