RE: [PATCH 2/3] phy: renesas: rcar-gen3-usb2: Add support for R7S9210

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>]

Hi Chris-san,

> From: Chris Brandt, Sent: Thursday, November 15, 2018 9:34 PM
> 
> Hi Shimodaさん
> 
> > From: Yoshihiro Shimoda
> > Sent: Thursday, November 15, 2018 4:20 AM
> 
> > > Host does NOT work:
> > > 	//else
> > > 	//	/* No otg, so default to host mode */
> > > 	//	writel(0x00000000, usb2_base + USB2_COMMCTRL);
> >
> > I got it. However, I have a concern how to set the mode to peripheral on
> > RZ/A2
> > if we applied this code. If someone would like to use the USB as
> > peripheral
> > on his board, this code is not suitable.
> 
> But USB peripheral is a different driver. So, this code will not run. So
> USB2_COMMCTRL will keep the default value 0x80000000.
> 
> Correct?

Ah, this is you're correct. R-Car Gen3 code (drivers/usb/renesas_usbhs/rcar3.c) doesn't
have phy control for now.

> > So, I have an idea to set the default mode by using "dr_mode" property,
> > instead of hardcoded. Since the driver already has such a function,
> > we can reuse rcar_gen3_device_recognition() to set the default value.
> > To achieve that, we need to modify the following though.
> >  - Don't enable "is_otg_channel".
> >  - Don't call rcar_gen3_enable_vbus_ctrl() to avoid ADPCTRL register
> >    because RZ/A2 doesn't have it.
> >  - Don't need to call rcar_gen3_set_linectrl to avoid LINECTRL1 register
> >    because RZ/A2 doesn't seem to need the setting on host mode.
> >
> > What do you think?
> 
> If a board is designed for USB peripheral, why would they enable a EHCI
> host driver for the same USB channel?
> I am confused.

I meant that USB peripheral of RZ/A2 need the phy driver, not a EHCI host driver.
And I read Figure 32.1 of the RZ/A2 documentation and I wonder if we need to release
USBCTR.PLL_RST even if we use USB peripheral mode.

# Since the documentations doesn't mention the PHY area exactly, it's confusable for us though.
# But, the phy driver assumed the driver handled "AHB Bridge", "Core" and "UCOM" registers.

> > > > (In other words, if we use the port as peripheral with the reset value
> > > > 0x80000000, does it work?)
> > >
> > > We have not been able to get USB peripheral working on RZ/A2 yet.
> > > For peripheral, RZ/A2 has HS-USB.
> > > After plugging into the PC, HS-USB goes to Suspended state (DVSQ =
> > "0110").
> > > It should go to Configured state (DVSQ = "0011")
> >
> > I guess we need to modify ./drivers/usb/renesas_usbhs/rza.c for RZ/A2
> > because RZ/A2's HS-USB has SYSCFG.CNEN, but doesn't have SYSCFG.UPLLE?
> 
> Today for RZ/A1, we tell people to use USB0 first in their board design,
> then use USB1 if they need a second USB channel. USB pins are dedicated
> (no other function) so there should be no design conflicts.
> 
> If only USB1 is used, USB0 must also be enabled in DT as a dummy driver
> (so SYSCFG.UPLLE can get set for USB1).

Oh, I heard RZ/G1C also has such a hardware register [1].

[1] https://patchwork.kernel.org/patch/10655855/
RZ/G1C channel 0 only has UGCTRL register, but need to set for channel 1.

Best regards,
Yoshihiro Shimoda

> > > According to the RZ/A2 Hardware Manual, COMMCTRL should be 0x80000000
> > when
> > > using HS-USB.
> > >
> > > There are 2 channels of USB on RZ/A2 (host x 2, HS_USB x 2)
> >
> > I got it. So, I guess someone wants to use 1 host and 1 peripheral :)
> 
> Yes.
> 
> Chris