[U-Boot] [PATCH 07/12] imx:mx6 Support LDO bypass

[Stefano Babic <sbabic@denx.de>]

Hi Tim,

On 10/02/2015 15:50, Tim Harvey wrote:
> On Tue, Feb 10, 2015 at 3:23 AM, Stefano Babic <sbabic@denx.de> wrote:
>>
>> Ok - with this explanation, I would try to understand how the changes
>> can be split. If the feature/change works for several boards, it makes
>> sense to have it common and general. If it is only for one board, must
>> flow into the board directory.
> 
> It should be common as there are several boards which use PMIC's and can use it.
> 

Fully agree.


>> I am quite lost. I have searched in kernel (current TOT), and I have not
>> found such property. Can you help me to understand ?
> 
> Right - you won't find it because its a Freescale vendor kernel
> implementation only. A hack if you ask me to avoid having to doing
> ldo-byapss the right way.

Exactly, this cannot flow into mainline.

> 
> Here are the threads that I know of regarding ldo-bypass in the
> kernel, where it needs to be:
> 
> https://lkml.org/lkml/2014/12/18/255
> https://lkml.org/lkml/2014/10/31/3

Thanks for pointing out !

> 
> Peng,
> 
> I think what you are trying to do here is to put the anatop regulators
> in bypass mode so that the Freescale vendor kernel leaves them
> bypassed (which is what the 3.10.x based vendor kernels supporting
> device-tree at http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git
> do). This is what the Freescale vendor U-Boot does and so they have
> created a horrible dependence between kernel and bootloader.
> 

You are perfectly right.

> Instead you may be interested in what I did for our BSP's that use the
> Freescale vendor kernel. Instead of touching U-Boot, I look for the
> fsl,ldo-bypass node in the kernel and enable it just like their
> bootloader would have:
> https://github.com/Gateworks/linux-imx6/commit/a1af6ac6f00b4da7c8a5656e8ff093d4ab5cadee
> 

Thanks - you are on the right direction ;-)

Best regards,
Stefano

-- 
=====================================================================
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================