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path: root/target/linux/apm821xx/patches-4.14/302-dw-dma-hprot-fix-and-equal-priortiy.patch
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* apm821xx: fix sata access freezesChristian Lamparter2018-07-191-0/+25
The original vendor's driver programmed the dma controller's AHB HPROT values to enable bufferable, privileged mode. This along with the "same priorty for both channels" fixes the freezes according to @takimata, @And.short, that have been reported on the forum by @ticerex. Furtheremore, @takimata reported that the patch also improved the performance of the HDDs considerably: |<https://forum.lede-project.org/t/wd-mybook-live-duo-two-disks/16195/55> |It seems your patch unleashed the full power of the SATA port. |Where I was previously hitting a really hard limit at around |82 MB/s for reading and 27 MB/s for writing, I am now getting this: | |root@OpenWrt:/mnt# time dd if=/dev/zero of=tempfile bs=1M count=1024 |1024+0 records in |1024+0 records out |real 0m 13.65s |user 0m 0.01s |sys 0m 11.89s | |root@OpenWrt:/mnt# time dd if=tempfile of=/dev/null bs=1M count=1024 |1024+0 records in |1024+0 records out |real 0m 8.41s |user 0m 0.01s |sys 0m 4.70s | |This means: 121 MB/s reading and 75 MB/s writing! | |[...] | |The drive is a WD Green WD10EARX taken from an older MBL Single. |I repeated the test a few times with even larger files to rule out |any caching, I'm still seeing the same great performance. OpenWrt is |now completely on par with the original MBL firmware's performance. Signed-off-by: Christian Lamparter <chunkeey@gmail.com>