-----Original Message----- From: Enric Balletbò i Serra [mailto:eballetbo@gmail.com] Sent: Friday, November 19, 2010 6:30 PM To: Premi, Sanjeev Cc: u-boot@lists.denx.de; Steve Sakoman Subject: Re: [U-Boot] AM/DM37X How to configure registers to get 1000MHz

Hi,

Thanks for your reply

2010/11/19 Premi, Sanjeev premi@ti.com:

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-----Original Message----- From: u-boot-bounces@lists.denx.de [mailto:u-boot-bounces@lists.denx.de] On Behalf Of Enric Balletbò i Serra Sent: Friday, November 19, 2010 2:42 PM To: u-boot@lists.denx.de; Steve Sakoman Subject: [U-Boot] AM/DM37X How to configure registers to

get 1000MHz

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Hi all,

I would ask a question, maybe someone can help, which is the better way to configure the PRCM registers to get 1000MHz on AM/DM37X processor ?

You need set the multipliers and dividers apprioriately -

based on the

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sysclk.

Would help to understand the context of "better"?

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.

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?

Thanks in advance, Enric

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~sanjeev

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

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

[snip]...[snip]

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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

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...

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

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Thanks in advance,    Enric

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~sanjeev

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