linux-kernel - Re: [PATCH v6 3/5] usb: dwc3: add phyif_utmi

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Message-ID: <87d1moi7g7.fsf@linux.intel.com>
Date:	Fri, 08 Jul 2016 16:29:44 +0300
From:	Felipe Balbi <balbi@...nel.org>
To:	Heiko Stuebner <heiko@...ech.de>,
	William Wu <william.wu@...k-chips.com>
Cc:	gregkh@...uxfoundation.org, linux-rockchip@...ts.infradead.org,
	briannorris@...gle.com, dianders@...gle.com,
	kever.yang@...k-chips.com, huangtao@...k-chips.com,
	frank.wang@...k-chips.com, eddie.cai@...k-chips.com,
	John.Youn@...opsys.com, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, sergei.shtylyov@...entembedded.com,
	robh+dt@...nel.org, mark.rutland@....com,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v6 3/5] usb: dwc3: add phyif_utmi_quirk


Hi,

Heiko Stuebner <heiko@...ech.de> 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@...k-chips.com>
>> ---
> [...]
>> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt
>> b/Documentation/devicetree/bindings/usb/dwc3.txt index 020b0e9..8d7317d
>> 100644
>> --- 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.
>
> maybe
> 	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.
>
>
> 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.
>
> 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)
>>  		reg &= ~DWC3_GUSB2PHYCFG_U2_FREECLK_EXISTS;
>> 
>> +	if (dwc->phyif_utmi_quirk) {
>> +		reg &= ~(DWC3_GUSB2PHYCFG_PHYIF_MASK |
>> +		       DWC3_GUSB2PHYCFG_USBTRDTIM_MASK);
>> +		usbtrdtim = dwc->phyif_utmi ? USBTRDTIM_UTMI_16_BIT :
>> +			    USBTRDTIM_UTMI_8_BIT;
>> +		reg |= DWC3_GUSB2PHYCFG_PHYIF(dwc->phyif_utmi) |
>> +		       DWC3_GUSB2PHYCFG_USBTRDTIM(usbtrdtim);
>> +	}
>> +
>>  	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)
>>  				"snps,dis_rxdet_inp3_quirk");
>>  	dwc->dis_u2_freeclk_exists_quirk = device_property_read_bool(dev,
>>  				"snps,dis-u2-freeclk-exists-quirk");
>> +	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 
> that:
>
> 	ret = device_property_read_u8(dev, "snps,phyif-utmi",
> 				 &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

-- 
balbi

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