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d46a24a9d2
In mmc_poll_for_busy() we loop continuously, either by sending a CMD13 or by invoking the ->card_busy() host ops, as to detect when the card stops signaling busy. This behaviour is problematic as it may cause CPU hogging, especially when the busy signal time reaches beyond a few ms. Let's fix the issue by adding a throttling mechanism, that inserts a usleep_range() in between the polling attempts. The sleep range starts at 32-64us, but increases for each loop by a factor of 2, up until the range reaches ~32-64ms. In this way, we are able to keep the loop fine-grained enough for short busy signaling times, while also not hogging the CPU for longer times. Note that, this change is inspired by the similar throttling mechanism that we already use for mmc_do_erase(). Reported-by: Michał Mirosław <mirq-linux@rere.qmqm.pl> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Tested-by: Ludovic Barre <ludovic.barre@st.com> Reviewed-by: Ludovic Barre <ludovic.barre@st.com> Link: https://lore.kernel.org/r/20200204085449.32585-2-ulf.hansson@linaro.org |
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