Re: [PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP

Re: [PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP

[Marc Dietich]

> Hi Marc,

^dito,

> On 31/08/11 17:55, Marc Dietrich wrote:
> > Am Mittwoch 31 August 2011, 18:12:48 schrieb Marc Zyngier:
> >> [...]
> >> Oddly enough, this patch doesn't do anything on my Tegra setup. In both
> >> cases, I get around 17MB/s from a crap SD card plugged in a USB reader.
> >> 
> >> This leads me to suspect that this issue is very much OMAP4 specific.
> >> Can anyone verify this theory on other some A9 platforms?
> > 
> > That's odd. On my Tegra2 (on ac100) it boosts the transfer rate from 7 to
> > 17 MB/s.
> 
> I'm using a Harmony board. Could you share your kernel version, .config
> and dmesg?
> 
> Thanks,
> 
> 	M.

I use the chromiumos tree (for chromiumos 2.6.38 kernel: 
http://git.chromium.org/chromiumos/third_party/kernel-next.git) with some 
additions to make it run on the AC100. This modified tree is on 
git://gitorious.org/~marvin24/ac100/marvin24s-kernel.git. The config is 
paz00_defconfig and a dmesg you can get e.g. from http://pastebin.com/9uVfDWma
(it's not very current, but it should be sufficient).

I'll add Stephen Warren from NVIDIA to the CC list. He has more HW to test on. 

Btw, this is the patch I used: http://gitorious.org/~marvin24/ac100/marvin24s-
kernel/commit/cce8d9e25d009a45c219a6ad0b9ac4e27d034ab0

	Marc
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RE: [PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP

[Stephen Warren]

Marc Dietich wrote at Thursday, September 01, 2011 5:14 AM:
> I'll add Stephen Warren from NVIDIA to the CC list. He has more HW to test on.

Here are the results I found:

Harmony:
Tegra USB3 -> SMSC9514 hub: NOT affected
(Unplugging LAN cable, or disabling SMSC9514 LAN driver doesn't change this)

Seaboard (springbank; clamshell):
Tegra USB1 -> no hub: Affected

Seaboard (seaboard non-clamshell):
Tegra USB1 -> no hub: Affected
Tegra USB3 -> no hub: Affected

TrimSlice:
Tegra USB3 -> unknown hub: Affected

This implies there's something different about Harmony.

Is the USB hub a clue? Seaboard doesn't have one, and although I don't
know what model TrimSlice uses, I assume it's different since I know
TrimSlice's Ethernet is not the same as Harmony's.

I don't see anything in board-harmony.c vs. board-seaboard.c that'd affect
anything USB-related.

Perhaps there's some kind of bootloader or BCT difference. However, my
Harmony and both Seaboards both use (a very old) U-Boot and BCT from
ChromeOS, so I don't imagine there's actually much difference there.

-- 
nvpublic

Re: [PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP

[Marc Zyngier]

On 01/09/11 20:08, Stephen Warren wrote:
> Marc Dietich wrote at Thursday, September 01, 2011 5:14 AM:
>> I'll add Stephen Warren from NVIDIA to the CC list. He has more HW to test on.
> 
> Here are the results I found:
> 
> Harmony:
> Tegra USB3 -> SMSC9514 hub: NOT affected
> (Unplugging LAN cable, or disabling SMSC9514 LAN driver doesn't change this)
> 
> Seaboard (springbank; clamshell):
> Tegra USB1 -> no hub: Affected
> 
> Seaboard (seaboard non-clamshell):
> Tegra USB1 -> no hub: Affected
> Tegra USB3 -> no hub: Affected
> 
> TrimSlice:
> Tegra USB3 -> unknown hub: Affected
> 
> This implies there's something different about Harmony.
> 
> Is the USB hub a clue? Seaboard doesn't have one, and although I don't
> know what model TrimSlice uses, I assume it's different since I know
> TrimSlice's Ethernet is not the same as Harmony's.

Panda has the exact same USB hub configuration, and is affected. So we
can rule this out.

> I don't see anything in board-harmony.c vs. board-seaboard.c that'd affect
> anything USB-related.
> 
> Perhaps there's some kind of bootloader or BCT difference. However, my
> Harmony and both Seaboards both use (a very old) U-Boot and BCT from
> ChromeOS, so I don't imagine there's actually much difference there.

