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d98995b4bf
The test of write combining was added before in mlx5_ib driver. It opens UD QP and posts NOP WQEs, and uses BlueFlame doorbell. When BlueFlame is used, WQEs get written directly to a PCI BAR of the device (in addition to memory) so that the device handles them without having to access memory. In this test, the WQEs written in memory are different from the ones written to the BlueFlame which request CQE update. By checking the completion reports posted on CQ, we can know if BlueFlame succeeds or not. The write combining must be supported if BlueFlame succeeds as its register is written using write combining. This patch reimplements the test in the same way, but using a pair of SQ and CQ only. It is moved to mlx5_core as a general feature used by both mlx5_core and mlx5_ib. Besides, save write combine test result of the PCI function, so that its thousands of child functions such as SF can query without paying the time and resource penalty by itself. The test function is called only after failing to get the cached result. With this enhancement, all thousands of SFs of the PF attached to same driver no longer need to perform WC check explicitly, which is already done in the system. This saves several commands per SF, thereby speeds up SF creation and also saves completion EQ creation. Signed-off-by: Jianbo Liu <jianbol@nvidia.com> Reviewed-by: Tariq Toukan <tariqt@nvidia.com> Link: https://lore.kernel.org/r/4ff5a8cc4c5b5b0d98397baa45a5019bcdbf096e.1717409369.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org>