[RFC v2 10/13] usb: hub: Power sequence the ports on activation

Alan Stern
2016-05-05T14:09:47Z

On Thu, 5 May 2016, Krzysztof Kozlowski wrote:

> 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 <k.kozlowski@samsung.com>
> ---
> 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.

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

> + /*
> + 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.

> +
> hub_activate(hub, HUB_INIT);
> +

Unnecessary blank line added.

> return 0;
>
> fail:

Alan Stern