I just noticed something else. Harmony is fast *most of the time*. In
about one in 3 reboots, I get the slow behavior. When USB is fast, I
also have I2C interrupts "screaming":

 85:     294321          0       GIC  tegra-i2c
116:          0          0       GIC  tegra-i2c
118:      98542          0       GIC  tps6586x

This is a couple of seconds after boot.

When USB is slow, I see the following:
[    0.385270] tps6586x 3-0034: Chip ID read failed: -121
[    0.390584] tps6586x: probe of 3-0034 failed with error -5

... and I2C interrupt is quiet.

The I2C interrupt handler calls writel(), which does a cache sync. That
would explain the "fast" behavior of Harmony.

Do you see the same this on your board?

	M.
-- 
Jazz is not dead. It just smells funny...

RE: [PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP

[Stephen Warren]

Marc Zyngier wrote at Friday, September 02, 2011 3:51 AM:
> On 01/09/11 20:08, Stephen Warren wrote:
> > Marc Dietich wrote at Thursday, September 01, 2011 5:14 AM:
> >> I'll add Stephen Warren from NVIDIA to the CC list. He has more HW to test on.
> >
> > Here are the results I found:
> >
> > Harmony:
> > Tegra USB3 -> SMSC9514 hub: NOT affected
> > (Unplugging LAN cable, or disabling SMSC9514 LAN driver doesn't change this)
...
> I just noticed something else. Harmony is fast *most of the time*. In
> about one in 3 reboots, I get the slow behavior. When USB is fast, I
> also have I2C interrupts "screaming":
> 
>  85:     294321          0       GIC  tegra-i2c
> 116:          0          0       GIC  tegra-i2c
> 118:      98542          0       GIC  tps6586x
> 
> This is a couple of seconds after boot.
> 
> When USB is slow, I see the following:
> [    0.385270] tps6586x 3-0034: Chip ID read failed: -121
> [    0.390584] tps6586x: probe of 3-0034 failed with error -5
> 
> ... and I2C interrupt is quiet.
> 
> The I2C interrupt handler calls writel(), which does a cache sync. That
> would explain the "fast" behavior of Harmony.
> 
> Do you see the same this on your board?

Yes, I re-ran the test a few more times and see those exact same symptoms.

In a case with the screaming I2C interrupts and fast USB, I then did:

echo 3-0034 > /sys/bus/i2c/drivers/tps6586x/unbind
(I got a kernel BUG and bash crashed here, but just logged back in)

which caused the I2C interrupt handler to stop, then re-ran the test.
I then saw the slow USB speed.

So, now I think *all* platforms(boards) are affected, right?

-- 
nvpublic

Re: [PATCH] usb: ehci: make HC see up-to-date qh/qtd descriptor ASAP

[Marc Dietich]

just another measurement point

> Stephen Warren wrote at Thursday:
>
> Here are the results I found:
> 
> Harmony:
> Tegra USB3 -> SMSC9514 hub: NOT affected
> (Unplugging LAN cable, or disabling SMSC9514 LAN driver doesn't change
> this)
> 
> Seaboard (springbank; clamshell):
> Tegra USB1 -> no hub: Affected
> 
> Seaboard (seaboard non-clamshell):
> Tegra USB1 -> no hub: Affected
> Tegra USB3 -> no hub: Affected
> 
> TrimSlice:
> Tegra USB3 -> unknown hub: Affected

PAZ00:
ULPI -> SMCS 2512: Affected
Tegra USB3 -> SMSC 2514: Affected

The patch also cures high latencies/packet drops on wifi connected to ULPI via 
the 2512 hub. The pen drive was connected to USB3/2514.

> This implies there's something different about Harmony.
> 
> Is the USB hub a clue? Seaboard doesn't have one, and although I don't
> know what model TrimSlice uses, I assume it's different since I know
> TrimSlice's Ethernet is not the same as Harmony's.
> 
> I don't see anything in board-harmony.c vs. board-seaboard.c that'd affect
> anything USB-related.
> 
> Perhaps there's some kind of bootloader or BCT difference. However, my
> Harmony and both Seaboards both use (a very old) U-Boot and BCT from
> ChromeOS, so I don't imagine there's actually much difference there.