[PATCH 2/5] t210: do not enable PLLE and UPHY PLL HW PWRSEQ

JC Kuo jckuo at nvidia.com
Wed Mar 18 02:44:45 CET 2020

Please refer to "Notes" section in p1337 of Tegra_X1_TRM_DP07225001_v1.3p.pdf.
There are some implementation considerations for boot software.


On 3/18/20 1:44 AM, Tom Warren wrote:
> -----Original Message-----
> From: Stephen Warren <swarren at wwwdotorg.org> 
> Sent: Tuesday, March 17, 2020 10:30 AM
> To: Tom Warren <TWarren at nvidia.com>
> Cc: u-boot at lists.denx.de; Jui Chang Kuo <jckuo at nvidia.com>
> Subject: Re: [PATCH 2/5] t210: do not enable PLLE and UPHY PLL HW PWRSEQ
> External email: Use caution opening links or attachments
> On 3/16/20 1:40 PM, twarren at nvidia.com wrote:
>> From: JC Kuo <jckuo at nvidia.com>
>> This commit removes the programming sequence that enables PLLE and 
>> UPHY PLL hardware power sequencers. Per TRM, boot software should 
>> enable PLLE and UPHY PLLs in software controlled power-on state and 
>> should power down PLL before jumping into kernel or the next stage boot software.
>> Adds call to board_cleanup_before_linux to facilitate this.
> This directly contradicts what's in Tegra_X1_TRM_DP07225001_v1.3p.pdf,
> pages 1340/1341, which is what the code currently implements. Was a newer internal-only TRM published that changed the recommended programming flow?
> [Tom] JC wrote this, I'll let him answer, but I'll check my TRM to see what the most recent version is. This code is exactly what we have in downstream T210 U-Boot.

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