Hi, On Thursday 06 August 2015 02:17 PM, Tony Lindgren wrote: > * Kishon Vijay Abraham I <kishon@xxxxxx> [150805 07:10]: >> On Wednesday 05 August 2015 01:31 PM, Tony Lindgren wrote: >>> >>> We don't have syscon-otghs and to me it seems we need a PHY driver >>> as I pointed out at: >> >> If *syscon-otghs* is not present, then it'll fall-back to using the *ctrl-module*. > > OK great. > >>> >>> https://lkml.org/lkml/2015/6/24/231 >> >> Maybe I should have explained this in the previous thread. The *otghs* register >> that we are trying to access here does _not_ belong to the PHY. It acts as >> mailbox register from MUSB glue (TI integration layer) to MUSB core. That's why >> it's programmed in the TI glue layer (omap2430.c). >> >> Even when we were using the older API [omap_control_usb_set_mode()], we first >> call omap_musb_mailbox from the PHY drivers (phy-twl4030-usb.c, >> phy-twl6030-usb.c) and then omap_musb_mailbox in the TI glue writes to the >> control module instead of PHY drivers directly calling omap_control_usb_set_mode(). > > Hmm looking at "Table 18-204. CONTROL_USBOTGHS_CONTROL" it seems to mention > "transceiver" for quite a few bitfields :) Probably what that register does > is control a PHY over ULPI. OMAP4 uses UTMI PHY and it uses CONTROL_USBOTGHS_CONTROL too. > > So from Linux kernel point of view we're best off treating it as a PHY. > It seems it should have a minimal PHY driver similar to what we have for > dm816x control module in drivers/phy/phy-dm816x-usb.c. hmm.. IMHO CONTROL_USBOTGHS_CONTROL register belongs to the TI MUSB glue and should be programmed in omap2430.c. It's better to get the opinion of Felipe here. Felipe? > > For reference, here is the register bitfields pasted from 4460 TRM: > > Table 18-204. CONTROL_USBOTGHS_CONTROL, p3972 > Physical Address 0x4A00 233C > > BIT NAME DESCIPTION > 8 DISCHRGVBUS ... OTG transceiver does (not) discharge VBUS ... > 7 CHRGVBUS ... OTG transceiver does (not) charge VBUS ... > 6 IDPULLUP ... OTG transceiver does (not) drive VBUS ... > 4 IDDIG ... OTG transceiver does (not) apply a pullup to ID ... > 3 SESSEND ... VBUS voltage is above/below VB_SESS_END ... > 2 VBUSVALID ... VBUS is above the threshold ... > 1 BVALID ... VBUS voltage is above/below VB_SESS_VLD ... > 0 AVALID ... BUS voltage is above/below VA_SESS_VLD ... > > So how about just adding ONTROL_USBOTGHS_CONTROL support to the existing > drivers/phy/phy-omap-usb2.c instead? It seems that it should allow us > to completely get rid of the custom mailbox stuff for MUSB 2430 support? Not in phy-omap-usb2.c. It's the UTMI PHY driver and is not used by OMAP3 based boards (uses twl4030 ULPI PHY). CONTROL_USBOTGHS_CONTROL has to be programmed for OMAP3 also. Thanks Kishon -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
