Thread (39 messages) 39 messages, 6 authors, 2014-07-10

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

From: Felipe Balbi <hidden>
Date: 2014-06-27 15:01:38
Also in: linux-arm-kernel, linux-tegra, lkml

On Wed, Jun 25, 2014 at 04:30:48PM -0700, Andrew Bresticker wrote:
quoted
quoted
+static int usb3_phy_power_on(struct phy *phy)
+{
+     struct tegra_xusb_padctl *padctl = phy_get_drvdata(phy);
+     int port = usb3_phy_to_port(phy);
+     int lane = padctl->usb3_ports[port].lane;
+     u32 value, offset;
+
+     value = padctl_readl(padctl, XUSB_PADCTL_IOPHY_USB3_PADX_CTL2(port));
+     value &= ~((XUSB_PADCTL_IOPHY_USB3_PAD_CTL2_RX_WANDER_MASK <<
+                 XUSB_PADCTL_IOPHY_USB3_PAD_CTL2_RX_WANDER_SHIFT) |
+                (XUSB_PADCTL_IOPHY_USB3_PAD_CTL2_RX_EQ_MASK <<
+                 XUSB_PADCTL_IOPHY_USB3_PAD_CTL2_RX_EQ_SHIFT) |
+                (XUSB_PADCTL_IOPHY_USB3_PAD_CTL2_CDR_CNTL_MASK <<
+                 XUSB_PADCTL_IOPHY_USB3_PAD_CTL2_CDR_CNTL_SHIFT));
Hmm. So there is a lot of "PHY" stuff here after all.

However, the PHYs implemented here appear to implement very low-level
I/O pad code, whereas the PHYs we have for our USB 2.0 controller are
somewhat higher-level; they're more USB-oriented than just IO pad
oriented. Do you know which level of abstraction a Linux PHY object is
supposed to be? I could never get an answer when I asked before.
The only other PHY driver I've worked with (Exynos USB2/3 PHYs) also
mainly only did low-level pad control stuff, but looking at a couple
of other USB PHYs (MSM, MV), there appear to be others that have
higher-level USB stuff in the PHY driver.  Perhaps Kishon or Felipe
could offer us some guidance?
well, if you're adding a new driver, I'd rather see folks moving over to
the generic phy framework (drivers/phy) because we're trying really hard
to get rid of drivers/usb/phy/. And I think, in your case, it's actually
ok to use pinctrl because you actually are muxing pads to the USB3 PHY,
you just do it lazyly.

my 2 cents

-- 
balbi

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