Re: Mainlining Linux Sunxi SoC AW USB

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Petr Vorel

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Jul 24, 2021, 9:41:48 AMJul 24
to Greg KH, linu...@vger.kernel.org, linux...@lists.linux.dev, linux...@googlegroups.com
Hi Greg,

[ Cc: linux...@lists.linux.dev and linux...@googlegroups.com, which I
should have done before ]

> On Sat, Jul 24, 2021 at 11:54:40AM +0200, Petr Vorel wrote:
> > Hi,

> > I'd like to cleanup and mainline Linux Sunxi SoC AW USB host driver [1].

> Great!

> > What are the most ugly parts which should be replaced? Loading module does not
> > complain about anything?
> > [267044.912155] awusb: loading out-of-tree module taints kernel.

> That will be fixed by moving it into the tree.

> > [267044.912257] awusb: module verification failed: signature and/or required key missing - tainting kernel

> That shows a mis-match between you building a kernel and what keys were
> used to build the distro kernel you are using.

> > [267044.913399] usbcore: registered new interface driver allwinner
> > [267044.913401] awusb: v0.5:AW USB driver

> Looks fine.
Yep, I meant by this, that I see nothing serious (i.e. agree with you).

> > BTW should it go to the host/Kconfig or misc/Kconfig or elsewhere?

> No idea, is this a host driver or does it control a USB device you plug
> into the system?

> > [1] https://github.com/linux-sunxi/sunxi-livesuite/blob/master/awusb/awusb.c

> I looked at this, and it's a device driver, not a host controller
> driver.

> But it looks to need a userspace program for the ioctls, where is that
> code at? And why does it need any ioctls at all?

> Why is this even a driver at all, it looks like you can write a small
> userspace program using libusb to do everything it does, right? What
> exactly is this driver needed for?

I'm sorry for not providing more info at the beginning. This is a driver for
host computer (i.e. developers laptop) used by LiveSuit tool [2] to flash Images
to the NAND of Allwinner devices. LiveSuit itself [3] is unfortunately provided
only in binary form. The only open source code with GPL v2 license is awusb
driver. Thus I thought I could ease my life with upstreaming at least the
kernel driver. But maybe it's not a good idea. I'm using LiveSuit for flashing
Allwinner A31, but it requires quite old distro due libqtgui4. Maybe sunxi folks
use something newer nowadays, but I haven't found anything in their wiki.

Kind regards,
Petr

[2] https://github.com/linux-sunxi/sunxi-livesuite
[3] https://github.com/linux-sunxi/sunxi-livesuite/tree/master/x86-64

> thanks,

> greg k-h

Greg KH

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Jul 24, 2021, 10:17:43 AMJul 24
to Petr Vorel, linu...@vger.kernel.org, linux...@lists.linux.dev, linux...@googlegroups.com
On Sat, Jul 24, 2021 at 03:41:42PM +0200, Petr Vorel wrote:
> > Why is this even a driver at all, it looks like you can write a small
> > userspace program using libusb to do everything it does, right? What
> > exactly is this driver needed for?
>
> I'm sorry for not providing more info at the beginning. This is a driver for
> host computer (i.e. developers laptop) used by LiveSuit tool [2] to flash Images
> to the NAND of Allwinner devices. LiveSuit itself [3] is unfortunately provided
> only in binary form. The only open source code with GPL v2 license is awusb
> driver. Thus I thought I could ease my life with upstreaming at least the
> kernel driver. But maybe it's not a good idea. I'm using LiveSuit for flashing
> Allwinner A31, but it requires quite old distro due libqtgui4. Maybe sunxi folks
> use something newer nowadays, but I haven't found anything in their wiki.

Ah, that's not going to be good then. Really, this doesn't seem to need
to be a driver at all, and the ioctls are really strange so we would
need to change them anyway before it could be merged. But with no
access to userspace code, that will be quite difficult, so I would push
back on allwinner and have them work on resolving this.

thanks,

greg k-h

Petr Vorel

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Jul 24, 2021, 10:22:22 AMJul 24
to Greg KH, linu...@vger.kernel.org, linux...@lists.linux.dev, linux...@googlegroups.com
Hi Greg,
Understand, it makes sense. Thanks for your time!

