if_spi: howto implement suspend/resume?

[Dan Williams]

On Sun, 2009-04-19 at 09:59 +0300, Mike Rapoport wrote:
> 
> Dan Williams wrote:
> > On Fri, 2009-04-17 at 18:24 +0200, Uli Luckas wrote:
> >> Hi all,
> >> I am trying to implement suspend/resume support for libertas_spi as suspending 
> >> a device with the libertas_spi driver loaded now crashes the kernel.
> >> As I have no firmware documentation, I naively followed the if_usb driver.
> >> As expected this did not work. With the patch below the kernel does not crash 
> >> any more but the libertas chip is non-functional after resume:
> >> Apr 17 18:14:51 [kernel] [    0.000931] libertas: I/O error
> 
> [ snip ]
> 
> >> Apr 17 18:14:51 [kernel] [    0.495033] libertas: DNLD_CMD: hw_host_to_card 
> >> failed: -22
> >>
> >> Can anybody sched some ligt on how to approach suspend functionality in 
> >> if_spi?
> > 
> > Does SPI suspend cut power to the libertas chip?  Does it do
> > bus-specific low-power stuff?  The current suspend code assumes that the
> > libertas chip does not require complete reinitialization (ie, new
> > firmware load, etc), which of course implies that the libertas chip is
> > still powered across suspend so that when the host wakes up, a command
> > can simply be sent to the card that will wake it up.
> 
> I think that suspend behavior is machine dependent. In the hardware I have the
> power to the libertas chip is cut during suspend, but in other platforms the
> chip may be powered on.

Then yeah, suspend/resume here needs to be reworked to re-init the chip
on resume.  The OLPC use-case is "special", and it's certainly not the
norm.

Dan

> > That is an artifact of the OLPC use-case, which isn't necessarily
> > applicable elsewhere.
> > 
> > Dan
> > 
> >> Thanks
> >> Uli
> >>
> >>
> >> Index: drivers/net/wireless/libertas/if_spi.c
> >> ===================================================================
> >> --- drivers/net/wireless/libertas/if_spi.c	(revision 11391)
> >> +++ drivers/net/wireless/libertas/if_spi.c	(working copy)
> >> @@ -31,6 +31,7 @@
> >>  #include "decl.h"
> >>  #include "defs.h"
> >>  #include "dev.h"
> >> +#include "cmd.h"
> >>  #include "if_spi.h"
> >>  
> >>  struct if_spi_packet {
> >> @@ -1139,6 +1140,10 @@
> >>  	if (err)
> >>  		goto release_irq;
> >>  
> >> +	priv->wol_gpio = 2; /* Wake via GPIO2... */
> >> +	priv->wol_gap = 20; /* ... after 20ms    */
> >> +	lbs_host_sleep_cfg(priv, EHS_WAKE_ON_UNICAST_DATA);
> >> +
> >>  	lbs_deb_spi("Finished initializing WLAN module.\n");
> >>  
> >>  	/* successful exit */
> >> @@ -1183,9 +1188,49 @@
> >>  	return 0;
> >>  }
> >>  
> >> +#ifdef CONFIG_PM
> >> +static int if_spi_suspend(struct spi_device *spi, pm_message_t mesg)
> >> +{
> >> +	struct if_spi_card *card = spi_get_drvdata(spi);
> >> +	struct lbs_private *priv = card->priv;
> >> +	int ret;
> >> +
> >> +	lbs_deb_enter(LBS_DEB_USB);
> >> +
> >> +	ret = lbs_suspend(priv);
> >> +	if (ret)
> >> +		goto out;
> >> +
> >> + out:
> >> +	lbs_deb_leave(LBS_DEB_USB);
> >> +	return ret;
> >> +}
> >> +
> >> +static int if_spi_resume(struct spi_device *spi)
> >> +{
> >> +	struct if_spi_card *card = spi_get_drvdata(spi);
> >> +	struct lbs_private *priv = card->priv;
> >> +
> >> +	lbs_deb_enter(LBS_DEB_USB);
> >> +
> >> +	up(&card->spi_ready);
> >> +
> >> +	lbs_resume(priv);
> >> +
> >> +	lbs_deb_leave(LBS_DEB_USB);
> >> +	return 0;
> >> +}
> >> +#else
> >> +#define if_spi_suspend NULL
> >> +#define if_spi_resume NULL
> >> +#endif
> >> +
> >> +
> >>  static struct spi_driver libertas_spi_driver = {
> >>  	.probe	= if_spi_probe,
> >>  	.remove = __devexit_p(libertas_spi_remove),
> >> +	.suspend = if_spi_suspend,
> >> +	.resume = if_spi_resume,
> >>  	.driver = {
> >>  		.name	= "libertas_spi",
> >>  		.bus	= &spi_bus_type,
> >>
> >> -- 
> >>
> >> ------- ROAD ...the handyPC Company - - -  ) ) )
> >>
> >> Uli Luckas
> >> Head of Software Development
> >>
> >> ROAD GmbH
> >> Bennigsenstr. 14 | 12159 Berlin | Germany
> >> fon: +49 (30) 230069 - 62 | fax: +49 (30) 230069 - 69
> >> url: www.road.de
> >>
> >> Amtsgericht Charlottenburg: HRB 96688 B
> >> Managing director: Hans-Peter Constien
> >>
> >>
> >> _______________________________________________
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> > 
> > 
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