-----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]
I'm thinking in two scenarios :
- 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
- 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@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot