[PATCH v1] HSD #18028953892: usb: xhci-dwc3: Fix USB3.1 controller register access in reset state

[Lim, Jit Loon]

> -----Original Message-----
> From: Marek Vasut <marex at denx.de>
> Sent: Thursday, 22 June, 2023 5:35 PM
> To: Lim, Jit Loon <jit.loon.lim at intel.com>; u-boot at lists.denx.de
> Cc: Jagan Teki <jagan at amarulasolutions.com>; Simon
> <simon.k.r.goldschmidt at gmail.com>; Chee, Tien Fong
> <tien.fong.chee at intel.com>; Hea, Kok Kiang <kok.kiang.hea at intel.com>;
> Lokanathan, Raaj <raaj.lokanathan at intel.com>; Maniyam, Dinesh
> <dinesh.maniyam at intel.com>; Ng, Boon Khai <boon.khai.ng at intel.com>;
> Yuslaimi, Alif Zakuan <alif.zakuan.yuslaimi at intel.com>; Chong, Teik Heng
> <teik.heng.chong at intel.com>; Zamri, Muhammad Hazim Izzat
> <muhammad.hazim.izzat.zamri at intel.com>; Tang, Sieu Mun
> <sieu.mun.tang at intel.com>; Bin Meng <bmeng.cn at gmail.com>; Michal Simek
> <monstr at monstr.eu>; Tom Rini <trini at konsulko.com>; Eugen Hristev
> <eugen.hristev at microchip.com>
> Subject: Re: [PATCH v1] HSD #18028953892: usb: xhci-dwc3: Fix USB3.1
> controller register access in reset state
> 
> On 6/22/23 04:48, Lim, Jit Loon wrote:
> >> -----Original Message-----
> >> From: Marek Vasut <marex at denx.de>
> >> Sent: Wednesday, 21 June, 2023 10:19 PM
> >> To: Lim, Jit Loon <jit.loon.lim at intel.com>; u-boot at lists.denx.de
> >> Cc: Jagan Teki <jagan at amarulasolutions.com>; Simon
> >> <simon.k.r.goldschmidt at gmail.com>; Chee, Tien Fong
> >> <tien.fong.chee at intel.com>; Hea, Kok Kiang <kok.kiang.hea at intel.com>;
> >> Lokanathan, Raaj <raaj.lokanathan at intel.com>; Maniyam, Dinesh
> >> <dinesh.maniyam at intel.com>; Ng, Boon Khai <boon.khai.ng at intel.com>;
> >> Yuslaimi, Alif Zakuan <alif.zakuan.yuslaimi at intel.com>; Chong, Teik
> >> Heng <teik.heng.chong at intel.com>; Zamri, Muhammad Hazim Izzat
> >> <muhammad.hazim.izzat.zamri at intel.com>; Tang, Sieu Mun
> >> <sieu.mun.tang at intel.com>; Bin Meng <bmeng.cn at gmail.com>
> >> Subject: Re: [PATCH v1] HSD #18028953892: usb: xhci-dwc3: Fix USB3.1
> >> controller register access in reset state
> >>
> >> On 6/21/23 16:11, Jit Loon Lim wrote:
> >>> From: Teik Heng Chong <teik.heng.chong at intel.com>
> >>>
> >>> The controller registers should not be accessed while the
> >>> controller's vcc_reset_n is asserted.
> >>>
> >>> Signed-off-by: Teik Heng Chong <teik.heng.chong at intel.com>
> >>
> >> Is this patch ported from Linux or is this custom development ?
> >>
> >> Is there a matching patch/fix in Linux already ?
> >
> > In xhci_dwc3_probe(), the program sequence is vcc reset -> clk init ->
> > phy setup -> xhci_register therefore, when xhci_dwc3_remove is called,
> > the proper usb stop sequence should be xhci_register _> phy setup ->
> > clk init -> vcc reset
> >
> > if we look at linux driver
> > https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc3/dwc3-o
> > f-simple.c#L33
> >
> > dwc3_of_simple_probe: The sequence is reset -> clock
> > __dwc3_of_simple_teardown: Then, clock -> reset
> >
> > So based on the above, we have made changes and the uboot fix is now
> aligned with linux driver.
> 
> Instead of adding random patches to the U-Boot dwc3 driver, please just
> synchronize the driver with Linux. You should be able to add the missing
> patches to the DWC3 driver from Linux since the last synchronization point, the
> process should be largely mechanical. Make sure to include commit ID of each
> Linux commit in the new matching U-Boot patch.
> 
> It shouldn't be difficult, one approach I can think of is roughly this:
> - figure out the original merge base from which the DWC3 driver was imported
> to U-Boot
> - in U-Boot, revert all dwc3 patches on top of that import patch
> - pick all Linux kernel dwc3 patches from that merge base and apply on top of
> this U-Boot with reverts
> - Run rebase and drop the reverts, let git drop duplicate patches

We believed the previous reply from us is a bit confusing. 
There is no exact same function/file for U-Boot to use in Linux. 
What we are doing is, we are referring to Linux sequence. 

Linux:  (dwc3_of_simple_probe)
https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc3/dwc3-of-simple.c#L33 
U-Boot: (xhci_dwc3_probe)
https://elixir.bootlin.com/u-boot/latest/source/drivers/usb/host/xhci-dwc3.c#L159 

Linux:  (__dwc3_of_simple_teardown)
https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc3/dwc3-of-simple.c#L98 
U-Boot: (xhci_dwc3_remove)
https://elixir.bootlin.com/u-boot/latest/source/drivers/usb/host/xhci-dwc3.c#L227

So we believed that we can't directly pickup all Linux kernel dwc3 patches and merge to U-Boot.