[PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core DVFS.

[PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core DVFS.

[Thara Gopinath]

As per the current implementaion (u8*)&target_level is being passed
to freq_to_opp in set_opp. This would result in updating just the first
8 bits of a u32 variable. Later target_level is passed to
resource_set_opp_level as a u32 parameter. This maens
a. Initially target_level was 0xabcdefgh.
b. freq_to_opp updates the lower eight bits of target_level
to 0xXX. Now target_level = 0xabcdefXX.
c. We pass 0xabcdefXX as target_level to resource_set_opp_level
when we want to pass just 0xXX.
This is leading to some corrupted bookkeeping later on in the
dvfs path.

This patch ensures that target_level passed to resource_set_opp_level
is actually the level that is intended by freq_to_opp API.

Signed-off-by: Thara Gopinath <thara@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
---
 arch/arm/mach-omap2/resource34xx.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mach-omap2/resource34xx.c b/arch/arm/mach-omap2/resource34xx.c
index 3604a38..d2336d8 100644
--- a/arch/arm/mach-omap2/resource34xx.c
+++ b/arch/arm/mach-omap2/resource34xx.c
@@ -463,6 +463,7 @@ int set_opp(struct shared_resource *resp, u32 target_level)
 	} else if (resp == vdd2_resp) {
 		unsigned long req_l3_freq;
 		struct omap_opp *oppx = NULL;
+		u8 opp;
 
 		/* Convert the tput in KiB/s to Bus frequency in MHz */
 		req_l3_freq = (target_level * 1000)/4;
@@ -478,10 +479,11 @@ int set_opp(struct shared_resource *resp, u32 target_level)
 		/* uh uh.. no OPPs?? */
 		BUG_ON(IS_ERR(oppx));
 
-		ret = freq_to_opp((u8 *)&target_level, OPP_L3, req_l3_freq);
+		ret = freq_to_opp(&opp, OPP_L3, req_l3_freq);
 		/* we dont expect this to fail */
 		BUG_ON(ret);
 
+		target_level = opp;
 		ret = resource_set_opp_level(VDD2_OPP, target_level, 0);
 	}
 	return 0;
-- 
1.5.4.7

Re: [PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core DVFS.

[Menon, Nishanth]

Gopinath, Thara said the following on 02/18/2010 10:31 AM:
> As per the current implementaion (u8*)&target_level is being passed
> to freq_to_opp in set_opp. This would result in updating just the first
> 8 bits of a u32 variable. Later target_level is passed to
> resource_set_opp_level as a u32 parameter. This maens
> a. Initially target_level was 0xabcdefgh.
> b. freq_to_opp updates the lower eight bits of target_level
> to 0xXX. Now target_level = 0xabcdefXX.
> c. We pass 0xabcdefXX as target_level to resource_set_opp_level
> when we want to pass just 0xXX.
> This is leading to some corrupted bookkeeping later on in the
> dvfs path.
> 
> This patch ensures that target_level passed to resource_set_opp_level
> is actually the level that is intended by freq_to_opp API.

Thanks.. good catch.
[PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core 
DVFS.
Suggestion on the subject:
could you put it something like the following so that git-am will 
throw away PM-WIP-OPP?
[PATCH] [PM-WIP-OPP] omap3: pm: Fix wrong target level during core dvfs

?
Some suggestion below.

> 
> Signed-off-by: Thara Gopinath <thara@ti.com>
> Cc: Kevin Hilman <khilman@deeprootsystems.com>
> ---
>  arch/arm/mach-omap2/resource34xx.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/resource34xx.c b/arch/arm/mach-omap2/resource34xx.c
> index 3604a38..d2336d8 100644
> --- a/arch/arm/mach-omap2/resource34xx.c
> +++ b/arch/arm/mach-omap2/resource34xx.c
> @@ -463,6 +463,7 @@ int set_opp(struct shared_resource *resp, u32 target_level)
>  	} else if (resp == vdd2_resp) {
>  		unsigned long req_l3_freq;
>  		struct omap_opp *oppx = NULL;
> +		u8 opp;
>  
>  		/* Convert the tput in KiB/s to Bus frequency in MHz */
>  		req_l3_freq = (target_level * 1000)/4;
> @@ -478,10 +479,11 @@ int set_opp(struct shared_resource *resp, u32 target_level)
>  		/* uh uh.. no OPPs?? */
>  		BUG_ON(IS_ERR(oppx));
>  
If you do target_level = 0; here, the entire patch is a oneliner :)

> -		ret = freq_to_opp((u8 *)&target_level, OPP_L3, req_l3_freq);
> +		ret = freq_to_opp(&opp, OPP_L3, req_l3_freq);
>  		/* we dont expect this to fail */
>  		BUG_ON(ret);
>  
> +		target_level = opp;
>  		ret = resource_set_opp_level(VDD2_OPP, target_level, 0);
>  	}
>  	return 0;

-- 
Regards,
Nishanth Menon

RE: [PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core DVFS.

