From: Pawel Laszczak <pawell@cadence.com> To: Roger Quadros <rogerq@ti.com>, Felipe Balbi <felipe.balbi@linux.intel.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org> Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>, "mark.rutland@arm.com" <mark.rutland@arm.com>, "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>, "hdegoede@redhat.com" <hdegoede@redhat.com>, "heikki.krogerus@linux.intel.com" <heikki.krogerus@linux.intel.com>, "andy.shevchenko@gmail.com" <andy.shevchenko@gmail.com>, "robh+dt@kernel.org" <robh+dt@kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "jbergsagel@ti.com" <jbergsagel@ti.com>, "nsekhar@ti.com" <nsekhar@ti.com>, "nm@ti.com" <nm@ti.com>, Suresh Punnoose <sureshp@cadence.com>, "peter.chen@nxp.com" <peter.chen@nxp.com>, Rahul Kumar <kurahul@cadence.com> Subject: RE: [PATCH v4 6/6] usb:cdns3 Fix for stuck packets in on-chip OUT buffer. Date: Thu, 7 Mar 2019 07:06:26 +0000 [thread overview] Message-ID: <BYAPR07MB4709F449E09AD352BA06CBA7DD4C0@BYAPR07MB4709.namprd07.prod.outlook.com> (raw) In-Reply-To: <70967a02-2f02-9ac8-e205-cdbfac5fbbae@ti.com> Hi, >Hi, > >On 21/02/2019 09:14, Felipe Balbi wrote: >> >> Hi, >> >> (please break your emails at 80-columns) >> >> Pawel Laszczak <pawell@cadence.com> writes: >>>>> One more thing. Workaround has implemented algorithm that decide for which >>>>> endpoint it should be enabled. e.g for composite device MSC+NCM+ACM it >>>>> should work only for ACM OUT endpoint. >>>>> >>>> >>>> If ACM driver didn't queue the request for ACM OUT endpoint, why does the >>>> controller accept the data at all? >>>> >>>> I didn't understand why we need a workaround for this. It should be standard >>>> behaviour to NAK data if function driver didn't request for all endpoints. >>> >>> Yes, I agree with you. Controller shouldn’t accept such packet. As I know this >>> behavior will be fixed in RTL. >>> >>> But I assume that some older version of this controller are one the market, >>> and driver should work correct with them. >>> >>> In the feature this workaround can be limited only to selected controllers. >>> >>> Even now I assume that it can be enabled/disabled by module parameter. >> >> no module parameters, please. Use revision detection in runtime. >> > >This is about whether to enable or disable the workaround. >By default we don't want this workaround to be enabled. > >I'm debating whether we should have this workaround at all or not. > >It has the following problems. > >1) It ACKs packets even when gadget end is not ready to accept the transfers. >2) It stores these packets in a temporary buffer and then pushes them to the >gadget driver whenever the gadget driver is ready to process the data. >3) Since the gadget driver can become ready at an indefinite time in the >future, it poses 2 problems: > a) It is sending stale data to the sink. (problematic at next protocol level?) > b) If this temporary buffer runs out we still hit the lock up issue. > >I think the right solution is to make sure that the gadget driver is always >reading all the enabled OUT endpoints *or* (keep the OUT endpoints disabled >if gadget driver is not ready to process OUT transfers). If driver disable endpoint then it not answer for packets from host. It will result that host reset the device, so I can't disable such endpoints. Other good solution is to change ACM driver in a way that it sends requests to controller driver after enabling endpoint. The class driver could decide what should do with such not expected packets. It could delete all or e.g keep only few last packets. This issue will be fixed in RTL but maybe driver should be compatible with previous controller’s version. By default, this workaround will be disabled or will depend on controller version. > >cheers, >-roger >-- >Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. >Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki Cheers, Pawel
WARNING: multiple messages have this Message-ID (diff)
