Re: [RFC PATCH 1/2] usb: hcd: Remove USB phy if needed

[Felipe Balbi <balbi@ti.com>]

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Hi,

On Wed, Nov 06, 2013 at 08:43:36PM +0400, Valentine wrote:
> On 11/06/2013 07:45 PM, Felipe Balbi wrote:
> >Hi,
> >
> >On Wed, Nov 06, 2013 at 12:33:26AM +0400, Valentine Barshak wrote:
> >>This adds remove_phy flag to the HCD structure. If the flag is
> >>set and if hcd->phy is valid, the phy is shutdown and released
> >>whenever usb_add_hcd fails or usb_hcd_remove is called.
> >>This can be used by the HCD drivers to auto-remove
> >>the external USB phy when it is no longer needed.
> >>
> >>Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
> >>---
> >>  drivers/usb/core/hcd.c  | 14 +++++++++++++-
> >>  include/linux/usb/hcd.h |  1 +
> >>  2 files changed, 14 insertions(+), 1 deletion(-)
> >>
> >>diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
> >>index d6a8d23..d939521 100644
> >>--- a/drivers/usb/core/hcd.c
> >>+++ b/drivers/usb/core/hcd.c
> >>@@ -43,6 +43,7 @@
> >>
> >>  #include <linux/usb.h>
> >>  #include <linux/usb/hcd.h>
> >>+#include <linux/usb/phy.h>
> >>
> >>  #include "usb.h"
> >>
> >>@@ -2611,7 +2612,7 @@ int usb_add_hcd(struct usb_hcd *hcd,
> >>  	 */
> >>  	if ((retval = hcd_buffer_create(hcd)) != 0) {
> >>  		dev_dbg(hcd->self.controller, "pool alloc failed\n");
> >>-		return retval;
> >>+		goto err_remove_phy;
> >>  	}
> >>
> >>  	if ((retval = usb_register_bus(&hcd->self)) < 0)
> >>@@ -2742,6 +2743,12 @@ err_allocate_root_hub:
> >>  	usb_deregister_bus(&hcd->self);
> >>  err_register_bus:
> >>  	hcd_buffer_destroy(hcd);
> >>+err_remove_phy:
> >>+	if (hcd->remove_phy && hcd->phy) {
> >>+		usb_phy_shutdown(hcd->phy);
> >>+		usb_put_phy(hcd->phy);
> >>+		hcd->phy = NULL;
> >>+	}
> >
> >why do you need the flag at all ? If hcd->phy is valid, just casll
> >usb_phy_shutdown() followed by usb_put_phy(). Did you find any issues
> >with that ?
> >
> 
> I haven't been able to test it with other platforms.
> However, some drivers use devm_usb_get_phy_dev() and we may face refcounter issues
> if we call usb_put_phy unconditionally.
> Adding this flag seems safe enough and we doesn't affect other drivers.

then use devm_usb_get_phy_dev() here and remove the call from all other
drivers ;-)

-- 
balbi

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