On Sun, Sep 30, 2012 at 12:27:41AM +0200, Rafael J. Wysocki wrote: > On Saturday, September 29, 2012, Aaron Lu wrote: > > [Adding more people and list back in] > > > > On 09/29/2012 05:46 AM, Rafael J. Wysocki wrote: > > > On Friday, September 28, 2012, Aaron Lu wrote: > > >> On 09/28/2012 07:15 AM, Rafael J. Wysocki wrote: > > >>> On Thursday, September 27, 2012, Aaron Lu wrote: > > >>>> On 09/27/2012 05:37 AM, Rafael J. Wysocki wrote: > > >>>>> > > >>>>> Say the user has pressed the eject button. What does need to happen so that > > >>>>> the tray is physically ejected? > > >>>> > > >>>> The tray is ejected by the ODD itself, host does not have to do anything. > > >>>> > > >>>> There is a command(PREVENT_MEDIUM_REMOVAL) to lock the door so that when > > >>>> user presses the eject button, the tray will not be ejected. This command > > >>>> is usually sent when we have a disc inside and a user space program > > >>>> opened the underlying block device(e.g. /dev/sr0) to read/write data. > > >>>> > > >>>> And host can also eject the tray by sending a START_STOP_UNIT command > > >>>> with param LoEj set to 1 and we have a function called sr_tray_move to > > >>>> do just this. And this is also what I've used to eject the tray after > > >>>> user wakes up the ODD, as when user presses the eject button when the > > >>>> ODD is in zero power state, it can't eject the tray as usual, so host > > >>>> software will need to do this, that's the reason I need to know such > > >>>> information: > > >>>> When ODD is resumed, is it because user wakes it up? > > >>> > > >>> But START_STOP_UNIT eventually causes ata_scsi_start_stop_xlat() to be > > >> > > >> You are following ata case, while the ODD is an atapi device :-) > > >> The translation function is atapi_xlat, but that doesn't affect the idea > > >> here. > > >> > > >>> executed, so I wonder if we really need to go up through the SCSI stack > > >>> to send that command to the drive from there? It should be possible > > >>> to issue STANDBY/READ VERIFY to the device directly from libata if > > >>> an eject event is signaled through a GPE. > > >> > > >> Yes, this is possible. > > >> Though it doesn't feel very cool, since I have no idea if the ODD is a > > >> tray type or slot type in ATA layer and I'll blindly send this command > > >> to it then, not a problem maybe. > > > > > > It would be good to verify if that works for slot devices, if possible. > > > > The ACPI GPE event is triggered when user inserts a disc into a slot > > type ODD, and if I send an eject command to it, the disc will be > > ejected, which is wrong. > > > > I need to know the loading mechanism(tray type or slot type) of the ODD > > to decide if I should send this command. > > > > > > > >> And what do you think of moving the acpi notification code to sr? > > >> http://marc.info/?l=linux-pm&m=134873904332704&w=4 > > > > > > I don't think this is a good idea, quite frankly. sr seems to be a too > > > generic place for that. > > > > Does this mean sr can only have code that is useful to all devices it > > manages? i.e. If a piece of code enables a feature for a special kind of > > ODD(like the sata based ZPODD), it shouldn't be done in sr? > > If the feature is specific to one special kind of ODD only, then I don't > think sr is the right place to add support for it. > > > > Ideally, the whole ZPODD handling should not be visible to the SCSI layer, > > > > I can see 2 problems: > > - Don't know its loading machanism so we have the problem above; > > Does using the need_eject flag address this problem somehow? The need_eject flag is used to give sr a hint that on resume, please eject its tray. And sr knows what loading mechanism this ODD is. > > > - Need to send command to find out if ODD is zero power ready somewhere > > in ata layer, this implies the device is doing IO after it is runtime > > suspended in scsi layer. > > There's nothing wrong with accessig suspended devices as long as we know > that they will respond. :-) Oh, I was reading the comments above the struct dev_pm_ops in /include/linux/pm.h and thought that was a requirement :-) Thanks, Aaron > > > > perhaps except the "no_polling" flag disabling the polling that may be > > > useful for other purposes in principle. > > > > I hope so, let's hear what other people has to say. > > > > > > > > I'm not sure if it's possible at this point, but if not we need to know > > > very precisely why not. > > > > There is nothing in theory stopping us from doing this in ata layer. > > For the loading mechanism, we can always send an ATAPI command to figure > > it out. > > > > So gentlemen, I need your opinions on where this ZPODD code should live > > before I can continue this work, thanks. > > I would _try_ to add it at the ATA level. > > Thanks, > Rafael > -- > To unsubscribe from this list: send the line "unsubscribe linux-ide" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
