[PATCH v4 1/2] dt-bindings: dmaengine: dw-dmac: add protection control property

[PATCH v4 1/2] dt-bindings: dmaengine: dw-dmac: add protection control property

[Christian Lamparter]

This patch for the DesignWare AHB Central
Direct Memory Access Controller adds the dma
protection control property:
	"snps,dma-protection-control"

as well as the properties specific values defines into
a new include file: include/dt-bindings/dma/dw-dmac.h

Note: The protection control signals are one-to-one
mapped to the AHB HPROT[1:3] signals for this controller.
The HPROT0 (Data Access) is always hardwired to 1.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
---
---
 Documentation/devicetree/bindings/dma/snps-dma.txt |  4 ++++
 MAINTAINERS                                        |  4 +++-
 include/dt-bindings/dma/dw-dmac.h                  | 14 ++++++++++++++
 3 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 include/dt-bindings/dma/dw-dmac.h

diff --git a/Documentation/devicetree/bindings/dma/snps-dma.txt b/Documentation/devicetree/bindings/dma/snps-dma.txt
index 39e2b26be344..db757df7057d 100644
--- a/Documentation/devicetree/bindings/dma/snps-dma.txt
+++ b/Documentation/devicetree/bindings/dma/snps-dma.txt
@@ -27,6 +27,10 @@ Optional properties:
   general purpose DMA channel allocator. False if not passed.
 - multi-block: Multi block transfers supported by hardware. Array property with
   one cell per channel. 0: not supported, 1 (default): supported.
+- snps,dma-protection-control: AHB HPROT[3:1] protection setting.
+  The default value is 0 (for non-cacheable, non-buffered,
+  unprivileged data access).
+  Refer to include/dt-bindings/dma/dw-dmac.h for possible values.
 
 Example:
 
diff --git a/MAINTAINERS b/MAINTAINERS
index 3bd775ba51ce..68327503fa94 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14379,9 +14379,11 @@ SYNOPSYS DESIGNWARE DMAC DRIVER
 M:	Viresh Kumar <vireshk@kernel.org>
 R:	Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 S:	Maintained
+F:	Documentation/devicetree/bindings/dma/snps-dma.txt
+F:	drivers/dma/dw/
+F:	include/dt-bindings/dma/dw-dmac.h
 F:	include/linux/dma/dw.h
 F:	include/linux/platform_data/dma-dw.h
-F:	drivers/dma/dw/
 
 SYNOPSYS DESIGNWARE ENTERPRISE ETHERNET DRIVER
 M:	Jose Abreu <Jose.Abreu@synopsys.com>
diff --git a/include/dt-bindings/dma/dw-dmac.h b/include/dt-bindings/dma/dw-dmac.h
new file mode 100644
index 000000000000..d1ca705c95b3
--- /dev/null
+++ b/include/dt-bindings/dma/dw-dmac.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
+
+#ifndef __DT_BINDINGS_DMA_DW_DMAC_H__
+#define __DT_BINDINGS_DMA_DW_DMAC_H__
+
+/*
+ * Protection Control bits provide protection against illegal transactions.
+ * The protection bits[0:2] are one-to-one mapped to AHB HPROT[3:1] signals.
+ */
+#define DW_DMAC_HPROT1_PRIVILEGED_MODE	(1 << 0)	/* Privileged Mode */
+#define DW_DMAC_HPROT2_BUFFERABLE	(1 << 1)	/* DMA is bufferable */
+#define DW_DMAC_HPROT3_CACHEABLE	(1 << 2)	/* DMA is cacheable */
+
+#endif /* __DT_BINDINGS_DMA_DW_DMAC_H__ */
-- 
2.19.1

[PATCH v4 2/2] dmaengine: dw-dmac: implement dma protection control setting

[Christian Lamparter]

