[PATCH v3 1/3] usb: dwc3: Support quirk for writing high-low order

[Daehwan Jung]

There's the limitation of Synopsys dwc3 controller with ERST programming in
supporting separate ERSTBA_HI and ERSTBA_LO programming. It's supported when
the ERSTBA is programmed ERSTBA_HI before ERSTBA_LO. But, writing operations
in xHCI is done low-high order following xHCI spec. xHCI specification 5.1
"Register Conventions" states that 64 bit registers should be written in
low-high order. Synopsys dwc3 needs workaround for high-low order. That's why
adding new quirk is needed to support this.

Signed-off-by: Daehwan Jung <dh10.jung@xxxxxxxxxxx>
---
v1 -> v2:
- this patch is added newly in the patchset
- add a property in dwc3 structure
v2 -> v3:
- add change note
- add description in commit message
- remove the property in dwc3 structure to pass it unconditionally
---
 drivers/usb/dwc3/host.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
index a171b27..e0533ce 100644
--- a/drivers/usb/dwc3/host.c
+++ b/drivers/usb/dwc3/host.c
@@ -126,7 +126,7 @@ static int dwc3_host_get_irq(struct dwc3 *dwc)
 
 int dwc3_host_init(struct dwc3 *dwc)
 {
-	struct property_entry	props[5];
+	struct property_entry	props[6];
 	struct platform_device	*xhci;
 	int			ret, irq;
 	int			prop_idx = 0;
@@ -162,6 +162,8 @@ int dwc3_host_init(struct dwc3 *dwc)
 
 	props[prop_idx++] = PROPERTY_ENTRY_BOOL("xhci-sg-trb-cache-size-quirk");
 
+	props[prop_idx++] = PROPERTY_ENTRY_BOOL("write-64-hi-lo-quirk");
+
 	if (dwc->usb3_lpm_capable)
 		props[prop_idx++] = PROPERTY_ENTRY_BOOL("usb3-lpm-capable");
 
-- 
2.7.4