Changes in V4:
- Removed struct dwc3* as an argument for dwc3_gadget_resize_tx_fifos()
- Removed WARN_ON(1) in case we run out of fifo space
Changes in V3:
- Removed "Reviewed-by" tags
- Renamed series back to RFC
- Modified logic to ensure that fifo_size is reset if we pass the minimum
threshold. Tested with binding multiple FDs requesting 6 FIFOs.
Changes in V2:
- Modified TXFIFO resizing logic to ensure that each EP is reserved a
FIFO.
- Removed dev_dbg() prints and fixed typos from patches
- Added some more description on the dt-bindings commit message
Currently, there is no functionality to allow for resizing the TXFIFOs, and
relying on the HW default setting for the TXFIFO depth. In most cases, the
HW default is probably sufficient, but for USB compositions that contain
multiple functions that require EP bursting, the default settings
might not be enough. Also to note, the current SW will assign an EP to a
function driver w/o checking to see if the TXFIFO size for that particular
EP is large enough. (this is a problem if there are multiple HW defined
values for the TXFIFO size)
It is mentioned in the SNPS databook that a minimum of TX FIFO depth = 3
is required for an EP that supports bursting. Otherwise, there may be
frequent occurences of bursts ending. For high bandwidth functions,
such as data tethering (protocols that support data aggregation), mass
storage, and media transfer protocol (over FFS), the bMaxBurst value can be
large, and a bigger TXFIFO depth may prove to be beneficial in terms of USB
throughput. (which can be associated to system access latency, etc...) It
allows for a more consistent burst of traffic, w/o any interruptions, as
data is readily available in the FIFO.
With testing done using the mass storage function driver, the results show
that with a larger TXFIFO depth, the bandwidth increased significantly.
Test Parameters:
- Platform: Qualcomm SM8150
- bMaxBurst = 6
- USB req size = 256kB
- Num of USB reqs = 16
- USB Speed = Super-Speed
- Function Driver: Mass Storage (w/ ramdisk)
- Test Application: CrystalDiskMark
Results:
TXFIFO Depth = 3 max packets
Test Case | Data Size | AVG tput (in MB/s)
-------------------------------------------
Sequential|1 GB x |
Read |9 loops | 193.60
| | 195.86
| | 184.77
| | 193.60
-------------------------------------------
TXFIFO Depth = 6 max packets
Test Case | Data Size | AVG tput (in MB/s)
-------------------------------------------
Sequential|1 GB x |
Read |9 loops | 287.35
| | 304.94
| | 289.64
| | 293.61
-------------------------------------------
Wesley Cheng (3):
usb: dwc3: Resize TX FIFOs to meet EP bursting requirements
arm64: boot: dts: qcom: sm8150: Enable dynamic TX FIFO resize logic
dt-bindings: usb: dwc3: Add entry for tx-fifo-resize
.../devicetree/bindings/usb/dwc3.txt | 2 +-
arch/arm64/boot/dts/qcom/sm8150.dtsi | 1 +
drivers/usb/dwc3/core.c | 2 +
drivers/usb/dwc3/core.h | 8 ++
drivers/usb/dwc3/ep0.c | 37 +++++-
drivers/usb/dwc3/gadget.c | 115 ++++++++++++++++++
6 files changed, 163 insertions(+), 2 deletions(-)
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
Re-introduce the comment for the tx-fifo-resize setting for the DWC3
controller. This allows for vendors to control if they require the TX FIFO
resizing logic on their HW, as the default FIFO size configurations may
already be sufficient.
Signed-off-by: Wesley Cheng <[email protected]>
Acked-by: Rob Herring <[email protected]>
---
Documentation/devicetree/bindings/usb/dwc3.txt | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
index 9946ff9ba735..489f5da83744 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -105,7 +105,7 @@ Optional properties:
1-16 (DWC_usb31 programming guide section 1.2.3) to
enable periodic ESS TX threshold.
- - <DEPRECATED> tx-fifo-resize: determines if the FIFO *has* to be reallocated.
+ - tx-fifo-resize: determines if the FIFO *has* to be reallocated.
- snps,incr-burst-type-adjustment: Value for INCR burst type of GSBUSCFG0
register, undefined length INCR burst type enable and INCRx type.
When just one value, which means INCRX burst mode enabled. When
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
Enable the flexible TX FIFO resize logic on SM8150. Using a larger TX FIFO
SZ can help account for situations when system latency is greater than the
USB bus transmission latency.
Signed-off-by: Wesley Cheng <[email protected]>
---
arch/arm64/boot/dts/qcom/sm8150.dtsi | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/boot/dts/qcom/sm8150.dtsi b/arch/arm64/boot/dts/qcom/sm8150.dtsi
index a36512d1f6a1..c28523313955 100644
--- a/arch/arm64/boot/dts/qcom/sm8150.dtsi
+++ b/arch/arm64/boot/dts/qcom/sm8150.dtsi
@@ -708,6 +708,7 @@ usb_1_dwc3: dwc3@a600000 {
interrupts = <GIC_SPI 133 IRQ_TYPE_LEVEL_HIGH>;
snps,dis_u2_susphy_quirk;
snps,dis_enblslpm_quirk;
+ tx-fifo-resize;
phys = <&usb_1_hsphy>, <&usb_1_ssphy>;
phy-names = "usb2-phy", "usb3-phy";
};
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project