On Sat, Nov 5, 2011 at 10:25 AM, Kukjin Kim <kgene.kim@xxxxxxxxxxx> wrote:
> MyungJoo Ham wrote:
>>
>> Hello,
>>
> Hi,
>
> I got the comments from Jaecheol Lee but his mail client has some problem so
> I'm sending instead.
>
>> On Wed, Nov 2, 2011 at 9:43 PM, Kukjin Kim <kgene.kim@xxxxxxxxxxx> wrote:
>> []
>> > +static void __init set_volt_table(void)
>> > +{
>> > + unsigned int tmp, i, asv_group = 0;
>> > +
>> > + tmp = __raw_readl(S5P_INFORM2);
>>
>> As I've mentioned in the ASV patch thread, do we really need to use an
>> INFORM register simply to save the id of supported voltage ranges?
>>
>> Why aren't we using an extern variable here? For example, "extern int
>> asv_group_id;" and define it at "asv.h" or somewhere else.
>>
>> At reboot, we are going to init ASV driver and will get the ASV value
>> again; thus, we don't need to use such a preserving register anyway.
>> At suspend/resume, the value in RAM does not disappear and the IPL
>> does not care this value; thus, it is meaningless to use INFORM2 for
>> this value.
>>
> ASV feature had been implemented in bootloader hence inform register was
> used to return the result value to cpufreq driver. If there is no problem to
> use the inform register why don't you keep this manner.
The concern is that
1. INFORM2 is a hard-to-read special register, not a reader-friendly
variable. A variable such as "extern int exynos4_asv_value" is much
easier for readers.
2. We are not using such a special-purpose bootloader and we can't
sure which bootloader is being used often.
3. Other device drivers will start using this ASV value (such as
/drivers/devfreq/exynos4210-busfreq.c). Having such machine/bootloader
specific register addresses in a device driver really doesn't look
good. Also, we will be able to share the variable name for other SoCs
depending on how we name it; Exynos4xxx or more.
Thank you.
Cheers!
MyungJoo
>
> (snip)
>
> Thanks.
>
> Best regards,
> Kgene.
> --
> Kukjin Kim <kgene.kim@xxxxxxxxxxx>, Senior Engineer,
> SW Solution Development Team, Samsung Electronics Co., Ltd.
>
>
--
MyungJoo Ham, Ph.D.
Mobile Software Platform Lab, DMC Business, Samsung Electronics
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