Messages in this thread | | | Date | Thu, 2 Mar 2023 16:02:26 +0100 | Subject | Re: [RFC PATCH] mmc: core: Disable REQ_FUA if the eMMC supports an internal cache | From | Bean Huo <> |
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On 02.03.23 3:43 PM, Ulf Hansson wrote: > REQ_FUA is in general supported for eMMC cards, which translates into so > called "reliable writes". To support these write operations, the CMD23 > (MMC_CAP_CMD23), needs to be supported by the mmc host too, which is common > but not always the case. > > For some eMMC devices, it has been reported that reliable writes are quite > costly, leading to performance degradations. > > In a way to improve the situation, let's avoid announcing REQ_FUA support > if the eMMC supports an internal cache, as that allows us to rely solely on > flush-requests (REQ_OP_FLUSH) instead, which seems to be a lot cheaper. > Note that, those mmc hosts that lacks CMD23 support are already using this > type of configuration, whatever that could mean. > > Reported-by: Wenchao Chen<wenchao.chen666@gmail.com> > Signed-off-by: Ulf Hansson<ulf.hansson@linaro.org> Acked-by: Bean Huo <beanhuo@micron.com>
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