Re: [PATCH 1/4] usb: usbtmc: handle undersized high-speed bulk IN packets

[sashiko-bot@kernel.org]

> The Siglent SDM4065A-SC advertises 64-byte bulk endpoints at high
> speed. USB 2.0 requires 512 bytes there, and xHCI uses 512. The device
> still sends 64-byte packets, so each packet ends the transfer and
> usbtmc_read() returns only the first one. The rest is read as the next
> reply:
> 
>   usbtmc 1-1.3:1.0: Device sent too small first packet: 8 < 12
>   usbtmc 1-1.3:1.0: Device sent reply with wrong bTag: 4 != 6
> 
> Read one packet per URB in usbtmc_read() on this device. Also check for
> a full first transfer before stripping the alignment bytes, otherwise a
> reply whose padding fills that transfer leaves its trailing ZLP behind.
> The existing 4096-byte path had the same problem.
> 
> Fixes: d7604ff0dc01 ("usb: usbtmc: Optimize usbtmc_read")
> Cc: stable@vger.kernel.org
> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261020-fix-usbtmc-short-packets-v1-0-903f4d029193@tipi-net.de?part=1