From: Pawel Laszczak <pawell@cadence.com> To: Roger Quadros <rogerq@ti.com>, Felipe Balbi <felipe.balbi@linux.intel.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org> Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>, "mark.rutland@arm.com" <mark.rutland@arm.com>, "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>, "hdegoede@redhat.com" <hdegoede@redhat.com>, "heikki.krogerus@linux.intel.com" <heikki.krogerus@linux.intel.com>, "andy.shevchenko@gmail.com" <andy.shevchenko@gmail.com>, "robh+dt@kernel.org" <robh+dt@kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "jbergsagel@ti.com" <jbergsagel@ti.com>, "nsekhar@ti.com" <nsekhar@ti.com>, "nm@ti.com" <nm@ti.com>, Suresh Punnoose <sureshp@cadence.com>, "peter.chen@nxp.com" <peter.chen@nxp.com>, Rahul Kumar <kurahul@cadence.com> Subject: [v4,6/6] usb:cdns3 Fix for stuck packets in on-chip OUT buffer. Date: Thu, 7 Mar 2019 07:06:26 +0000 [thread overview] Message-ID: <BYAPR07MB4709F449E09AD352BA06CBA7DD4C0@BYAPR07MB4709.namprd07.prod.outlook.com> (raw) Hi, >Hi, > >On 21/02/2019 09:14, Felipe Balbi wrote: >> >> Hi, >> >> (please break your emails at 80-columns) >> >> Pawel Laszczak <pawell@cadence.com> writes: >>>>> One more thing. Workaround has implemented algorithm that decide for which >>>>> endpoint it should be enabled. e.g for composite device MSC+NCM+ACM it >>>>> should work only for ACM OUT endpoint. >>>>> >>>> >>>> If ACM driver didn't queue the request for ACM OUT endpoint, why does the >>>> controller accept the data at all? >>>> >>>> I didn't understand why we need a workaround for this. It should be standard >>>> behaviour to NAK data if function driver didn't request for all endpoints. >>> >>> Yes, I agree with you. Controller shouldn’t accept such packet. As I know this >>> behavior will be fixed in RTL. >>> >>> But I assume that some older version of this controller are one the market, >>> and driver should work correct with them. >>> >>> In the feature this workaround can be limited only to selected controllers. >>> >>> Even now I assume that it can be enabled/disabled by module parameter. >> >> no module parameters, please. Use revision detection in runtime. >> > >This is about whether to enable or disable the workaround. >By default we don't want this workaround to be enabled. > >I'm debating whether we should have this workaround at all or not. > >It has the following problems. > >1) It ACKs packets even when gadget end is not ready to accept the transfers. >2) It stores these packets in a temporary buffer and then pushes them to the >gadget driver whenever the gadget driver is ready to process the data. >3) Since the gadget driver can become ready at an indefinite time in the >future, it poses 2 problems: > a) It is sending stale data to the sink. (problematic at next protocol level?) > b) If this temporary buffer runs out we still hit the lock up issue. > >I think the right solution is to make sure that the gadget driver is always >reading all the enabled OUT endpoints *or* (keep the OUT endpoints disabled >if gadget driver is not ready to process OUT transfers). If driver disable endpoint then it not answer for packets from host. It will result that host reset the device, so I can't disable such endpoints. Other good solution is to change ACM driver in a way that it sends requests to controller driver after enabling endpoint. The class driver could decide what should do with such not expected packets. It could delete all or e.g keep only few last packets. This issue will be fixed in RTL but maybe driver should be compatible with previous controller’s version. By default, this workaround will be disabled or will depend on controller version. > >cheers, >-roger >-- >Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. >Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki Cheers, Pawel