[Aguirre, Sergio]

Nishanth,

> -----Original Message-----
> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-
> owner@vger.kernel.org] On Behalf Of Menon, Nishanth
> Sent: Thursday, February 18, 2010 8:58 AM
> To: Gopinath, Thara
> Cc: linux-omap@vger.kernel.org; Kevin Hilman; Kristo Tero (Nokia-
> D/Tampere)
> Subject: Re: [PATCH] PM-WIP-OPP: Fixing wrong target level being passed
> during Core DVFS.
> 
> Gopinath, Thara said the following on 02/18/2010 10:31 AM:
> > As per the current implementaion (u8*)&target_level is being passed
> > to freq_to_opp in set_opp. This would result in updating just the first
> > 8 bits of a u32 variable. Later target_level is passed to
> > resource_set_opp_level as a u32 parameter. This maens
> > a. Initially target_level was 0xabcdefgh.
> > b. freq_to_opp updates the lower eight bits of target_level
> > to 0xXX. Now target_level = 0xabcdefXX.
> > c. We pass 0xabcdefXX as target_level to resource_set_opp_level
> > when we want to pass just 0xXX.
> > This is leading to some corrupted bookkeeping later on in the
> > dvfs path.
> >
> > This patch ensures that target_level passed to resource_set_opp_level
> > is actually the level that is intended by freq_to_opp API.
> 
> Thanks.. good catch.
> [PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core
> DVFS.
> Suggestion on the subject:
> could you put it something like the following so that git-am will
> throw away PM-WIP-OPP?
> [PATCH] [PM-WIP-OPP] omap3: pm: Fix wrong target level during core dvfs
> 
> ?
> Some suggestion below.
> 
> >
> > Signed-off-by: Thara Gopinath <thara@ti.com>
> > Cc: Kevin Hilman <khilman@deeprootsystems.com>
> > ---
> >  arch/arm/mach-omap2/resource34xx.c |    4 +++-
> >  1 files changed, 3 insertions(+), 1 deletions(-)
> >
> > diff --git a/arch/arm/mach-omap2/resource34xx.c b/arch/arm/mach-
> omap2/resource34xx.c
> > index 3604a38..d2336d8 100644
> > --- a/arch/arm/mach-omap2/resource34xx.c
> > +++ b/arch/arm/mach-omap2/resource34xx.c
> > @@ -463,6 +463,7 @@ int set_opp(struct shared_resource *resp, u32
> target_level)
> >  	} else if (resp == vdd2_resp) {
> >  		unsigned long req_l3_freq;
> >  		struct omap_opp *oppx = NULL;
> > +		u8 opp;
> >
> >  		/* Convert the tput in KiB/s to Bus frequency in MHz */
> >  		req_l3_freq = (target_level * 1000)/4;
> > @@ -478,10 +479,11 @@ int set_opp(struct shared_resource *resp, u32
> target_level)
> >  		/* uh uh.. no OPPs?? */
> >  		BUG_ON(IS_ERR(oppx));
> >
> If you do target_level = 0; here, the entire patch is a oneliner :)

Actually, IMHO will be even more clean, to standardize all OPP value passing to be u8.

Do you really need to be prepared for 2^32 opp values? ;)

Regards,
Sergio

> 
> > -		ret = freq_to_opp((u8 *)&target_level, OPP_L3, req_l3_freq);
> > +		ret = freq_to_opp(&opp, OPP_L3, req_l3_freq);
> >  		/* we dont expect this to fail */
> >  		BUG_ON(ret);
> >
> > +		target_level = opp;
> >  		ret = resource_set_opp_level(VDD2_OPP, target_level, 0);
> >  	}
> >  	return 0;
> 
> --
> Regards,
> Nishanth Menon
> --
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RE: [PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core DVFS.

