On Thu, 2021-11-11 at 14:56 +0100, AngeloGioacchino Del Regno wrote:

Il 02/11/21 08:20, Chunfeng Yun ha scritto:

quoted

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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