Re: SMSC9730 Autosuspend/Resume Questions

Hi Nisar,

On 22.10.18 09:03, Nisar.Sayed@microchip.com wrote:

Hi Frieder,

quoted

Hi,

I recently tested a board with SMSC9730 connected via USB HSIC to an
i.MX6S SOC. I used these patches on top of v4.14-rc8 for the USB HSIC
support: [1].

When I turned on autosuspend, the smsc95xx stopped in the middle of the
suspending routine and /sys/bus/usb/devices/usb3/3-
1/power/runtime_status reported "suspending"
forever.

With some debug logs I found out, that the last line of code that was
executed is [2], after that I didn't get any further messages.

Then I applied the following diff and the suspend/resume started to work
reliably:

@@ -1382,10 +1385,11 @@ static int smsc95xx_link_ok_nopm(struct usbnet

*dev)
          ret = smsc95xx_mdio_read_nopm(dev->net, mii->phy_id, MII_BMSR);
          if (ret < 0)
                  return ret;
-
+       /*
          ret = smsc95xx_mdio_read_nopm(dev->net, mii->phy_id, MII_BMSR);
          if (ret < 0)
                  return ret;
+       */

          return !!(ret & BMSR_LSTATUS);
   }

So it seems like the dummy read, that is commented with "first, a dummy
read, needed to latch some MII phys" causes problems in my setup. Do you
have an idea what could be the reason? Is this a proper fix?

  
Link status bit is latch low register and needs to be read twice. You may get wrong Link status with this fix.

Ok, thanks for the information. I guess I'll have to do some more 
debugging to find out why the second read fails in my case.

Frieder