This is a note to let you know that I've just added the patch titled
usb: cdns3: fix race condition before setting doorbell
to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From b69ec50b3e55c4b2a85c8bc46763eaf330605847 Mon Sep 17 00:00:00 2001
From: Pawel Laszczak pawell@cadence.com Date: Tue, 7 Sep 2021 08:26:19 +0200 Subject: usb: cdns3: fix race condition before setting doorbell
For DEV_VER_V3 version there exist race condition between clearing ep_sts.EP_STS_TRBERR and setting ep_cmd.EP_CMD_DRDY bit. Setting EP_CMD_DRDY will be ignored by controller when EP_STS_TRBERR is set. So, between these two instructions we have a small time gap in which the EP_STSS_TRBERR can be set. In such case the transfer will not start after setting doorbell.
Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver") cc: stable@vger.kernel.org # 5.12.x Tested-by: Aswath Govindraju a-govindraju@ti.com Reviewed-by: Aswath Govindraju a-govindraju@ti.com Signed-off-by: Pawel Laszczak pawell@cadence.com Link: https://lore.kernel.org/r/20210907062619.34622-1-pawell@gli-login.cadence.co... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/cdns3/cdns3-gadget.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c index 5d8c982019af..1f3b4a142212 100644 --- a/drivers/usb/cdns3/cdns3-gadget.c +++ b/drivers/usb/cdns3/cdns3-gadget.c @@ -1100,6 +1100,19 @@ static int cdns3_ep_run_stream_transfer(struct cdns3_endpoint *priv_ep, return 0; }
+static void cdns3_rearm_drdy_if_needed(struct cdns3_endpoint *priv_ep) +{ + struct cdns3_device *priv_dev = priv_ep->cdns3_dev; + + if (priv_dev->dev_ver < DEV_VER_V3) + return; + + if (readl(&priv_dev->regs->ep_sts) & EP_STS_TRBERR) { + writel(EP_STS_TRBERR, &priv_dev->regs->ep_sts); + writel(EP_CMD_DRDY, &priv_dev->regs->ep_cmd); + } +} + /** * cdns3_ep_run_transfer - start transfer on no-default endpoint hardware * @priv_ep: endpoint object @@ -1351,6 +1364,7 @@ static int cdns3_ep_run_transfer(struct cdns3_endpoint *priv_ep, /*clearing TRBERR and EP_STS_DESCMIS before seting DRDY*/ writel(EP_STS_TRBERR | EP_STS_DESCMIS, &priv_dev->regs->ep_sts); writel(EP_CMD_DRDY, &priv_dev->regs->ep_cmd); + cdns3_rearm_drdy_if_needed(priv_ep); trace_cdns3_doorbell_epx(priv_ep->name, readl(&priv_dev->regs->ep_traddr)); }