mmc: sdhci: Reduce maximum time under spinlock in sdhci_send_command()
Spending time under spinlock increases IRQ latencies and also response times because preemption is disabled. sdhci_send_command() waits up to 10 ms under spinlock for inhibit bits to clear. In general inhibit bits will not be set, but there may be corner cases, especially in the face of errors, where waiting helps. There might also be dysfunctional hardware that needs the waiting. So retain the legacy behaviour but do not wait for inhibit bits while under spinlock. Instead adjust the logic to enable waiting while not under spinlock. That is mostly straight forward, but in the interrupt handler it requires deferring an "inhibited" command to the IRQ thread where sleeping is allowed. Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com> Tested-by: NBaolin Wang <baolin.wang7@gmail.com> Link: https://lore.kernel.org/r/20200412090349.1607-6-adrian.hunter@intel.comSigned-off-by: NUlf Hansson <ulf.hansson@linaro.org>
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