On Wed, 16 Jan 2013 12:57:08 +0200 Roger Quadros <rogerq@xxxxxx> wrote: > On 01/16/2013 12:27 PM, NeilBrown wrote: > > On Wed, 16 Jan 2013 12:00:48 +0200 Roger Quadros <rogerq@xxxxxx> wrote: > > > >> On 01/09/2013 12:29 AM, NeilBrown wrote: > >>> > >>> Hi, > >>> I'm trying to get off_mode working reliably on my gta04 mobile phone. > >>> > >>> My current stumbling block is USB. The "Option" GSM module is attached via > >>> USB (there is a separate transceiver chip attached to port 1 which is placed > >>> in OMAP_EHCI_PORT_MODE_PHY). > >>> > >>> After a suspend/resume cycle with off_mode enabled the GSM module disappears. > >>> i.e. 'lsusb' doesn't see it any more and the various ttyHSxx devices don't > >>> exist. > >>> Without off mode, the modem always appears after resume. > >>> > >>> I discovered that the registers set by: > >>> > >>> drivers/mfd/omap-usb-host.c > >>> > >>> are not maintained across as suspend/resume so I added the following patch > >>> (which I can make a formal submission of if it looks right to others), but > >>> that didn't help (or didn't help enough). > >>> > >>> If I > >>> > >>> echo 1 > /sys/kernel/debug/pm_debug/usbhost_pwrdm/suspend > >>> > >>> thus keeping just the USBHOST power domain out of off_mode, the GSM module > >>> doesn't disappear. So it seems that some context in the usbhost domain is > >>> not being save and restored. > >>> > >>> This is as far as I can get. Can someone suggest where I should look to find > >>> out what is not being saved/restored properly, and how to go about saving and > >>> restoring? > >> > >> You need to ensure that USBHOST/TLL context is saved as per the Save and > >> Restore sequence see section "USBHOST/USBTLL Save-and-Restore > >> Management" in the OMAP Technical Reference Manual. > >> > >> The basic idea there is that software does the context saving into SAR > >> RAM before entering OFF mode and hardware automatically restores the > >> context after coming out of OFF mode. > > > > Is it? The way I read the doco, the hardware both saves to SAR RAM, and > > restores from SAR RAM. > > Section 22.2.4.1.6 Save and Restore > > of my copy of the TRM says: > > > >> The save-and-restore (SAR) mechanism can extract the hardware context of the high-speed USB host > >> controller (after all USB activity has been suspended) before switching off (=save), save it to an external > >> always-on memory, and reinject it later after the module has been switched on again and reset (=restore) > >> seamlessly for the USB. Part of that context is composed of the register fields described in the current > >> chapter. The rest of the context is composed of the "buried" flip-flops and memories (not accessible by > >> software) like finite state-machine (FSM) states, buffer contents, and miscellaneous random logic bits. > > > > which strongly suggests that it is all handled by hardware. Of course there > > are other registers that aren't covered by the SAR - we need to identify > > those and make sure they are saved and restored. I've found a few registers > > that aren't being restored, but restoring them hasn't made a visible > > difference yet. > > Yes, you are right. I mixed it up with OMAP4 behaviour, sorry. > But still, software needs to ensure that the USBHOST and CORE power > domain's SAVEANDRESTORE bit are set to ensure that SAR works. > > see section "3.5.4.6 USBHOST/USBTLL Save-and-Restore Management" > > This seems to be done by the powerdomain code based on the > PWRDM_HAS_HDWR_SAR flag. However, this flag is disabled for USBHOST > powerdomain with the following comment. > > > Both USBHOST and USBTLL support a save-and-restore mechanism. When the device enters into off > > mode (that is, all power domains, except the WKUP power domain, are off), the user may want to save > > the USBHOST context and restore it when exiting off mode. The save-and-restore mechanism for the HS > > USB Host is enabled by setting the PRCM.PM_PWSTCTRL_USBHOST[4] SAVEANDRESTORE bit; for > > the USBTLL, it is configured by the PRCM.PM_PWSTCTRL_CORE[4] SAVEANDRESTORE bit. The save > > mechanism is initiated as the power domain transitions from active to off state (or to OSWR state for the > > USBTLL), whereas the restore mechanism is initiated as the power domain transitions from off to active > > power state. > > Can you try with the flag enabled? If I keep CORE and USBHOST out of off-mode (by writing to the relevant 'suspend' files in /sys/kernel/debug/pm-debug) then it all works. If I set this flag, then I can allow USBHOST to enter off-mode as long as I keep CORE in retention or better. If I let CORE and USBHOST go to off-mode and don't have the flag set, then I can resume from suspend, but the usb modem has disappeared. If I let CORE and USBHOST go to off-mode and DO have the flag set, then I cannot even resume from suspend.... sometimes. I hate those "sometimes"s! If I remove the battery (with no other power source present) and re-insert it, and let the phone boot up to stable state and then enter suspend, I cannot resume from suspend. (I tried setting "no_console_suspend" to see if anything was happening - but that keeps CORE awake). If I do the same but before it suspends I: echo 1 > /sys/kernel/debug/pm_debug/core_pwrdm/suspend then let is suspend and resume, the resume works. Then I: echo 0 > /sys/kernel/debug/pm_debug/core_pwrdm/suspend to allow full sleep mode and now suspend, and again resume works. And it continues to work. And the USB modem remains visible - it doesn't disconnect at all. So.... something very odd is happening somewhere. Maybe the USBHOST powerdomain isn't really going to off-mode again after the first time like the comment in powerdomains3xxx_data.c says: /* * REVISIT: Enabling usb host save and restore mechanism seems to * leave the usb host domain permanently in ACTIVE mode after * changing the usb host power domain state from OFF to active once. * Disabling for now. */ However the /sys/kernel/debug/pm_debug/count file shows the "OFF" count for usbhost_pwrdm increments on each suspend, and that seems to be based on info read out of the the OMAP3 itself.... All very odd. Thanks, NeilBrown
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