USB PHY documentation

[jbrunet]

On Tue, 2016-08-23 at 14:30 +0100, Ben Dooks wrote:
> On 22/08/2016 22:39, Martin Blumenstingl wrote:
> > 
> > Hello,
> > 
> > last weekend I tried getting the USB PHY working on my GXBB device.
> > The simple part: resetting the USB part and enabling the clocks.
> > The tricky part: configuring the USB PHY registers
> > 
> > Unfortunately the public datasheet does not contain any information
> > about the USB PHY.
> > The reference driver does not contain many comments, the struct
> > members are using abbreviated names and it seems that a part of
> > what
> > should be done by the PHY driver is part of the dwc driver
> > (usb_peri_reg changes were patched into it).
> > I am now wondering if someone can share some details from the 
> > datasheet.
> > 
> > I took my register #defines from the reference driver (and tried to
> > make them human readable): [0]
> > There are some USB_PHY_CLK_SEL_* definitions at the bottom which
> > seem
> > interesting (at least for configuring REG_CONFIG_CLK_SEL, but
> > unfortunately I don't know if these are valid (for either meson8b
> > or
> > gxbb)..
> > 
> > Symptoms are: dwc2's USB initialization is successful, but when I 
> > plug
> > in a device it's not being detected.
> > I *think* that my problem is that REG_ADP_BC_DRV_VBUS is a readonly
> > bit - it's set when I use the original firmware of my device, but I
> > cannot set it in my PHY driver.
> > 
> > In case anyone is interested how my changes look exactly, you can 
> > find
> > the code here: [1]
> > 
> > I also dumped the USB PHY registers from the original Android 
> > firmware
> > of my device in case anyone is interested:
> > phy0:
> > [0xc0000000] = 0x8000
> > [0xc0000004] = 0x1690500
> > [0xc0000008] = 0x0
> > [0xc000000c] = 0x8E18
> > [0xc0000010] = 0x0
> > [0xc0000014] = 0x80000
> > [0xc0000018] = 0x246613D
> > [0xc000001c] = 0x0
> > 
> > phy1:
> > [0xc0000020] = 0x8000
> > [0xc0000024] = 0x1690500
> > [0xc0000028] = 0x0
> > [0xc000002c] = 0x2010118
> > [0xc0000030] = 0x0
> > [0xc0000034] = 0x80000
> > [0xc0000038] = 0xE46613D
> > [0xc000003c] = 0x0
> > 
> > @Ben: did you get anywhere with your experiments on Meson8b (S805)?
> 
> I did a PHY driver and some updates to the dwc2 driver, but could
> not get a reliable USB session going. I'll post my PHY driver later
> as it's still in bits and needs to be made into a semi-coherent patch
> set.
> 
> 
@Martin: I tried your patch and just done a few corrections, mainly
interrupt numbers in the device tree and otg_cap in amlogic_params in
dwc2 driver. the code is here [2]

The host controller seems to be working well on the p200, I'm still
checking the otg controller.

Regards
Jerome

[2]: https://github.com/jeromebrunet/linux/commits/amlogic/v4.8/usb