Re: [PATCH 4/7] phy: meson: add USB2 PHY support for Meson8b and GXBB

On 08/09/16 20:35, Kevin Hilman wrote:

Martin Blumenstingl [off-list ref] writes:

quoted

This is a new driver for the USB PHY found in Meson8b and GXBB SoCs.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
Signed-off-by: Jerome Brunet <jbrunet-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>

I tested this on meson-gxbb-p200 with USB host and a mass storage
device.

Tested-by: Kevin Hilman <khilman-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>

A minor question/comment below, for you and for Kishon...

[...]

quoted

+static int phy_meson_usb2_probe(struct platform_device *pdev)
+{
+	struct phy_meson_usb2_priv *priv;
+	struct resource *res;
+	struct phy *phy;
+	struct phy_provider *phy_provider;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->clk_usb_general = devm_clk_get(&pdev->dev, "usb_general");
+	if (IS_ERR(priv->clk_usb_general))
+		return PTR_ERR(priv->clk_usb_general);
+
+	priv->clk_usb = devm_clk_get(&pdev->dev, "usb");
+	if (IS_ERR(priv->clk_usb))
+		return PTR_ERR(priv->clk_usb);
+
+	priv->dr_mode = of_usb_get_dr_mode_by_phy(pdev->dev.of_node, -1);
+	if (priv->dr_mode == USB_DR_MODE_UNKNOWN) {
+		dev_err(&pdev->dev,
+			"missing dual role configuration of the controller\n");
+		return -EINVAL;
+	}
+
+	phy = devm_phy_create(&pdev->dev, NULL, &phy_meson_usb2_ops);
+	if (IS_ERR(phy)) {
+		dev_err(&pdev->dev, "failed to create PHY\n");
+		return PTR_ERR(phy);
+	}
+
+	if (usb_reset_refcnt++ == 0) {
+		ret = device_reset(&pdev->dev);
+		if (ret) {
+			dev_err(&phy->dev, "Failed to reset USB PHY\n");
+			return ret;
+		}
+	}

The ref count + reset here looks like something that could/should be
handled in a runtime PM callback.

IOW, there should be a pm_runtime_get_sync() here, and in the
->runtime_resume() callback, the device_reset() would be called.
Runtime PM does the refcounting, and only calls ->runtime_resume() on
the 0 -> 1 transition.

This isn't a big deal for now, so I'll let Kishon decide, but using
runtime PM from the start will help enabling other PM features later.

I agree, pm_runtime would probably be the best place to handle >1
device with shared items such as reset.

The version I wrote, I simply enabled the clocks and reset the device
when probed to work around the shared reset.


-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius
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