* SMSC9730 Autosuspend/Resume Questions
@ 2018-10-17 15:21 Frieder Schrempf
2018-10-22 7:03 ` Nisar.Sayed
0 siblings, 1 reply; 3+ messages in thread
From: Frieder Schrempf @ 2018-10-17 15:21 UTC (permalink / raw)
To: Steve Glendinning, Microchip Linux Driver Support,
David S. Miller, netdev
Cc: Oliver Neukum, linux-usb, linux-kernel
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?
Thanks,
Frieder
[1] https://patchwork.kernel.org/cover/10643089/
[2]
https://github.com/torvalds/linux/blob/bab5c80b211035739997ebd361a679fa85b39465/drivers/net/usb/smsc95xx.c#L1382
^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: SMSC9730 Autosuspend/Resume Questions
2018-10-17 15:21 SMSC9730 Autosuspend/Resume Questions Frieder Schrempf
@ 2018-10-22 7:03 ` Nisar.Sayed
2018-10-22 7:14 ` Frieder Schrempf
0 siblings, 1 reply; 3+ messages in thread
From: Nisar.Sayed @ 2018-10-22 7:03 UTC (permalink / raw)
To: frieder.schrempf, steve.glendinning, UNGLinuxDriver, davem, netdev
Cc: oneukum, linux-usb, linux-kernel
Hi Frieder,
> 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.
- Nisar
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: SMSC9730 Autosuspend/Resume Questions
2018-10-22 7:03 ` Nisar.Sayed
@ 2018-10-22 7:14 ` Frieder Schrempf
0 siblings, 0 replies; 3+ messages in thread
From: Frieder Schrempf @ 2018-10-22 7:14 UTC (permalink / raw)
To: Nisar.Sayed, steve.glendinning, UNGLinuxDriver, davem, netdev
Cc: oneukum, linux-usb, linux-kernel
Hi Nisar,
On 22.10.18 09:03, Nisar.Sayed@microchip.com wrote:
> Hi Frieder,
>
>> 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
^ permalink raw reply [flat|nested] 3+ messages in thread
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