Re: [PATCH 2/2] usb: dwc3: Added a property to set GFLADJ register

[John Youn]

On 9/12/2016 8:30 AM, Rob Herring wrote:
> On Thu, Sep 01, 2016 at 02:32:33PM -0700, John Youn wrote:
>> From: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
>>
>> Added gfladj variable to control the core behavior with respect to
>> SOF, ITP, and frame timer functionality.
>>
>> Currently there is dwc->fladj that holds a single field in GFLADJ
>> register (GFLADJ.GFLADJ_30MHZ). A new variable gfladj is added to
>> dwc structure to allow setting of the entire GFLADJ register. If
>> dwc->gfladj is set, then it has a higher priority than dwc->fladj
>> when writing to the GFLADJ register.
> 
> I'm not a fan of magic register values for DT properties.
> 

Sure. Felipe gave the same feedback. We'll fix it.

> How many fields in this register that you will ever need to touch?
> 
>> Synopsys HW setup (HAPS DX and phy board) requires a preset to this
>> register to improve interoperablitity. For example, the value for
>> GFLADJ_REFCLK_LPM_SEL should be set to 0 with ref_clk period of 50.
> 
> This sounds like it should be handled in the driver. Is it a simple, 
> constant correlation of ref_clk period to this value?

I don't know. I'll look into it.

Regards,
John