[U-Boot] AM/DM37X How to configure registers to get 1000MHz

[Premi, Sanjeev]

> -----Original Message-----
> From: Enric Balletbò i Serra [mailto:eballetbo at gmail.com] 
> Sent: Friday, November 19, 2010 6:43 PM
> To: Premi, Sanjeev
> Cc: u-boot at lists.denx.de; Steve Sakoman
> Subject: Re: [U-Boot] AM/DM37X How to configure registers to 
> get 1000MHz

[snip]...[snip]

> >>
> >> I'm thinking in two scenarios :
> >>
> >> 1. For OMAP35X there are devices that support 600MHz as 
> max frequency
> >> but others supports 720MHz, I want to set by default 600MHz and if
> >> device supports 720MHz change to this frequency.
> >
> > [sp] You can look at one of my patches on linux kernel to 
> identify the
> >     device capability for 600/720MHz.
> 
> I''ll do, thanks
> 
> >
> >> 2. For AM/DM37X, maybe I'm wrong, but the default frequency for
> >> AM/DM37X is set to 600MHz, Like OMAP35X i want to set default to
> >> 800MHz and i device supports change to 1000MHz.
> >
> > [sp] The device comes up at 600MHz for now, but there is no 
> limitation
> >     on device to go all the way to 1GHz.
> >
> >>
> >> Which is the better way to do this ?
> >
> > [sp] So, you are looking for common mechanism to go to 
> highest supported
> >     frequency. Right?
> 
> Yes, I think should be interesting for all OMAP35/AM/DM37 a 
> mechanism like this.

[sp] I am stuck is a critical activity for next few days; would be
     able to work on this only next week.

     However, if you could start on it, I have quick thought process
     here:
     1) Have a function that returns max supported freq for each device.
        - Function for OMAP35x can internally check the capability bit
        - While the one for AM37x would return 1GHz.

     2) There is a mapping table for freq. and corresponding M, N, M2
        values that can be used to pick select the right values.

     3) Such a table exists in ASM; I have an intent to make it more
        readable in C - but always goes low in priority.

     4) Another twist to 2) above can be use of env variable that gets
        pref. e.g. 37x support 1GHz; but you wantto still boot at 800MHz
        for some reason; then setting env var would make the function
        return 800 instead of 1000.

~sanjeev

> 
> >
> >>
> >> Thanks in advance,
> >>    Enric
> >>
> >> >
> >> > ~sanjeev
> >> >
> >> >>
> >> >> Thanks in advance,
> >> >>    Enric
> >> >> _______________________________________________
> >> >> U-Boot mailing list
> >> >> U-Boot at lists.denx.de
> >> >> http://lists.denx.de/mailman/listinfo/u-boot
> >> >>
> >>
>