Re: [rt2x00-users] [PATCH] [RFC] rt2500pci: fix powersaving

[Ondrej Zary <linux@rainbow-software.org>]

On Tuesday 30 March 2010 23:02:33 Gertjan van Wingerde wrote:
> On 03/30/10 22:09, Ondrej Zary wrote:
> > On Tuesday 30 March 2010, Matthijs Kooijman wrote:
> >> Hi all,
> >>
> >>> phy0 -> rt2500pci_set_device_state: Error - Device failed to enter
> >>> state 1 (-16).
> >>
> >> I'm seeing this one on my rt2500pci as well (and also works ok
> >> otherwise).
> >
> > OK, so let's try to fix it.
> >
> > The first patch below fixes this problem. And reveals two other problems.
> > Now the device has problems entering states 3 and 4 (remains stuck in
> > state 1) - the driver seems to not like this and oopses.
> > The second patch fixes the "stuck state 1" problem (same fix as in
> > rt2500usb). The oops does not appear anymore with the second patch - but
> > I think that it should be fixed anyway separately.
> > (I'm testing this with "while true; do ifdown wlan0; ifup wlan0; done")
>
> Thanks again for your hard and persistent work on this.
>
> > oops removed
> >
> >
> > ---
> > linux-2.6.34-rc2-orig/drivers/net/wireless/rt2x00/rt2500pci.c	2010-03-20
> > 02:17:57.000000000 +0100 +++
> > linux-2.6.34-rc2/drivers/net/wireless/rt2x00/rt2500pci.c	2010-03-30
> > 15:04:50.000000000 +0200 @@ -1079,7 +1079,7 @@
> >  static int rt2500pci_set_state(struct rt2x00_dev *rt2x00dev,
> >  			       enum dev_state state)
> >  {
> > -	u32 reg;
> > +	u32 reg, reg2;
> >  	unsigned int i;
> >  	char put_to_sleep;
> >  	char bbp_state;
> > @@ -1100,11 +1100,12 @@
> >  	 * device has entered the correct state.
> >  	 */
> >  	for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
> > -		rt2x00pci_register_read(rt2x00dev, PWRCSR1, &reg);
> > -		bbp_state = rt2x00_get_field32(reg, PWRCSR1_BBP_CURR_STATE);
> > -		rf_state = rt2x00_get_field32(reg, PWRCSR1_RF_CURR_STATE);
> > +		rt2x00pci_register_read(rt2x00dev, PWRCSR1, &reg2);
> > +		bbp_state = rt2x00_get_field32(reg2, PWRCSR1_BBP_CURR_STATE);
> > +		rf_state = rt2x00_get_field32(reg2, PWRCSR1_RF_CURR_STATE);
> >  		if (bbp_state == state && rf_state == state)
> >  			return 0;
> > +		rt2x00pci_register_write(rt2x00dev, PWRCSR1, reg);
> >  		msleep(10);
> >  	}
>
> Hmmm, checking the old legacy Ralink rt2500 driver it shows that the legacy
> driver never waits and checks whether the device has come in the right
> power state. What does happen to the stability of the connection if you
> simply remove this entire for-loop?

It works without the loop - But I suspect that the device never enters 
STATE_SLEEP. With the loop present, it needs 3 loop passes to enter 
STATE_SLEEP (with that register write added). It never enters STATE_SLEEP 
without that added register write (I took it from rt2500usb) and that's why 
the error message was printed in log.

-- 
Ondrej Zary