Messages in this thread | | | Subject | Re: [RFC PATCH] soc: mediatek: Add support always on flag | From | Chunfeng Yun <> | Date | Wed, 24 Nov 2021 14:38:17 +0800 |
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On Thu, 2021-11-11 at 14:56 +0100, AngeloGioacchino Del Regno wrote: > Il 02/11/21 08:20, Chunfeng Yun ha scritto: > > There is a t-phy shared by PCIe and USB3 on mt8195, if the t-phy is > > used by PCIe, when power off its mtcmos, need software reset it > > (workaround way, usually hardware do it, but has an issue on > > mt8195), > > but it has side effect to USB2 phy(works with USB3 phy to support > > USB3.2 Gen1), so add support GENPD_FLAG_ALWAYS_ON flag, and make > > its > > power always on; > > Another reason is that USB3.2 Gen1/2 need keep power always on when > > support runtime-pm due to hardware limitation until now; > > > > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com> > > --- > > drivers/soc/mediatek/mt8195-pm-domains.h | 2 +- > > drivers/soc/mediatek/mtk-pm-domains.c | 2 ++ > > drivers/soc/mediatek/mtk-pm-domains.h | 1 + > > 3 files changed, 4 insertions(+), 1 deletion(-) > > > > Hello Chunfeng, > what are are the side effects on the USB2 PHY? Can you please expand? Sorry for later reply, I missed this message.
the side effect on u2 phy is that it will cause u2 phy power off and cause other issues, e.g. if there is a device plugged in u2 port, it will disconnect, more over it will not work until reboot platform.
> > Also, wouldn't it be possible to also reset the USB2 PHY when > resetting the t-phy > in order to get it back up and running? No, the usb driver don't reset or reinit phy after probe;
> > Moreover, as for the USB3.2 hardware limitation... I would say that > this is more > like something that has to be accounted for in the USB driver, > instead of the PM > domains driver... unless there's some reason that stops you from > doing that? Usb driver itself can't handle this case. but power domain's driver can handle it easily.
> > Thanks, > - Angelo
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