From: Felipe Balbi <balbi@kernel.org>
To: Michael Grzeschik <mgr@pengutronix.de>,
Manish Narani <manish.narani@xilinx.com>
Cc: gregkh@linuxfoundation.org, robh+dt@kernel.org,
michal.simek@xilinx.com, p.zabel@pengutronix.de,
devicetree@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, git@xilinx.com,
linux-arm-kernel@lists.infradead.org, kernel@pengutronix.de
Subject: Re: [RESEND PATCH v3 2/2] usb: dwc3: Add driver for Xilinx platforms
Date: Mon, 18 Jan 2021 17:24:38 +0200 [thread overview]
Message-ID: <87r1miuv2h.fsf@kernel.org> (raw)
In-Reply-To: <20210118134223.GE12316@pengutronix.de>
Hi,
Michael Grzeschik <mgr@pengutronix.de> writes:
> On Tue, Dec 15, 2020 at 12:24:51PM +0530, Manish Narani wrote:
>>Add a new driver for supporting Xilinx platforms. This driver is used
>>for some sequence of operations required for Xilinx USB controllers.
>>This driver is also used to choose between PIPE clock coming from SerDes
>>and the Suspend Clock. Before the controller is out of reset, the clock
>>selection should be changed to PIPE clock in order to make the USB
>>controller work. There is a register added in Xilinx USB controller
>>register space for the same.
>
> I tried out this driver with the vanilla kernel on an zynqmp. Without
> this patch the USB-Gadget is already acting buggy. In the gadget mode,
> some iterations of plug/unplug results to an stalled gadget which will
> never come back without a reboot.
>
> With the corresponding code of this driver (reset assert, clk modify,
> reset deassert) in the downstream kernels phy driver we found out it is
> totaly stable. But using this exact glue driver which should do the same
> as the downstream code, the gadget still was buggy the way described
> above.
>
> I suspect the difference lays in the different order of operations.
> While the downstream code is runing the resets inside the phy driver
> which is powered and initialized in the dwc3-core itself. With this glue
> layser approach of this patch the whole phy init is done before even
> touching dwc3-core in any way. It seems not to have the same effect,
> though.
>
> If really the order of operations is limiting us, we probably need
> another solution than this glue layer. Any Ideas?
might be a good idea to collect dwc3 trace events. Can you do that?
--
balbi
next prev parent reply other threads:[~2021-01-18 15:31 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 6:54 [RESEND PATCH v3 0/2] Add a separate DWC3 OF driver for Xilinx platforms Manish Narani
2020-12-15 6:54 ` [RESEND PATCH v3 1/2] dt-bindings: usb: dwc3-xilinx: Add documentation for Versal DWC3 Controller Manish Narani
2020-12-15 6:54 ` [RESEND PATCH v3 2/2] usb: dwc3: Add driver for Xilinx platforms Manish Narani
2020-12-21 18:05 ` Michael Tretter
2021-01-18 13:42 ` Michael Grzeschik
2021-01-18 15:24 ` Felipe Balbi [this message]
2021-01-19 16:39 ` Michael Grzeschik
2021-01-22 8:08 ` Michael Grzeschik
2021-01-22 13:06 ` Manish Narani
2021-01-22 13:34 ` Michael Grzeschik
2021-01-27 23:36 ` Michael Grzeschik
2021-02-08 23:56 ` Michael Grzeschik
2021-02-09 6:01 ` Manish Narani
2021-02-09 20:02 ` Michael Grzeschik
2021-02-10 12:07 ` Michael Grzeschik
2021-02-22 15:31 ` Michael Grzeschik
2021-02-25 11:41 ` Manish Narani
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