From: Marek Vasut <marex@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH v4 2/2] usb: musb: Fix hub port setting for SPLIT transactions
Date: Tue, 22 Dec 2015 01:24:09 +0100 [thread overview]
Message-ID: <201512220124.09583.marex@denx.de> (raw)
In-Reply-To: <1450743664-8612-2-git-send-email-stefan.bruens@rwth-aachen.de>
On Tuesday, December 22, 2015 at 01:21:04 AM, Stefan Br?ns wrote:
> The ifdef'ed Linux kernel code uses the 1 based port number, whereas U-Boot
> puts a 0 based port number into the register. The reason the 0 based port
> number apparently works can probably be taken from the USB 2.0 spec:
>
> 8.4.2.2 Start-Split Transaction Token
> ... The host must correctly set the port field for single and multiple TT
> hub implementations. A single TT hub implementation *may ignore* the port
> field.
>
> Actually, as far as I understand, a multi TT hub defaults to single TT
> (bAlternateSetting: 0) until switched via SetInterface, so even "port 42"
> would work.
>
> The change was verified by hardcoding the port number to a wrong value,
> SPLIT transactions kept working (although using a DWC2 instead of MUSB).
> Tested hubs are the RPi onboard SMC9514 and an external "05e3:0608
> Genesys Logic, Inc. USB-2.0 4-Port HUB". The former is a multi TT hub,
> the latter single TT only.
>
> Addendum: Tested on sunxi/MUSB by Hans de Goede
>
> Signed-off-by: Stefan Br?ns <stefan.bruens@rwth-aachen.de>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> Tested-by: Hans de Goede <hdegoede@redhat.com>
Applied both, thanks!
Best regards,
Marek Vasut
next prev parent reply other threads:[~2015-12-22 0:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-22 0:21 [U-Boot] [PATCH v4 1/2] usb: Move determination of TT hub address/port into separate function Stefan Brüns
2015-12-22 0:21 ` [U-Boot] [PATCH v4 2/2] usb: musb: Fix hub port setting for SPLIT transactions Stefan Brüns
2015-12-22 0:24 ` Marek Vasut [this message]
2015-12-31 15:16 ` [U-Boot] [PATCH v4 1/2] usb: Move determination of TT hub address/port into separate function Marek Vasut
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