@Sunxi community: am I missing something? Using LiveSuit with old distro chroot
and Xephyr with out-of-tree module isn't fun :(.

Kind regards,
Petr

> thanks,

> greg k-h

Christopher Obbard

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Jul 24, 2021, 10:45:25 AMJul 24
to petr....@gmail.com, Greg KH, linu...@vger.kernel.org, linux...@lists.linux.dev, mailing list linux-sunxi
Peter,
Suggest you take a look at sunxi-tools - specifically the sunxi-fel
tool. This is a libusb-based userland tool to talk to these devices.
I'm not sure if it supports flashing to nand on A31 - never tried it -
but have used it to flash to eMMC and SPI flash on their other chips.

hth,
Chris

>
> Kind regards,
> Petr
>
> > thanks,
>
> > greg k-h
>
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Jernej Škrabec

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Jul 24, 2021, 10:54:47 AMJul 24
to Greg KH, Petr Vorel, linu...@vger.kernel.org, linux...@lists.linux.dev, linux...@googlegroups.com
Dne sobota, 24. julij 2021 ob 16:22:16 CEST je Petr Vorel napisal(a):
Community is mostly concerned with mainline kernel nowadays and thus with
standard tools. Few people still use vendor (BSP) kernel and most of those use
it without LiveSuit (like custom distro images).

Now and then people ask about LiveSuit on IRC, but they usually get little
response.

Best regards,
Jernej

Petr Vorel

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Jul 24, 2021, 12:27:59 PMJul 24
to Christopher Obbard, linux...@lists.linux.dev, mailing list linux-sunxi
Hi Chris, all,

[ Dropping Greg and linu...@vger.kernel.org ]
Thanks for a tip. Looking into sources it does not look like sunxi-fel supports
NAND.

Also from Debian wiki [1] (which describes bootable SD Card) it looks like only
old Allwinner u-boot supported access to NAND, thus I'd be surprised if
sunxi-tools supported it. sunxi-bootinfo does not implement NAND,
sunxi-nand-image-builder (which is not built by default) creates raw NAND
images, but now word about flashing.

I wonder why NAND is (probably) not supported by sunxi? Lack of documentation?

Kind regards,
Petr

[1] https://wiki.debian.org/InstallingDebianOn/Allwinner

Petr Vorel

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Jul 24, 2021, 12:34:46 PMJul 24
to Felipe Balbi, linux...@lists.linux.dev, linux...@googlegroups.com
Hi Felipe,

[ Dropping Greg and linu...@vger.kernel.org ]

> Hi,

> Petr Vorel <petr....@gmail.com> writes:
> >> > [1] https://github.com/linux-sunxi/sunxi-livesuite/blob/master/awusb/awusb.c

> >> Why is this even a driver at all, it looks like you can write a small
> >> userspace program using libusb to do everything it does, right? What
> >> exactly is this driver needed for?

> > I'm sorry for not providing more info at the beginning. This is a driver for
> > host computer (i.e. developers laptop) used by LiveSuit tool [2] to flash Images
> > to the NAND of Allwinner devices. LiveSuit itself [3] is unfortunately provided
> > only in binary form. The only open source code with GPL v2 license is awusb
> > driver. Thus I thought I could ease my life with upstreaming at least the
> > kernel driver. But maybe it's not a good idea. I'm using LiveSuit for flashing
> > Allwinner A31, but it requires quite old distro due libqtgui4. Maybe sunxi folks
> > use something newer nowadays, but I haven't found anything in their wiki.

> looks like you could implement that entirely in userspace with libusb ;-)
Thanks for a hint. Yes, whole thing should be able to implement in userspace.
I'll have look if I'm able to reveal what current userspace code (LiveSuit)
does. The goal is to have simple command line tool (no GUI).

Kind regards,
Petr

Petr Vorel

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Jul 24, 2021, 12:46:30 PMJul 24
to Jernej Škrabec, linux...@lists.linux.dev, linux...@googlegroups.com
Hi Jernej,

[ Dropping Greg and linu...@vger.kernel.org ]
Understand. LiveSuit is for me a way back to original firmware.

