Commits
Bjørn Mork committed 844e88f0441
net: cdc_mbim: send ZLP only for the specific buggy device Reverting 328d7b8 and instead adding an exception for the Sierra Wireless MC7710. commit 328d7b8 (net: cdc_mbim: send ZLP after max sized NTBs) added a workaround for an issue observed on one specific device. Concerns were raised that this workaround adds a performance penalty to all devices based on questionable, if not buggy, behaviour of a single device: "If you add ZLP for NTBs of dwNtbOutMaxSize, you are heavily affecting CPU load, increasing interrupt load by factor of 2 in high load traffic scenario and possibly decreasing throughput for all other devices which behaves correctly." "The idea of NCM was to avoid extra ZLPs. If your transfer is exactly dwNtbOutMaxSize, it's known, you can submit such request on the receiver side and you do not need any EOT indicatation, so the frametime can be used for useful data." Adding a device specific exception to prevent the workaround from affecting well behaved devices. The assumption here is that needing a ZLP is truly an *exception*. We do not yet have enough data to verify this. The generic workaround in commit 328d7b8 should be considered acceptable despite the performance penalty if the exception list becomes a maintainance hassle. Cc: Alexey ORISHKO <alexey.orishko@stericsson.com> Cc: Yauheni Kaliuta <y.kaliuta@gmail.com> Signed-off-by: Bjørn Mork <bjorn@mork.no> Signed-off-by: David S. Miller <davem@davemloft.net>