Re: [PATCH v5 1/3] mfd: Add realtek USB card reader driver

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On 03/26/2014 10:36 PM, Oliver Neukum wrote:
On Tue, 2014-03-25 at 18:44 +0800, rogerable@xxxxxxxxxxx wrote:
From: Roger Tseng <rogerable@xxxxxxxxxxx>


+static int rtsx_usb_probe(struct usb_interface *intf,
+			 const struct usb_device_id *id)
+{
+	struct usb_device *usb_dev = interface_to_usbdev(intf);
+	struct rtsx_ucr *ucr;
+	int ret;
+
+	dev_dbg(&intf->dev,
+		": Realtek USB Card Reader found at bus %03d address %03d\n",
+		 usb_dev->bus->busnum, usb_dev->devnum);
+
+	ucr = devm_kzalloc(&intf->dev, sizeof(*ucr), GFP_KERNEL);
+	if (!ucr)
+		return -ENOMEM;
+
+	ucr->pusb_dev = usb_dev;
+
+	ucr->iobuf = usb_alloc_coherent(ucr->pusb_dev, IOBUF_SIZE,
+			GFP_KERNEL, &ucr->iobuf_dma);
+	if (!ucr->iobuf)
+		return -ENOMEM;
+
+	usb_set_intfdata(intf, ucr);
+
+	ucr->vendor_id = id->idVendor;
+	ucr->product_id = id->idProduct;
+	ucr->cmd_buf = ucr->rsp_buf = ucr->iobuf;
+
+	mutex_init(&ucr->dev_mutex);
+
+	ucr->pusb_intf = intf;
+
+	/* initialize */
+	ret = rtsx_usb_init_chip(ucr);
+	if (ret)
+		goto out_init_fail;
+
+	ret = mfd_add_devices(&intf->dev, usb_dev->devnum, rtsx_usb_cells,
+			ARRAY_SIZE(rtsx_usb_cells), NULL, 0, NULL);

Race condition. What prevents the mfd layer from using this device
before you've finished the next steps of the initialisation?

OK, I'll put the timer init before mfd_add_devices.
+	if (ret)
+		goto out_init_fail;
+
+	/* initialize USB SG transfer timer */
+	init_timer(&ucr->sg_timer);
+	setup_timer(&ucr->sg_timer, rtsx_usb_sg_timed_out, (unsigned long) ucr);
+#ifdef CONFIG_PM
+	intf->needs_remote_wakeup = 1;

Why?
Our reader supports remote wake-up from card slot event(insertion, removal). It should be enabled to let the driver be able to detect the newly inserted card.

+	usb_enable_autosuspend(usb_dev);
+#endif
+
+	return 0;
+
+out_init_fail:
+	usb_free_coherent(ucr->pusb_dev, IOBUF_SIZE, ucr->iobuf,
+			ucr->iobuf_dma);
+	return ret;
+}
+
...
+static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
+{
+	struct rtsx_ucr *ucr =
+		(struct rtsx_ucr *)usb_get_intfdata(intf);
+
+	dev_dbg(&intf->dev, "%s called with pm message 0x%04u\n",
+			__func__, message.event);
+
+	mutex_lock(&ucr->dev_mutex);
+	rtsx_usb_turn_off_led(ucr);

When is this turned on again?


The LED is not in a permanent cut-off state after here. It is called to guarantee the LED is off during suspend to save more power. It could be lit up in the card host drivers(e.g. rtsx_usb_sdmmc.c) anytime whenever necessary.

This has been asked may times. I'm considering putting some comment in next revision.

Best regards,
Roger Tseng
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