Kind regards,
Petr

Andre Przywara

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Jul 24, 2021, 1:05:13 PMJul 24
to Petr Vorel, Christopher Obbard, linux...@lists.linux.dev, mailing list linux-sunxi
On Sat, 24 Jul 2021 18:27:53 +0200
Petr Vorel <petr....@gmail.com> wrote:

Hi Petr,
Pure NAND is getting rarer these days, on modern boards we see mostly
eMMC now (maybe SPI NAND). So NAND is only a concern for older SoCs.

There is (limited) NAND support for mainline U-Boot on the C.H.I.P.
boards[1], which use an A13 (derivative). But reliable operation is
only possible with SLC NAND, which means only on the Chip Pro board,
IIUC. Most boards will probably utilise MLC (or worse) NAND these days,
where effects like write and read disturb make operation more
complicated. Maxime has some stories to tell about this.
So it would be first good to know if you have SLC NAND or not.

Because of this direct support for NAND in the tools is understandably
"limited" (as in: non-existent). Except for SPI NOR flash there is no
"direct" flashing support (for eMMC) in the tools anyway, it just relies
on U-Boot support.
How this works is that you use sunxi-fel to upload a (mainline) U-Boot
binary directly into DRAM, and launch that. Then you can use the full
functionality of U-Boot to load your image. Most popular for NAND
support seems to be U-Boot's Android Fastboot implementation over a USB
gadget device, so you can use the off-the-shelf fastboot tool on your
host computer to flash the NAND. Other possibilities would be to use
USB host support or TFTP to first load an image into DRAM, then use
U-Boot commands to write that into the NAND flash.
To my knowledge NAND flash in U-Boot *only* works on the A13/R8/GR8
chips with SLC NAND, and is only enabled and tested on the Chip boards.
Every other combination would require some work; much more work the
farther you move from there (other SoC, MLC, ...).

Cheers,
Andre

[1] https://linux-sunxi.org/NextThingCo_CHIP

Petr Vorel

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Jul 25, 2021, 7:31:10 PMJul 25
to Andre Przywara, Christopher Obbard, linux...@lists.linux.dev, mailing list linux-sunxi
Hi Andre,
I have no idea which type of NAND device has.
It's device based on low end tablet. Can I find this info on running system
(sysfs, /proc, ...). dmesg does not say anything special.

Or is it possible to find it in source code? nand.ko module is some out of tree
code in modules/nand (kernel 3.3):
description: Generic NAND flash driver code
author: nand flash groups

But nothing mentions SLC or MLC. Or do I have to have HW spec?


> Because of this direct support for NAND in the tools is understandably
> "limited" (as in: non-existent). Except for SPI NOR flash there is no
> "direct" flashing support (for eMMC) in the tools anyway, it just relies
> on U-Boot support.
> How this works is that you use sunxi-fel to upload a (mainline) U-Boot
> binary directly into DRAM, and launch that. Then you can use the full
> functionality of U-Boot to load your image. Most popular for NAND
> support seems to be U-Boot's Android Fastboot implementation over a USB
> gadget device, so you can use the off-the-shelf fastboot tool on your
> host computer to flash the NAND. Other possibilities would be to use
> USB host support or TFTP to first load an image into DRAM, then use
> U-Boot commands to write that into the NAND flash.
> To my knowledge NAND flash in U-Boot *only* works on the A13/R8/GR8
> chips with SLC NAND, and is only enabled and tested on the Chip boards.
> Every other combination would require some work; much more work the
> farther you move from there (other SoC, MLC, ...).

Thanks for detailed info. It seems I'll just accept that for mainline my A31
needs sd-card.

Kind regards,
Petr

Maxime Ripard

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Jul 28, 2021, 10:16:51 AMJul 28
to Andre Przywara, Petr Vorel, Christopher Obbard, linux...@lists.linux.dev, mailing list linux-sunxi
Hi,
It works on the A33 as well (the Nintendo board has support for it). And
I guess it works with virtually any SoC, the culprit really is MLC vs
SLC, the NAND controller hasn't really changed.

Maxime
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