linux-kernel - Re: [RFC 2/2] usb: dwc3: Add Qualcomm DWC3 glue layer driver

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Date:	Fri, 09 Aug 2013 19:09:18 +0300
From:	"Ivan T. Ivanov" <iivanov@...sol.com>
To:	balbi@...com
Cc:	rob.herring@...xeda.com, pawel.moll@....com, mark.rutland@....com,
	swarren@...dotorg.org, ian.campbell@...rix.com, rob@...dley.net,
	gregkh@...uxfoundation.org, grant.likely@...aro.org,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [RFC 2/2] usb: dwc3: Add Qualcomm DWC3 glue layer driver

Hi, 

On Fri, 2013-08-09 at 16:23 +0300, Felipe Balbi wrote:
> Hi,
> 
> On Tue, Aug 06, 2013 at 02:53:11PM +0300, Ivan T. Ivanov wrote:
> > diff --git a/drivers/usb/dwc3/dwc3-msm.c b/drivers/usb/dwc3/dwc3-msm.c
> > new file mode 100644
> > index 0000000..e509abc
> > --- /dev/null
> > +++ b/drivers/usb/dwc3/dwc3-msm.c
> > @@ -0,0 +1,175 @@
> > +#undef CONFIG_REGULATOR
> 
> why ??????
> 

1. This shows that driver is still not fully tested 
   Regulators support is still missing in the MSM
2. Helps me to load driver successfully. 

> > +static int dwc3_msm_probe(struct platform_device *pdev)
> > +{
> > +	struct device_node *node = pdev->dev.of_node;
> > +	struct dwc3_msm *mdwc;
> > +	struct resource *res;
> > +	void __iomem *tcsr;
> > +	int ret = 0;
> > +
> > +	dev_info(&pdev->dev, "MSM DWC3\n");
> 
> please don't. This is hardly necessary.

Sure, this will be removed.

> 
> > +	mdwc = devm_kzalloc(&pdev->dev, sizeof(*mdwc), GFP_KERNEL);
> > +	if (!mdwc) {
> > +		dev_err(&pdev->dev, "not enough memory\n");
> 
> this message isn't needed either

ok.

> 
> > +	/*
> > +	 * DWC3 Core requires its CORE CLK (aka master / bus clk) to
> > +	 * run at 125Mhz in SSUSB mode and >60MHZ for HSUSB mode.
> > +	 */
> > +	clk_set_rate(mdwc->core_clk, 125000000);
> 
> if this is dwc3's core clock, why don't we teach dwc3.ko about this
> requirement ? Just make sure to have it optional, since x86 and OMAP
> wouldn't need direct fiddling with the clocks.

I have to check whether DWC3 core or Qcom wrapper requires this clock.

> 
> > +	clk_prepare_enable(mdwc->core_clk);
> > +	clk_prepare_enable(mdwc->iface_clk);
> > +	clk_prepare_enable(mdwc->sleep_clk);
> > +	clk_prepare_enable(mdwc->utmi_clk);
> 
> do you really need to enable your clocks here ? Why don't you enable
> them on runtime_resume and disable on runtime_suspend ?

I will like to make it working first and then will improve
power management.

> 
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	tcsr = devm_ioremap_resource(&pdev->dev, res);
> > +	if (!tcsr) {
> > +		dev_dbg(&pdev->dev, "tcsr ioremap failed\n");
> 
> no need to ioremap, also you're likely leaking clocks and regulators
> enabled here.
> 
> Make sure to have something like:
> 
> 	if (!tcsr)
> 		goto err_disable_clocks;
> 
> 	/* TODO This has to be revised */\
> 
> 	[...]
> 

Sure.

> > +	} else {
> > +		/* TODO: This has to be revised */
> > +
> > +		/* Enable USB3 on the primary USB port. */
> > +		writel_relaxed(0x1, tcsr);
> > +		/*
> > +		 * Ensure that TCSR write is completed before
> > +		 * USB registers initialization.
> > +		 */
> > +		mb();
> 
> why don't you use writel() instead. It will add the memory barrier for
> you.

Ok.

Thanks
Ivan


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