[lkml]   [2021]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RESEND PATCH v3 2/2] usb: dwc3: Add driver for Xilinx platforms
Adding Tinh Nguyen to CC:

On Tue, Feb 09, 2021 at 09:02:00PM +0100, Michael Grzeschik wrote:
>Hi Manish,
>On Tue, Feb 09, 2021 at 06:01:58AM +0000, Manish Narani wrote:
>>Hi Michael,
>>>-----Original Message-----
>>>From: Michael Grzeschik <>
>>>Sent: Tuesday, February 9, 2021 5:26 AM
>>>To: Manish Narani <>
>>>;; linux-
>>>;; Michal Simek
>>><>; git <>;; linux-
>>>Subject: Re: [RESEND PATCH v3 2/2] usb: dwc3: Add driver for Xilinx
>>>Hi Manish!
>>>On Thu, Jan 28, 2021 at 12:36:07AM +0100, Michael Grzeschik wrote:
>>>>On Fri, Jan 22, 2021 at 02:34:52PM +0100, Michael Grzeschik wrote:
>>>>>On Fri, Jan 22, 2021 at 01:06:22PM +0000, Manish Narani wrote:
>>>>>>Hi Michael,
>>>>>>>-----Original Message-----
>>>>>>>From: Michael Grzeschik <>
>>>>>>>Sent: Friday, January 22, 2021 1:39 PM
>>>>>>>To: Manish Narani <>
>>>>>>>;; Michal Simek
>>>>>>>git <>;; linux-arm-
>>>>>>>Subject: Re: [RESEND PATCH v3 2/2] usb: dwc3: Add driver for Xilinx
>>>>>>>On Mon, Jan 18, 2021 at 02:42:24PM +0100, Michael Grzeschik wrote:
>>>>>>>>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
>>>>>>>>>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
>>>>>>>>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,
>>>>>>>>If really the order of operations is limiting us, we probably need
>>>>>>>>another solution than this glue layer. Any Ideas?
>>>>>>>I found out what the difference between the Downstream and this
>>>>>>>Glue is. When using vanilla with this Glue code we may not set
>>>>>>>the following bit:
>>>>>>>>>+ /* Set PIPE Power Present signal in FPD Power Present
>>>>>>>>>+ writel(PIPE_POWER_ON, priv_data->regs +
>>>>>>>When I comment this out, the link stays stable. This is different in
>>>>>>>the Downstream Xilinx Kernel, where the bit is also set but has no
>>>>>>>negativ effect.
>>>>>>>Manish, can you give me a pointer what to look for?
>>>>>>>So setting this will also work with mainline?
>>>>>>I am looking further on this but from what I see here is that,
>>>>>>In order to make USB function properly, there are some dt changes
>>>needed in mainline for
>>>>>>USB node which include defining clocks coming from serdes.
>>>>>>The DT changes are pending to be sent to mainline.
>>>>>Can you push that state somewhere, so I could test it?
>>>>>Or is in the downstream kernel some things to copy?
>>>>>>Can you share the DT settings for USB node on your side?
>>>>>Here is my current configuration for the device node at usb0:
>>>>>zynqmp_reset: reset-controller {
>>>>> compatible = "xlnx,zynqmp-reset";
>>>>> #reset-cells = <1>;
>>>>>usb0: usb@ff9d0000 {
>>>>> #address-cells = <2>;
>>>>> #size-cells = <2>;
>>>>> status = "disabled";
>>>>> compatible = "xlnx,zynqmp-dwc3";
>>>>> reg = <0x0 0xff9d0000 0x0 0x100>;
>>>>> clock-names = "bus_clk", "ref_clk";
>>>>> power-domains = <&zynqmp_firmware PD_USB_0>;
>>>>> ranges;
>>>>> resets = <&zynqmp_reset ZYNQMP_RESET_USB0_CORERESET>,
>>>>> <&zynqmp_reset ZYNQMP_RESET_USB0_HIBERRESET>,
>>>>> <&zynqmp_reset ZYNQMP_RESET_USB0_APB>;
>>>>> reset-names = "usb_crst", "usb_hibrst", "usb_apbrst";
>>>>> phy-names = "usb3-phy";
>>>>> phys = <&psgtr 2 PHY_TYPE_USB3 0 2>;
>>>>> usb0_dwc3: dwc3@fe200000 {
>>>>> compatible = "snps,dwc3";
>>>>> interrupt-parent = <&gic>;
>>>>> interrupts = <0 65 4>;
>>>>> clock-names = "ref", "bus_early", "suspend";
>>>>> reg = <0x0 0xfe200000 0x0 0x40000>;
>>>>> };
>>>>>&usb0 {
>>>>> status = "okay";
>>>>> phy-names = "usb3-phy";
>>>>> phys = <&psgtr 2 PHY_TYPE_USB3 0 2>;
>>>>>&usb0_dwc3 {
>>>>> dr_mode = "peripheral";
>>>>> /* The following quirks are required, since the bInterval is 1 and we
>>>>> * handle steady ISOC streaming. See Usecase 3 in commit
>>>>> * ("usb: dwc3: gadget: Add support for disabling U1 and U2
>>>>> */
>>>>> snps,dis-u1-entry-quirk;
>>>>> snps,dis-u2-entry-quirk;
>>>>>>Meanwhile I will keep updating on the same.
>>>>>Thanks, that sounds great!
>>>>I have more feedback regarding this issues. As we saw new uncommon
>>>>effects, when using the glue. Regarding to get the plug/unplug behaviour
>>>>stable, we sticked with leaving out the setting of PIPE_POWER_ON in that
>>>>driver. Unfortunately, with that change, the dwc3 is not only not
>>>>sending any Erratic Errors any more, but also is lacking to send
>>>>disconnect interrupts.
>>>>Double checking with downstream shows that disconnects are working
>>>>completely fine in your downstream stack.
>>>>I think we should really need to know why PIPE_POWER_ON is making
>>>>a difference before we can say the dwc3 is stable with that glue.
>>>After bisecting your v5.4 and mainline we found out that this all is
>>>working fine, when setting "snps,dis_u3_susphy_quirk" in the zynqmp.dtsi
>>>dwc3 node.
>>>The code handling this quirk was introduced after v5.4, so this was
>>>never an issue with your downstream stack.
>>>"9ba3aca8 usb: dwc3: Disable phy suspend after power-on reset"
>>>We need to know if adding snps,dis_u3_susphy_quirk to the dwc nodes
>>>is generally necessary for zynqmp, so we can fix for everyone.
>>Yes, it is necessary for DWC3 on ZynqMP platform. This property should be
>>added to the DT node.
>For now this quirk does solve the issues regarding the pluging
>behaviour. But we would like to know why?
>Is the phy not properly configured/connected to serve the phy
>suspend as intended for the dwc3 stack? Is this a real Hardware issue,
>or does this quirk only disable the suspend behaviour even though it
>would work properly when configured correctly in software.
>The second question is addressing the dwc3 xilinx glue driver
>you are trying to mainline. We found that the driver is pulling and
>releasing some resets before and after changing the pll frequency
>comming from the reference clk lines. After that the undocumented
>according to the updated pll frequency. What do these bit change?
>Is this an internal configuration every dwc3 user on the zynqmp has
>to do or does this differ from user to user?
>Pengutronix e.K. | |
>Steuerwalder Str. 21 | |
>31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
>Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |

>linux-arm-kernel mailing list

Pengutronix e.K. | |
Steuerwalder Str. 21 | |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
[unhandled content-type:application/pgp-signature]
 \ /
  Last update: 2021-02-10 13:19    [W:6.453 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site