next prev parent reply other threads:[~2019-03-07 7:06 UTC|newest] Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-02-14 19:45 [PATCH v4 0/6] Introduced new Cadence USBSS DRD Driver Pawel Laszczak 2019-02-14 19:45 ` Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 1/6] dt-bindings: add binding for USBSS-DRD controller Pawel Laszczak 2019-02-14 19:45 ` [v4,1/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 1/6] " Pawel Laszczak 2019-02-18 16:46 ` Rob Herring 2019-02-18 16:46 ` [v4,1/6] " Rob Herring 2019-02-18 16:46 ` [PATCH v4 1/6] " Rob Herring 2019-02-14 19:45 ` [PATCH v4 2/6] usb:common Separated decoding functions from dwc3 driver Pawel Laszczak 2019-02-14 19:45 ` [v4,2/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 2/6] " Pawel Laszczak 2019-02-19 13:14 ` Greg KH 2019-02-19 13:14 ` [v4,2/6] " Greg Kroah-Hartman 2019-02-20 6:28 ` [PATCH v4 2/6] " Pawel Laszczak 2019-02-20 6:28 ` [v4,2/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 3/6] usb:common Patch simplify usb_decode_set_clear_feature function Pawel Laszczak 2019-02-14 19:45 ` [v4,3/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 3/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 4/6] usb:common Simplify usb_decode_get_set_descriptor function Pawel Laszczak 2019-02-14 19:45 ` [v4,4/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 4/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 5/6] usb:cdns3 Add Cadence USB3 DRD Driver Pawel Laszczak 2019-02-14 19:45 ` [v4,5/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 5/6] " Pawel Laszczak 2019-02-15 9:57 ` Chunfeng Yun 2019-02-15 9:57 ` [v4,5/6] " Chunfeng Yun 2019-02-15 9:57 ` [PATCH v4 5/6] " Chunfeng Yun 2019-03-04 11:01 ` Pawel Laszczak 2019-03-04 11:01 ` [v4,5/6] " Pawel Laszczak 2019-03-04 11:01 ` [PATCH v4 5/6] " Pawel Laszczak 2019-03-04 12:46 ` Pawel Laszczak 2019-03-04 12:46 ` [v4,5/6] " Pawel Laszczak 2019-03-04 12:46 ` [PATCH v4 5/6] " Pawel Laszczak 2019-03-05 1:42 ` Chunfeng Yun 2019-03-05 1:42 ` [v4,5/6] " Chunfeng Yun 2019-03-05 1:42 ` [PATCH v4 5/6] " Chunfeng Yun 2019-02-19 13:24 ` Greg KH 2019-02-19 13:24 ` [v4,5/6] " Greg Kroah-Hartman 2019-03-04 9:23 ` [PATCH v4 5/6] " Pawel Laszczak 2019-03-04 9:23 ` [v4,5/6] " Pawel Laszczak 2019-02-20 13:04 ` [PATCH v4 5/6] " Roger Quadros 2019-02-20 13:04 ` [v4,5/6] " Roger Quadros 2019-02-20 13:04 ` [PATCH v4 5/6] " Roger Quadros 2019-03-07 5:37 ` Pawel Laszczak 2019-03-07 5:37 ` [v4,5/6] " Pawel Laszczak 2019-03-11 11:53 ` [PATCH v4 5/6] " Roger Quadros 2019-03-11 11:53 ` [v4,5/6] " Roger Quadros 2019-03-28 6:05 ` [PATCH v4 5/6] " Pawel Laszczak 2019-03-28 6:05 ` [v4,5/6] " Pawel Laszczak 2019-02-21 9:22 ` [PATCH v4 5/6] " Peter Chen 2019-02-21 9:22 ` [v4,5/6] " Peter Chen 2019-02-21 9:22 ` [PATCH v4 5/6] " Peter Chen 2019-03-07 9:52 ` Pawel Laszczak 2019-03-07 9:52 ` [v4,5/6] " Pawel Laszczak 2019-03-12 3:44 ` [PATCH v4 5/6] " Peter Chen 2019-03-12 3:44 ` [v4,5/6] " Peter Chen 2019-03-28 8:26 ` [PATCH v4 5/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 6/6] usb:cdns3 Fix for stuck packets in on-chip OUT buffer Pawel Laszczak 2019-02-14 19:45 ` [v4,6/6] " Pawel Laszczak 2019-02-14 19:45 ` [PATCH v4 6/6] " Pawel Laszczak 2019-02-20 10:24 ` Roger Quadros 2019-02-20 10:24 ` [v4,6/6] " Roger Quadros 2019-02-20 10:24 ` [PATCH v4 6/6] " Roger Quadros 2019-02-20 11:18 ` Pawel Laszczak 2019-02-20 11:18 ` [v4,6/6] " Pawel Laszczak 2019-02-20 13:17 ` [PATCH v4 6/6] " Roger Quadros 2019-02-20 13:17 ` [v4,6/6] " Roger Quadros 2019-02-20 15:50 ` [PATCH v4 6/6] " Pawel Laszczak 2019-02-20 15:50 ` [v4,6/6] " Pawel Laszczak 2019-02-21 7:14 ` [PATCH v4 6/6] " Felipe Balbi 2019-02-21 7:14 ` [v4,6/6] " Felipe Balbi 2019-02-21 7:14 ` [PATCH v4 6/6] " Felipe Balbi 2019-03-04 10:25 ` Roger Quadros 2019-03-04 10:25 ` [v4,6/6] " Roger Quadros 2019-03-07 7:06 ` Pawel Laszczak [this message] 2019-03-07 7:06 ` Pawel Laszczak 2019-03-07 9:13 ` [PATCH v4 6/6] " Roger Quadros 2019-03-07 9:13 ` [v4,6/6] " Roger Quadros 2019-03-11 8:15 ` [PATCH v4 6/6] " Peter Chen 2019-03-11 8:15 ` [v4,6/6] " Peter Chen 2019-03-11 8:15 ` [PATCH v4 6/6] " Peter Chen
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