From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [PATCH v1 2/2] usb: tegra: Move UTMI-pads reset from ehci-tegra to tegra-phy Date: Mon, 11 Dec 2017 16:31:39 +0300 Message-ID: <886b6cfe-1691-508b-335b-6f015747dd40@gmail.com> References: <853ce44924e396b907332d4f3ad4ae70eae9bbcc.1512946782.git.digetx@gmail.com> <20171211102523.GH10671@ulmo> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171211102523.GH10671@ulmo> Content-Language: en-US Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding Cc: Felipe Balbi , Alan Stern , Greg Kroah-Hartman , Jonathan Hunter , linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 11.12.2017 13:25, Thierry Reding wrote: > On Mon, Dec 11, 2017 at 02:07:38AM +0300, Dmitry Osipenko wrote: >> UTMI pads are shared by USB controllers and reset of UTMI pads is shared >> with the reset of USB1 controller. Currently reset of UTMI pads is done by >> the EHCI driver and ChipIdea UDC works because EHCI driver always happen >> to be probed first. Move reset controls from ehci-tegra to tegra-phy in >> order to resolve the problem. >> >> Signed-off-by: Dmitry Osipenko >> --- >> drivers/usb/host/ehci-tegra.c | 87 ++++++++++++++++++--------------------- >> drivers/usb/phy/phy-tegra-usb.c | 46 +++++++++++++++++++++ >> include/linux/usb/tegra_usb_phy.h | 2 + >> 3 files changed, 87 insertions(+), 48 deletions(-) > > I don't think we can do this. For one I don't think shared resets are > going to work here because you really won't ever be able to reset after > two devices have requested the same reset. Ah, indeed. Originally I had the reset being done in the probe, but then changed it in the last minute without proper testing. Good catch! I'll revert back patch to the origin. Second, utmip_pad_close() > could be called at any point and it will have the side-effect of either > not doing a reset at all (because it is shared) or resetting the USBD > controller at the same time. utmip_pad_close() is only called on tegra-phy driver removal, so it is absolutely fine. > We've been over this code a great deal over the years. I'd love it to be > simpler, but every time we tried to simplify it, things broke. Well, the current code is already broken quite severely because now we have two users of the tegra-phy: ehci-tegra and chipidea-tegra. Things brake if host driver is loaded after the UDC because host would reset the UDC. And also pads won't be reset if ehci-tegra isn't loaded at all. Shared reset seems to be a perfect solution for us and of course it requires extra carefulness. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html