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 <andriy.shevchenko@linux.intel.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
---
I've included the "LGTM" from Andy from the v2 series and transformed
it into a reviewed-by tag.
---
 drivers/dma/dw/core.c                | 2 ++
 drivers/dma/dw/platform.c            | 6 ++++++
 drivers/dma/dw/regs.h                | 4 ++++
 include/linux/platform_data/dma-dw.h | 6 ++++++
 4 files changed, 18 insertions(+)

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index d0c3e50b39fb..2c5ca1961256 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -160,12 +160,14 @@ static void dwc_initialize_chan_idma32(struct dw_dma_chan *dwc)
 
 static void dwc_initialize_chan_dw(struct dw_dma_chan *dwc)
 {
+	struct dw_dma *dw = to_dw_dma(dwc->chan.device);
 	u32 cfghi = DWC_CFGH_FIFO_MODE;
 	u32 cfglo = DWC_CFGL_CH_PRIOR(dwc->priority);
 	bool hs_polarity = dwc->dws.hs_polarity;
 
 	cfghi |= DWC_CFGH_DST_PER(dwc->dws.dst_id);
 	cfghi |= DWC_CFGH_SRC_PER(dwc->dws.src_id);
+	cfghi |= DWC_CFGH_PROTCTL(dw->pdata->protctl);
 
 	/* Set polarity of handshake interface */
 	cfglo |= hs_polarity ? DWC_CFGL_HS_DST_POL | DWC_CFGL_HS_SRC_POL : 0;
diff --git a/drivers/dma/dw/platform.c b/drivers/dma/dw/platform.c
index f01b2c173fa6..31ff8113c3de 100644
--- a/drivers/dma/dw/platform.c
+++ b/drivers/dma/dw/platform.c
@@ -162,6 +162,12 @@ dw_dma_parse_dt(struct platform_device *pdev)
 			pdata->multi_block[tmp] = 1;
 	}
 
+	if (!of_property_read_u32(np, "snps,dma-protection-control", &tmp)) {
+		if (tmp > CHAN_PROTCTL_MASK)
+			return NULL;
+		pdata->protctl = tmp;
+	}
+
 	return pdata;
 }
 #else
diff --git a/drivers/dma/dw/regs.h b/drivers/dma/dw/regs.h
index 09e7dfdbb790..646c9c960c07 100644
--- a/drivers/dma/dw/regs.h
+++ b/drivers/dma/dw/regs.h
@@ -200,6 +200,10 @@ enum dw_dma_msize {
 #define DWC_CFGH_FCMODE		(1 << 0)
 #define DWC_CFGH_FIFO_MODE	(1 << 1)
 #define DWC_CFGH_PROTCTL(x)	((x) << 2)
+#define DWC_CFGH_PROTCTL_DATA	(0 << 2)	/* data access - always set */
+#define DWC_CFGH_PROTCTL_PRIV	(1 << 2)	/* privileged -> AHB HPROT[1] */
+#define DWC_CFGH_PROTCTL_BUFFER	(2 << 2)	/* bufferable -> AHB HPROT[2] */
+#define DWC_CFGH_PROTCTL_CACHE	(4 << 2)	/* cacheable  -> AHB HPROT[3] */
 #define DWC_CFGH_DS_UPD_EN	(1 << 5)
 #define DWC_CFGH_SS_UPD_EN	(1 << 6)
 #define DWC_CFGH_SRC_PER(x)	((x) << 7)
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 */
-- 
2.19.1

Re: [PATCH v4 1/2] dt-bindings: dmaengine: dw-dmac: add protection control property

[Vinod Koul]

On 17-11-18, 17:17, Christian Lamparter wrote:
> This patch for the DesignWare AHB Central
> Direct Memory Access Controller adds the dma
> protection control property:
> 	"snps,dma-protection-control"
> 
> as well as the properties specific values defines into
> a new include file: include/dt-bindings/dma/dw-dmac.h
> 
> Note: The protection control signals are one-to-one
> mapped to the AHB HPROT[1:3] signals for this controller.
> The HPROT0 (Data Access) is always hardwired to 1.

Applied this series, thanks.

-- 
~Vinod