linux-kernel - Re: [patch 4/7] ps3: Storage Driver Probing

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Date:	Fri, 25 May 2007 21:48:39 +0200 (CEST)
From:	Geert Uytterhoeven <Geert.Uytterhoeven@...ycom.com>
To:	Arnd Bergmann <arnd@...db.de>
cc:	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 4/7] ps3: Storage Driver Probing

On Fri, 25 May 2007, Arnd Bergmann wrote:
> On Friday 25 May 2007, Geert.Uytterhoeven@...ycom.com wrote:
> > +static u64 ps3stor_wait_for_completion(u64 devid, u64 tag,
> > +				       unsigned int timeout)
> > +{
> > +	unsigned int retries = 0;
> > +	u64 res = -1, status;
> > +
> > +	for (retries = 0; retries < timeout; retries++) {
> > +		res = lv1_storage_check_async_status(NOTIFICATION_DEVID, tag,
> > +						     &status);
> > +		if (!res)
> > +			break;
> > +		set_current_state(TASK_INTERRUPTIBLE);
> > +		schedule_timeout(1);
> > +	}
> 
> Any reason not to use msleep(1) instead of the schedule_timeout?

Not really. I'll change it.

> > +	switch (dev_type) {
> > +	case PS3_DEV_TYPE_STOR_DISK:
> > +		match_id = PS3_MATCH_ID_STOR_DISK;
> > +		break;
> > +
> > +	case PS3_DEV_TYPE_STOR_ROM:
> > +		match_id = PS3_MATCH_ID_STOR_ROM;
> > +		break;
> > +
> > +	case PS3_DEV_TYPE_STOR_FLASH:
> > +		match_id = PS3_MATCH_ID_STOR_FLASH;
> > +		break;
> > +
> > +	default:
> > +		return 0;
> > +	}
> 
> Why do you have separate constants for PS3_DEV_TYPE_* and
> PS3_MATCH_ID_*? If you don't do any conversion, this driver
> will immediately work for additional types as well, if more
> get added later.

The PS3_DEV_TYPE_* IDs are imposed by the repository, as created by the
hypervisor.
The PS3_MATCH_ID_* IDs are created by us, for all PS3-specific devices.
As Geoff already pointed out, we may be able to use PS3_DEV_TYPE_* IDs for
everything, but unfortunately not all PS3-specific devices are present in the
repository.

> > +
> > +//		pr_debug("%s:%u: Checking for new storage devices...\n",
> > +//			 __func__, __LINE__);
> 
> Should be removed, or not in comments, either way is fine, as pr_debug
> normally does not get compiled in anyway.

Oops, forgot to uncomment it (it was a bit noisy while I lived with DEBUG
defined ;-)

> > +		msleep_interruptible(ms);
> > +		if (ms < 60000)
> > +			ms <<= 1;
> 
> Is this timeout only for the disk spinup, or also for detecting media
> added at run time, like inserting a DVD? One minute timeout for
> detecting a DVD would sound very long to me.

It's not for inserting DVDs, only for new devices showing up in the repository.
Apparently new devices may keep on showing up a while after boot up, but I
think this matters only for the kboot kernel, that's why I went with the
exponential back-off with upper limit.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- Sony Network and Software Technology Center Europe (NSCE)
Geert.Uytterhoeven@...ycom.com ------- The Corporate Village, Da Vincilaan 7-D1
Voice +32-2-7008453 Fax +32-2-7008622 ---------------- B-1935 Zaventem, Belgium
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