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

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Message-ID: <2213342.0Nx5tnEW8p@phil>
Date:	Fri, 08 Jul 2016 14:33:09 +0200
From:	Heiko Stuebner <heiko@...ech.de>
To:	William Wu <william.wu@...k-chips.com>
Cc:	gregkh@...uxfoundation.org, balbi@...nel.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 William,

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;


Heiko