linux-kernel - Re: [PATCH v1 4/9] pinctrl: tegra-xusb: Add USB PHY support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <53AC61B9.5030408@wwwdotorg.org>
Date:	Thu, 26 Jun 2014 12:08:57 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Andrew Bresticker <abrestic@...omium.org>
CC:	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, linux-usb@...r.kernel.org,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Linus Walleij <linus.walleij@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Grant Likely <grant.likely@...aro.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Kishon Vijay Abraham I <kishon@...com>,
	Arnd Bergmann <arnd@...db.de>, balbi@...com
Subject: Re: [PATCH v1 4/9] pinctrl: tegra-xusb: Add USB PHY support

On 06/25/2014 05:30 PM, Andrew Bresticker wrote:
> On Wed, Jun 25, 2014 at 3:12 PM, Stephen Warren <swarren@...dotorg.org> wrote:
>> On 06/18/2014 12:16 AM, Andrew Bresticker wrote:
>>> In addition to the PCIe and SATA PHYs, the XUSB pad controller also
>>> supports 3 UTMI, 2 HSIC, and 2 USB3 PHYs.  Each USB3 PHY uses a single
>>> PCIe or SATA lane and is mapped to one of the three UTMI ports.
>>>
>>
>>> diff --git a/drivers/pinctrl/pinctrl-tegra-xusb.c b/drivers/pinctrl/pinctrl-tegra-xusb.c
>>
>>> @@ -372,6 +720,193 @@ static int tegra_xusb_padctl_pinconf_group_set(struct pinctrl_dev *pinctrl,
>>>                       padctl_writel(padctl, regval, lane->offset);
>>>                       break;
>>>
>>> +             case TEGRA_XUSB_PADCTL_USB3_PORT_NUM:
>>> +                     if (value >= TEGRA_XUSB_PADCTL_USB3_PORTS) {
>>> +                             dev_err(padctl->dev, "Invalid USB3 port: %lu\n",
>>> +                                     value);
>>> +                             return -EINVAL;
>>> +                     }
>>> +                     if (!is_pcie_sata_lane(group)) {
>>> +                             dev_err(padctl->dev,
>>> +                                     "USB3 port not applicable for pin %d\n",
>>> +                                     group);
>>> +                             return -EINVAL;
>>> +                     }
>>> +                     padctl->usb3_ports[value].lane = group;
>>> +                     break;
>>
>> It feels odd to use pinctrl for a SW-only purpose. In other words, that
>> chunk of code isn't writing the pinconf data to HW, but rather some
>> internal variable.
> 
> Well the mapping of lanes to USB3 ports is a hardware property and we
> do use it when programming the hardware later to choose which set of
> lane registers to program given a USB3 port, but it's true that it's
> not some value we program into HW directly.
> 
>> Perhaps it would make more sense for the DT binding to represent this
>> data directly in a custom property that's parsed at probe() time. That
>> way, pinctrl only touches "real" HW stuff.
> 
> I'm on the fence about this.  If you or others feel strongly about
> this then I can make it a separate DT property and move it out of the
> pinctrl properties.

I'd certainly prefer to use pinctrl bindings only for things that get
directly written into HW. Other configuration data should be easy to
retrieve directly from properties.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/