Hi,


On Wed, Jun 25, 2014 at 4:04 AM, Sergei Shtylyov
[off-list ref] wrote:

Hello.


On 06/10/2014 12:22 AM, Julius Werner wrote:

quoted

quoted

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 9ffecd5..453d89e 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h

@@ -1582,6 +1582,9 @@ struct xhci_hcd {
         u32                     port_status_u0;
  /* Compliance Mode Timer Triggered every 2 seconds */
  #define COMP_MODE_RCVRY_MSECS 2000
+       /* phys for the controller */
+       struct phy              *phy2_gen;
+       struct phy              *phy3_gen;
  };

quoted

I don't think adding new variables here and restricting most of this
logic to xhci-plat.c (in the next patch) is the best way to do it.

   Indeed.

quoted

There's no conceptual reason why other host controllers (e.g. xhci-pci
or even EHCI) could not have a similar need to tune their PHY after
reset. PHYs are universal to all host controllers.

quoted

There is already a 'phy' member in struct usb_hcd which I think is
mostly unused right now. I think it would be much less
confusing/redundant to reuse that member for this purpose (you could
still set it up from xhci_plat_probe(), and then call it from
hcd_bus_resume() or something like that).

   That member has type 'struct usb_phy *' while here we have 'struct phy *'
-- feel the difference.
   I have already tried adding 'struct phy *gen_phy' to 'struct usb_hcd',

So the 'struct phy *' available in the usb_hcd is requested in usb_add_hcd().
This is requested with the constant string 'usb' :
           struct phy *phy = phy_get(hcd->self.controller, "usb");

This can get the phy with string 'usb' only if, either the host
controller has a device node wherein the phys are given.
Even in this case one can't give same constant string for two
different phys, UTMI+ and PIPE3 phy, isn't it ?

Or, the other way can be when host gets a lookup table to look into to
find the relevant phys, something like
Heikki has suggested:
usb: dwc3: host: convey the PHYs to xhci
(https://lkml.org/lkml/2014/6/5/585) and related patch series.

So if we use this second approach, we would need to override the
'phy_get()' that has been done in usb_add_hcd()
in xhci_plat_probe(), and then use them in later operations.

am i getting the things correctly ?



-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India