linux-kernel - Re: [Patch v9 3/3] phy: Add Qualcomm DWC3 HS/SS PHY driver

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Date:	Mon, 15 Sep 2014 12:07:12 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	<balbi@...com>
CC:	Andy Gross <agross@...eaurora.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	Jack Pham <jackp@...eaurora.org>,
	Kumar Gala <galak@...eaurora.org>,
	<linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	"Ivan T. Ivanov" <iivanov@...sol.com>,
	Bjorn Andersson <bjorn.andersson@...ymobile.com>
Subject: Re: [Patch v9 3/3] phy: Add Qualcomm DWC3 HS/SS PHY driver

Hi,

On Sunday 14 September 2014 07:54 AM, Felipe Balbi wrote:
> Hi,
> 
> On Sat, Sep 13, 2014 at 12:16:01PM +0530, Kishon Vijay Abraham I wrote:
>> On Saturday 13 September 2014 12:58 AM, Andy Gross wrote:
>>> This patch adds a new driver for the Qualcomm USB 3.0 PHY that exists on some
>>> Qualcomm platforms.  This driver uses the generic PHY framework and will
>>> interact with the DWC3 controller.
>>
>> Do you have dt documentation for this driver?
> 
> see patch 1

hmm.. missed that.
> 
>>> +static inline void qcom_dwc3_phy_write_readback(
>>> +	struct qcom_dwc3_usb_phy *phy_dwc3, u32 offset,
>>> +	const u32 mask, u32 val)
>>> +{
>>> +	u32 write_val, tmp = readl(phy_dwc3->base + offset);
>>> +
>>> +	tmp &= ~mask;		/* retain other bits */
>>> +	write_val = tmp | val;
>>> +
>>> +	writel(write_val, phy_dwc3->base + offset);
>>> +
>>> +	/* Read back to see if val was written */
>>
>> Does it fail sometime? I'm not sure if this should be present in the
>> driver since this looks more of a debug code.
> 
> this was mentioned before. Silicon bug.

okay.
> 
>>> +	writel_relaxed(data | SSUSB_CTRL_SS_PHY_RESET,
>>> +		phy_dwc3->base + SSUSB_PHY_CTRL_REG);
>>> +	usleep_range(2000, 2200);
>>
>> use msleep here..
> 
> why ? usleep_range() gives the scheduler oportunity to group timers.

Was of the opinion that for larger delays msleep should be used. But looks like
it is only for 10+ ms (Documentation/timers/timers-howto.txt).

Thanks
Kishon
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