usb: xhci: expand mitigations for VLI_SS_BULK_OUT_BUG quirk #5173
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pelwell
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Sep 13, 2022
The VL805 can cause data corruption if a SS Bulk OUT endpoint enters a flow-control condition and there are TRBs in the transfer ring that are not an integral size of wMaxPacket and the endpoint is behind one or more hubs. This is frequently the case encountered when FAT32 filesystems are present on mass-storage devices with cluster sizes of 1 sector, and the filesystem is being written to with an aggregate of small files. The initial implementation of this quirk separated TRBs that didn't adhere to this limitation into two - the first a multiple of wMaxPacket and the second the 512-byte remainder - in an attempt to force TD fragments to align with packet boundaries. This reduced the incidence rate of data corruption but did not resolve it. The fix as recommended by VIA is to disable bursts if this sequence of TRBs can occur. Limit turning off bursts to just USB mass-storage devices by searching the device's configuration for an interface with a class type of USB_CLASS_MASS_STORAGE. Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
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popcornmix
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popcornmix
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hselasky
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After several months back-and-forth with VIA, we have a candidate root-cause for #4844 and a suggested fix. My known-bad pendrive now gets written to endlessly without suffering data corruption.