[Menon, Nishanth]

> From: Aguirre, Sergio
> Sent: Tuesday, February 23, 2010 7:28 AM
> To: Menon, Nishanth; Gopinath, Thara
[...]
> >
> > >
> > > Signed-off-by: Thara Gopinath <thara@ti.com>
> > > Cc: Kevin Hilman <khilman@deeprootsystems.com>
> > > ---
> > >  arch/arm/mach-omap2/resource34xx.c |    4 +++-
> > >  1 files changed, 3 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/arch/arm/mach-omap2/resource34xx.c b/arch/arm/mach-
> > omap2/resource34xx.c
> > > index 3604a38..d2336d8 100644
> > > --- a/arch/arm/mach-omap2/resource34xx.c
> > > +++ b/arch/arm/mach-omap2/resource34xx.c
> > > @@ -463,6 +463,7 @@ int set_opp(struct shared_resource *resp, u32
> > target_level)
> > >  	} else if (resp == vdd2_resp) {
> > >  		unsigned long req_l3_freq;
> > >  		struct omap_opp *oppx = NULL;
> > > +		u8 opp;
> > >
> > >  		/* Convert the tput in KiB/s to Bus frequency in MHz */
> > >  		req_l3_freq = (target_level * 1000)/4;
> > > @@ -478,10 +479,11 @@ int set_opp(struct shared_resource *resp, u32
> > target_level)
> > >  		/* uh uh.. no OPPs?? */
> > >  		BUG_ON(IS_ERR(oppx));
> > >
> > If you do target_level = 0; here, the entire patch is a oneliner :)
> 
> Actually, IMHO will be even more clean, to standardize all OPP value
> passing to be u8.
> 
> Do you really need to be prepared for 2^32 opp values? ;)
> 
Using OPP ID has to be completely removed from resource34xx.c -> this action is still pending. In this case, using u8 OR initing the target_level to 0 has the same impact. Why add code that will be removed later on anyways?

Regards,
Nishanth Menon

RE: [PATCH] PM-WIP-OPP: Fixing wrong target level being passed during Core DVFS.

[Aguirre, Sergio]

> -----Original Message-----
> From: Menon, Nishanth
> Sent: Monday, February 22, 2010 11:31 PM
> To: Aguirre, Sergio; Gopinath, Thara
> Cc: linux-omap@vger.kernel.org; Kevin Hilman; Kristo Tero (Nokia-
> D/Tampere)
> Subject: RE: [PATCH] PM-WIP-OPP: Fixing wrong target level being passed
> during Core DVFS.
> 
> > From: Aguirre, Sergio
> > Sent: Tuesday, February 23, 2010 7:28 AM
> > To: Menon, Nishanth; Gopinath, Thara
> [...]
> > >
> > > >
> > > > Signed-off-by: Thara Gopinath <thara@ti.com>
> > > > Cc: Kevin Hilman <khilman@deeprootsystems.com>
> > > > ---
> > > >  arch/arm/mach-omap2/resource34xx.c |    4 +++-
> > > >  1 files changed, 3 insertions(+), 1 deletions(-)
> > > >
> > > > diff --git a/arch/arm/mach-omap2/resource34xx.c b/arch/arm/mach-
> > > omap2/resource34xx.c
> > > > index 3604a38..d2336d8 100644
> > > > --- a/arch/arm/mach-omap2/resource34xx.c
> > > > +++ b/arch/arm/mach-omap2/resource34xx.c
> > > > @@ -463,6 +463,7 @@ int set_opp(struct shared_resource *resp, u32
> > > target_level)
> > > >  	} else if (resp == vdd2_resp) {
> > > >  		unsigned long req_l3_freq;
> > > >  		struct omap_opp *oppx = NULL;
> > > > +		u8 opp;
> > > >
> > > >  		/* Convert the tput in KiB/s to Bus frequency in MHz */
> > > >  		req_l3_freq = (target_level * 1000)/4;
> > > > @@ -478,10 +479,11 @@ int set_opp(struct shared_resource *resp, u32
> > > target_level)
> > > >  		/* uh uh.. no OPPs?? */
> > > >  		BUG_ON(IS_ERR(oppx));
> > > >
> > > If you do target_level = 0; here, the entire patch is a oneliner :)
> >
> > Actually, IMHO will be even more clean, to standardize all OPP value
> > passing to be u8.
> >
> > Do you really need to be prepared for 2^32 opp values? ;)
> >
> Using OPP ID has to be completely removed from resource34xx.c -> this
> action is still pending. In this case, using u8 OR initing the
> target_level to 0 has the same impact. Why add code that will be removed
> later on anyways?

Well, I'm not proposing for code addition, but to fix that code just by changing opp level parameters to u8, instead of u32, like this:

-int set_opp(struct shared_resource *resp, u32 target_level)
+int set_opp(struct shared_resource *resp, u8 target_level)

If you're going to replace all this in the near future, then it's understandable to hold even this patch (target_level = 0).

Regards,
Sergio
> 
> Regards,
> Nishanth Menon