On Thu, May 05, 2016 at 10:09:47AM -0400, Alan Stern wrote:

On Thu, 5 May 2016, Krzysztof Kozlowski wrote:

quoted

The autodetection of attached USB device might not work on certain
boards where the power is delivered externally. These devices also might
require a hard reset. Use pwrseq for that in USB hub.

Signed-off-by: Krzysztof Kozlowski <redacted>
---
 drivers/usb/core/hub.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 1c82fcc448f5..0fddaacc62bf 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c

@@ -26,6 +26,7 @@
 #include <linux/mutex.h>
 #include <linux/random.h>
 #include <linux/pm_qos.h>
+#include <linux/pwrseq.h>
 
 #include <asm/uaccess.h>
 #include <asm/byteorder.h>

@@ -1661,7 +1662,17 @@ static int hub_configure(struct usb_hub *hub,
 
 	usb_hub_adjust_deviceremovable(hdev, hub->descriptor);
 
+	/* FIXME: When do the pre-power-on? */

It's hard to answer this without knowing what pre-power-on involves.

In my particular case, I want to achieve a full reset through regulator (off
and on) because the bootloader left it in initialized state. I assume
that if bootloader did not configure the device, the reset won't be
harmful.

In a MMC case, this pre-power-on on is setting the 'reset' GPIO (thus
triggering the reset) and post-power-on is clearing the 'reset'.

Why not create a pwrseq_power_on() routine that does pre_power_on 
followed by post_power_on?

For my purpose it seems sensible.

quoted

+	/*
+	for (i = 0; i < maxchild; i++)
+		pwrseq_pre_power_on(hub->ports[i]->pwrseq);
+	*/
+
+	for (i = 0; i < maxchild; i++)
+		pwrseq_post_power_on(hub->ports[i]->pwrseq);

This is patch 10/13.  hub->ports[i]->pwrseq doesn't get added until 
11/13.  Obviously you never tried compiling each patch in the series.

Ahh yes, I forgot to reorder them. Thanks for spotting this.

quoted

+
 	hub_activate(hub, HUB_INIT);
+

Unnecessary blank line added.

Thanks for feedback,
Krzysztof