RE: [PATCH] usb: chipidea: udc: make controller hardware endpoint primed
From: Piyush Mehta <hidden>
Date: 2021-09-13 09:49:34
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Hello Peter, Thanks for the review. Please find my inline comment with tag [Piyush]. Regards, Piyush Mehta -----Original Message----- From: Peter Chen <peter.chen@kernel.org> Sent: Sunday, September 12, 2021 1:11 PM To: Piyush Mehta <redacted> Cc: gregkh@linuxfoundation.org; linux-usb@vger.kernel.org; linux-kernel@vger.kernel.org; git <redacted>; Srinivas Goud <redacted>; Michal Simek <redacted> Subject: Re: [PATCH] usb: chipidea: udc: make controller hardware endpoint primed On 21-09-08 14:13:21, Piyush Mehta wrote:
quoted hunk ↗ jump to hunk
Root-cause: There is an issue like endpoint is not recognized as primed, when bus have more pressure and the add dTD tripwire semaphore (ATDTW bit in USBCMD register) that can cause the controller to ignore a dTD that is added to a primed endpoint. This issue observed with the Windows10 host machine. Workaround: The software must implement a periodic cycle, and check for each dTD, if the endpoint is primed. It can do this by reading the corresponding bits in the ENDPTPRIME and ENDPTSTAT registers. If these bits are read at 0, the software needs to re-prime the endpoint by writing 1 to the corresponding bit in the ENDPTPRIME register. Signed-off-by: Piyush Mehta <redacted> --- drivers/usb/chipidea/udc.c | 9 +++++++++ 1 file changed, 9 insertions(+)diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c index 8834ca6..d970f45 100644 --- a/drivers/usb/chipidea/udc.c +++ b/drivers/usb/chipidea/udc.c@@ -49,6 +49,8 @@ ctrl_endpt_in_desc = { .wMaxPacketSize = cpu_to_le16(CTRL_PAYLOAD_MAX), }; +static int reprime_dtd(struct ci_hdrc *ci, struct ci_hw_ep *hwep, + struct td_node *node); /** * hw_ep_bit: calculates the bit number * @num: endpoint number@@ -599,8 +601,15 @@ static int _hardware_enqueue(struct ci_hw_ep*hwep, struct ci_hw_req *hwreq) prevlastnode->ptr->next = cpu_to_le32(next); wmb(); + + if (ci->rev == CI_REVISION_22) { + if (!hw_read(ci, OP_ENDPTSTAT, BIT(n))) + reprime_dtd(ci, hwep, prevlastnode); + } +
Only for version 2.2? [Piyush] Yes, Xilinx chip-idea controller support revision 2.20 only. This solution is validated on revision 2.20 on the zynq7000 platform.
if (hw_read(ci, OP_ENDPTPRIME, BIT(n))) goto done; +
No blank line.
do {
hw_write(ci, OP_USBCMD, USBCMD_ATDTW, USBCMD_ATDTW);
tmp_stat = hw_read(ci, OP_ENDPTSTAT, BIT(n));
--
2.7.4-- Thanks, Peter Chen