enetc: Workaround for MDIO register access issue
Due to a hardware issue, an access to MDIO registers that is concurrent with other ENETC register accesses may lead to the MDIO access being dropped or corrupted. The workaround introduces locking for all register accesses to the ENETC register space. To reduce performance impact, a readers-writers locking scheme has been implemented. The writer in this case is the MDIO access code (irrelevant whether that MDIO access is a register read or write), and the reader is any access code to non-MDIO ENETC registers. Also, the datapath functions acquire the read lock fewer times and use _hot accessors. All the rest of the code uses the _wa accessors which lock every register access. The commit introducing MDIO support is - commit ebfcb23d ("enetc: Add ENETC PF level external MDIO support") but due to subsequent refactoring this patch is applicable on top of a later commit. Fixes: 6517798d ("enetc: Make MDIO accessors more generic and export to include/linux/fsl") Signed-off-by:Alex Marginean <alexandru.marginean@nxp.com> Signed-off-by:
Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by:
Claudiu Manoil <claudiu.manoil@nxp.com> Link: https://lore.kernel.org/r/20201112182608.26177-1-claudiu.manoil@nxp.com Signed-off-by:
Jakub Kicinski <kuba@kernel.org>
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