Re: [PATCH v6 3/5] usb: dwc3: add phyif_utmi_quirk

From: William.wu
Date: Fri Jul 08 2016 - 23:42:04 EST

Dear Heiko & Balbiï

On 2016/7/8 21:29, Felipe Balbi wrote:

Heiko Stuebner <heiko@xxxxxxxxx> writes:
Am Donnerstag, 7. Juli 2016, 10:54:24 schrieb William Wu:
Add a quirk to configure the core to support the
UTMI+ PHY with an 8- or 16-bit interface. UTMI+ PHY
interface is hardware property, and it's platform
dependent. Normall, the PHYIf can be configured
during coreconsultant. But for some specific usb
cores(e.g. rk3399 soc dwc3), the default PHYIf
configuration value is fault, so we need to
reconfigure it by software.

And refer to the dwc3 databook, the GUSB2PHYCFG.USBTRDTIM
must be set to the corresponding value according to
the UTMI+ PHY interface.

Signed-off-by: William Wu <william.wu@xxxxxxxxxxxxxx>
diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt
b/Documentation/devicetree/bindings/usb/dwc3.txt index 020b0e9..8d7317d
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -42,6 +42,10 @@ Optional properties:
- snps,dis-u2-freeclk-exists-quirk: when set, clear the
u2_freeclk_exists in GUSB2PHYCFG, specify that USB2 PHY doesn't provide
a free-running PHY clock.
+ - snps,phyif-utmi-quirk: when set core will set phyif UTMI+ interface.
+ - snps,phyif-utmi: the value to configure the core to support a UTMI+
PHY + with an 8- or 16-bit interface. Value 0 select 8-bit
+ interface, value 1 select 16-bit interface.
snps,phyif-utmi-width = <8> or <16>;

devicetree is about describing the hardware, not the things that get written
to registers :-) . The conversion from the described width to the register
value can easily be done in the driver.
Thanks for your suggestion:-)
Yesï âsnps,phyif-utmi-width = <8> or <16>â is much clearer and easier to understand.
And I have considered the same dts property for phyif-utmi, but I have no good idea about
the conversion from described width to the registers value for the time being.

About phyif utmi width configurationï we need to set two places in GUSB2PHYCFG registerï
according to DWC3 USB3.0 controller databook version3.00aï6.3.46 GUSB2PHYCFG

Bits | Name | Description
13:10 | USBTRDTIM | Sets the turnaround time in PHY clocks.
| | 4'h5: When the MAC interface is 16-bit UTMI+
| | 4'h9: When the MAC interface is 8-bit UTMI+/ULPI.
3 | PHYIF | If UTMI+ is selected, the application uses this bit to configure
| | core to support a UTMI+ PHY with an 8- or 16-bit interface.
| | 1'b0: 8 bits
| | 1'b1: 16 bits

And I think maybe I can try to do this:
change it in dts:
snps,phyif-utmi-width = <8> or <16>;

Then convert to register value like thisï
device_property_read_u8(dev, "snps,phyif-utmi-width",

dwc->phyif_utmi = phyif_utmi_width >> 4;

Ater the conversionï dwc->phyif_utmi value 0 means 8 bits, value 1 means 16 bits,
and it's easier for us to config GUSB2PHYCFG.

Is it OK?

Also I don't think you need two properties for this. If the snps,phyif-utmi
property is specified it indicates that you want to manually set the width
and if it is absent you want to use the IC default. All functions reading
property-values indicate if the property is missing.
Ah, it seems very good to me. One dts property "snps,phyif-utmi" can help to
reconfig phyif utmi width. And it seems that Felipe likes it very much too. :-D
But it looks like there is already a precendence in
snps,tx_de_emphasis(_quirk), so maybe Felipe has a different opinion here?

- snps,is-utmi-l1-suspend: true when DWC3 asserts output signal
utmi_l1_suspend_n, false when asserts utmi_sleep_n
- snps,hird-threshold: HIRD threshold
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 0b7bfd2..94036b1 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -408,6 +408,7 @@ static void dwc3_cache_hwparams(struct dwc3 *dwc)
static int dwc3_phy_setup(struct dwc3 *dwc)
u32 reg;
+ u32 usbtrdtim;
int ret;

reg = dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0));
@@ -503,6 +504,15 @@ static int dwc3_phy_setup(struct dwc3 *dwc)
if (dwc->dis_u2_freeclk_exists_quirk)

+ if (dwc->phyif_utmi_quirk) {
+ usbtrdtim = dwc->phyif_utmi ? USBTRDTIM_UTMI_16_BIT :
+ reg |= DWC3_GUSB2PHYCFG_PHYIF(dwc->phyif_utmi) |
+ }
dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);

return 0;
@@ -834,6 +844,7 @@ static int dwc3_probe(struct platform_device *pdev)
struct resource *res;
struct dwc3 *dwc;
u8 lpm_nyet_threshold;
+ u8 phyif_utmi;
u8 tx_de_emphasis;
u8 hird_threshold;

@@ -880,6 +891,9 @@ static int dwc3_probe(struct platform_device *pdev)
/* default to highest possible threshold */
lpm_nyet_threshold = 0xff;

+ /* default to UTMI+ 8-bit interface */
+ phyif_utmi = 0;
/* default to -3.5dB de-emphasis */
tx_de_emphasis = 1;

@@ -929,6 +943,10 @@ static int dwc3_probe(struct platform_device *pdev)
dwc->dis_u2_freeclk_exists_quirk = device_property_read_bool(dev,
+ dwc->phyif_utmi_quirk = device_property_read_bool(dev,
+ "snps,phyif-utmi-quirk");
+ device_property_read_u8(dev, "snps,phyif-utmi",
+ &phyif_utmi);

As described above device_property_read_u8 will return an error if the
property is not present, so you could fill your dwc->phyif_utmi_quirk from

ret = device_property_read_u8(dev, "snps,phyif-utmi",
dwc->phyif_utmi_quirk = (ret == 0) ? true : false;
I like this much better :-) Unfortunately can't fix tx_deemphasis due to
backwards compatibility :-s
I'll try to follow Heiko's suggestion and fix the dwc->phyif_utmi_quirk next patch.

Best regards,