From 7b0c03ecc42fb223baf015877fee9d517c2c8af1 Mon Sep 17 00:00:00 2001 From: Christian Lamparter Date: Sat, 17 Nov 2018 17:17:21 +0100 Subject: dmaengine: dw-dmac: implement dma protection control setting This patch adds a new device-tree property that allows to specify the dma protection control bits for the all of the DMA controller's channel uniformly. Setting the "correct" bits can have a huge impact on the PPC460EX and APM82181 that use this DMA engine in combination with a DesignWare' SATA-II core (sata_dwc_460ex driver). In the OpenWrt Forum, the user takimata reported that: |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. Another user And.short reported: |I can report that your fix worked! Boots up fine with two |drives even with more partitions, and no more reboot on |concurrent disk access! A closer look into the sata_dwc_460ex code revealed that the driver did initally set the correct protection control bits. However, this feature was lost when the sata_dwc_460ex driver was converted to the generic DMA driver framework. BugLink: https://forum.openwrt.org/t/wd-mybook-live-duo-two-disks/16195/55 BugLink: https://forum.openwrt.org/t/wd-mybook-live-duo-two-disks/16195/50 Fixes: 8b3444852a2b ("sata_dwc_460ex: move to generic DMA driver") Reviewed-by: Andy Shevchenko Signed-off-by: Christian Lamparter Signed-off-by: Vinod Koul --- include/linux/platform_data/dma-dw.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include') diff --git a/include/linux/platform_data/dma-dw.h b/include/linux/platform_data/dma-dw.h index 896cb71a382c..1a1d58ebffbf 100644 --- a/include/linux/platform_data/dma-dw.h +++ b/include/linux/platform_data/dma-dw.h @@ -49,6 +49,7 @@ struct dw_dma_slave { * @data_width: Maximum data width supported by hardware per AHB master * (in bytes, power of 2) * @multi_block: Multi block transfers supported by hardware per channel. + * @protctl: Protection control signals setting per channel. */ struct dw_dma_platform_data { unsigned int nr_channels; @@ -65,6 +66,11 @@ struct dw_dma_platform_data { unsigned char nr_masters; unsigned char data_width[DW_DMA_MAX_NR_MASTERS]; unsigned char multi_block[DW_DMA_MAX_NR_CHANNELS]; +#define CHAN_PROTCTL_PRIVILEGED BIT(0) +#define CHAN_PROTCTL_BUFFERABLE BIT(1) +#define CHAN_PROTCTL_CACHEABLE BIT(2) +#define CHAN_PROTCTL_MASK GENMASK(2, 0) + unsigned char protctl; }; #endif /* _PLATFORM_DATA_DMA_DW_H */ -- cgit v1.2.3