Messages in this thread | | | Subject | Re: [PATCH] usb: phy: add dedicated notifier for charger events | From | Ivaylo Dimitrov <> | Date | Mon, 5 Dec 2022 22:29:13 +0200 |
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On 16.11.22 г. 9:11 ч., Ivaylo Dimitrov wrote: > > > On 14.11.22 г. 18:46 ч., Ivaylo Dimitrov wrote: >> Hi, >> >> On 14.11.22 г. 18:14 ч., Greg KH wrote: >>> On Mon, Nov 14, 2022 at 02:56:02PM +0200, Ivaylo Dimitrov wrote: >>>> usb_phy::notifier is already used by various PHY drivers (including >>>> phy_generic) to report VBUS status changes and its usage conflicts with >>>> charger current limit changes reporting. >>> >>> How exactly does it conflict? >>> >> >> see below >> >>>> Fix that by introducing a second notifier that is dedicated to usb >>>> charger >>>> notifications. Add usb_charger_XXX_notifier functions. Fix charger >>>> drivers >>>> that currently (ab)use usb_XXX_notifier() to use the new API. >>> >>> Why not just set the notifier type to be a new one instead of adding a >>> whole new notifier list? Or use a real callback? notifier lists are >>> really horrid and should be avoided whenever possible. >>> >> >> Not sure what you mean by "notifier type', but if that is that val >> parameter of atomic_notifier_call_chain(), the way it is used by usb >> charger FW: >> >> https://elixir.bootlin.com/linux/latest/source/drivers/usb/phy/phy.c#L132 >> >> is not compatible with: >> >> https://elixir.bootlin.com/linux/latest/source/drivers/usb/phy/phy-generic.c#L185 >> >> >> for example, IIUC. >> >> The former wants to send max current as val, while latter sends event >> type as val. Sure, I may create some kind of hack, like using the MSB >> to denote charger events, but that doesn't feel right. >> >> Or, shall I do something else and fix the usage all over the place? >> Please elaborate. >> > > Digging further into that, it seems phy-ab8500-usb.c is also using > usb_phy::notifier in non-standard way, it sends events from > ux500_musb_vbus_id_status instead of usb_phy_events. I don't know the > history behind, but right now we have at least 3 incompatible usages of > usb_phy::notifier: > > 1. Most of the phy and charger drivers use usb_phy_events as notifier type > > 2. phy-ab8500-usb.c uses ux500_musb_vbus_id_status as notifier type, I > am not the only one to hit that it seems > https://elixir.bootlin.com/linux/v6.1-rc5/source/drivers/power/supply/ab8500_charger.c#L3191 > > > 3. USB charger framework uses max charging current as notifier type. > > Moreover, a charger driver in a system that has gadget drivers support > and phy that has extcon charger cable detection support and registers to > phy notifier, will inevitably receive (1) and (3) types of > notifications, without any way to distinguish I was able to find. > > I don't really see how those can be merged to use one notifier only, > without fixing most of USB phy and gadget drivers and half of charger > drivers. Not that I like adding the second notifier, I just don;t see > other way. > > Regards, > Ivo > >> In regards to callback - I didn't want to come-up with a whole new >> API, but just fix the current one. Also, a single callback will not be >> enough - imagine a case with 2 batteries that have to be charged by a >> single USB port, so 2 separate charger devices, most-probably. We will >> have to keep a list of callback functions somehow. I admit my lack of >> knowledge, but, do we already have such API to use? >> >>>> Fixes: a9081a008f84 ("usb: phy: Add USB charger support") >>>> >>>> Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com> >>> >>> You can't have a blank line between there, checkpatch.pl should have >>> complained. >>> >> >> it didn't: >> >> ./scripts/checkpatch.pl >> 0001-usb-phy-add-dedicated-notifier-for-charger-events.patch >> total: 0 errors, 0 warnings, 90 lines checked >> >> 0001-usb-phy-add-dedicated-notifier-for-charger-events.patch has no >> obvious style problems and is ready for submission. >> >> Will fix, if I am to send v2 >> >> Thanks, >> Ivo >> >>> thanks, >>> >>> greg k-h >>>
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