Hello,
The format of calling resource_rerquest for vdd2 opp setting is
resource_request("vdd2_opp", dev, r);
where r is the throughput.
Example, in set_opp, if vdd1 opp is >= 3, vdd2 opp is being set to 3.
The above means "resource_request" expects "targeted level"
for all types of OPP/Freq resources except for "vdd2_opp".
Only for vdd2_opp we need to give the "throughput required"
and not the "targeted level". Is that correct?
API needs to be generic. If my above understanding is correct,
why "resource_request" is expecting an unique kind of
input parameter, only for vdd2_opp resource?
Thanks,
V Charu Latha
_______________________________________
From: [email protected] [[email protected]] On
Behalf Of Varadarajan, Charu Latha
Sent: Thursday, September 17, 2009 2:55 PM
To: [email protected]
Subject: Issue with setting vdd2_opp level to 3 through OMAP3 SRF API's
Hello,
When trying to make "vdd2_opp" resource to "VDD2_OPP3" level using
"resource_request"(arch\arm\plat-omap\resource.c), it is observed that vdd2_opp
is always put to VDD2_OPP2 level.
Code Snippet:
For the above, set_opp() in arch\arm\mach-omap2\resource34xx.c is called with a
target level of 3. The code flow is as given below:
/*********************** Code Snippet Start****************************/
else if (resp == vdd2_resp) {
tput = target_level;
/* Convert the tput in KiB/s to Bus frequency in MHz */
req_l3_freq = (tput * 1000)/4;
for (ind = 2; ind <= MAX_VDD2_OPP; ind++){
if ((l3_opps + ind)->rate >= req_l3_freq) {
target_level = ind;
break;
}
}
/* Set the highest OPP possible */
if (ind > MAX_VDD2_OPP)
target_level = ind-1;
resource_set_opp_level(VDD2_OPP, target_level, 0);
}
/*********************** Code Snippet End****************************/
Analysis:
During execution,
tout = 3;
req_l3_freq = 750;
when ind = 2, if ((l3_opps + ind)->rate >= req_l3_freq) ==> (83M > 750) which
in turn makes target_level = 2.
Hence while requesting for target_level of 3, vdd2_opp is made to target_level
= 2, which is incorrect.
Issues observed:
The above code should have been made for mapping L3 freq 83MHz to VDD2_OPP2 and
L3 freq 166MHz to VDD2_OPP3. But the above code would always make vdd2_opp to
VDD2_OPP2 level. However, it is observed that, if we change the vdd2_opp to 3
using sysfs, it seems to be setting to level 3. I am wondering if there are any
issues with sysfs entries since same is working with resource frame work API's.
Please let me know if my understanding is wrong.
Thanks & Regards,
V Charu Latha
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