On Mon, Jan 18, 2021 at 05:24:38PM +0200, Felipe Balbi wrote:
Hi, Michael Grzeschik <mgr@xxxxxxxxxxxxxx> 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?
I already did that. In case the port is not working properly, the port was producing several "Erratic Errors" between the plug/unplug events. This was not the case until the reset_assert, pll configure, reset_deassert sequence was applied like in the downstream kernels phy driver on phy_init. Regards, Michael -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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