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 <[email protected]> --- ...-dw-dma-hprot-fix-and-equal-priortiy.patch | 25 +++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 target/linux/apm821xx/patches-4.14/302-dw-dma-hprot-fix-and-equal-priortiy.patch diff --git a/target/linux/apm821xx/patches-4.14/302-dw-dma-hprot-fix-and-equal-priortiy.patch b/target/linux/apm821xx/patches-4.14/302-dw-dma-hprot-fix-and-equal-priortiy.patch new file mode 100644 index 0000000000..c6e4331aa9 --- /dev/null +++ b/target/linux/apm821xx/patches-4.14/302-dw-dma-hprot-fix-and-equal-priortiy.patch @@ -0,0 +1,25 @@ +--- a/drivers/dma/dw/core.c ++++ b/drivers/dma/dw/core.c +@@ -167,6 +167,8 @@ static void dwc_initialize_chan_dw(struc + cfghi |= DWC_CFGH_DST_PER(dwc->dws.dst_id); + cfghi |= DWC_CFGH_SRC_PER(dwc->dws.src_id); + ++ cfghi |= DWC_CFGH_PROTCTL(3); /* bufferable + privileged access */ ++ + /* Set polarity of handshake interface */ + cfglo |= hs_polarity ? DWC_CFGL_HS_DST_POL | DWC_CFGL_HS_SRC_POL : 0; + +@@ -1293,11 +1295,8 @@ int dw_dma_probe(struct dw_dma_chip *chi + else + list_add(&dwc->chan.device_node, &dw->dma.channels); + +- /* 7 is highest priority & 0 is lowest. */ +- if (pdata->chan_priority == CHAN_PRIORITY_ASCENDING) +- dwc->priority = pdata->nr_channels - i - 1; +- else +- dwc->priority = i; ++ /* set all channels to the same priority */ ++ dwc->priority = pdata->nr_channels - 1; + + dwc->ch_regs = &__dw_regs(dw)->CHAN[i]; + spin_lock_init(&dwc->lock); -- 2.18.0 _______________________________________________ openwrt-devel mailing list [email protected] https://lists.openwrt.org/mailman/listinfo/openwrt-devel
