linux-kernel - Re: [PATCH v3] USB: PHY: Re-organize Tegra USB PHY driver

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Date:	Mon, 24 Sep 2012 11:48:05 +0530
From:	"ABRAHAM, KISHON VIJAY" <kishon@...com>
To:	Venu Byravarasu <vbyravarasu@...dia.com>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	"balbi@...com" <balbi@...com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v3] USB: PHY: Re-organize Tegra USB PHY driver

Hi,

On Sat, Sep 22, 2012 at 2:08 PM, Venu Byravarasu <vbyravarasu@...dia.com> wrote:
>> -----Original Message-----
>> From: Stephen Warren [mailto:swarren@...dotorg.org]
>> Sent: Friday, September 21, 2012 9:45 PM
>> To: ABRAHAM, KISHON VIJAY
>> Cc: Venu Byravarasu; balbi@...com; gregkh@...uxfoundation.org; linux-
>> kernel@...r.kernel.org; linux-usb@...r.kernel.org
>> Subject: Re: [PATCH v3] USB: PHY: Re-organize Tegra USB PHY driver
>>
>> On 09/21/2012 07:09 AM, ABRAHAM, KISHON VIJAY wrote:
>> > Hi,
>> >
>> > On Fri, Sep 21, 2012 at 5:50 PM, Venu Byravarasu
>> <vbyravarasu@...dia.com> wrote:
>> >> NVIDIA produces several Tegra SoCs viz Tegra20, Tegra30 etc.
>> >> In order to support USB PHY drivers on these SoCs, existing
>> >> PHY driver is split into SoC agnostic common USB PHY driver
>> >> and Tegra20-specific USB phy driver. This will facilitate
>> >> easy addition and deletion of phy drivers for Tegra SoCs.
>>
>> >> @@ -618,6 +618,9 @@ static int tegra_ehci_probe(struct platform_device
>> *pdev)
>> ...
>> >>         pdata = pdev->dev.platform_data;
>> >>         if (!pdata) {
>>
>> Some missing lines of context are:
>>
>>                 dev_err(&pdev->dev, "Platform data missing\n");
>>                 return -EINVAL;
>>         }
>>
>> ...
>> >> +       params.mode = TEGRA_USB_PHY_MODE_HOST;
>> >> +       params.config = pdata->phy_config;
>> >
>> > I fail to understand how pdata is not NULL in dt boot. I know i've
>> > already given this comment and you replied that you dint see any
>> > crash. But I'd like to know where and how pdata gets populated.
>>
>> In practice, the platform uses AUXDATA to provide platform data to the
>> driver even when it's instantiated using device tree; see
>> arch/arm/mach-tegra/board-dt-tegra20.c variables tegra_ehci*_pdata and
>> tegra20_auxdata_lookup[].
>>
>> In the slightly (very very slightly, hopefully) longer term, I would
>> like to completely remove the AUXDATA setup from board-dt-tegra20.c;
>> tegra_ehci_probe() should do something like:
>>
>> pdata = pdev->dev.platform_data
>> if (!pdata)
>>     pdata = parse_pdata_from_dt();
>> /* user didn't specify any in DT either */
>> if (!pdata)
>>     pdata = default_pdata_for_port();
>>
>> ... where perhaps the use of defaults could be folded into
>> parse_pdata_from_dt().
>
>
> Thanks Stephen for the detailed explanation.
>
> Kishon / Felipe,
> Do you have any more questions in this related, before patch can be applied?

I don't have any further comments.

Thanks
Kishon
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