Patch "usb: cdns3: fix race condition before setting doorbell" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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 the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     usb-cdns3-fix-race-condition-before-setting-doorbell.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit f5dc4ab56be0b62d6db9a401d67a250bd1a623e4
Author: Pawel Laszczak <pawell@xxxxxxxxxxx>
Date:   Tue Sep 7 08:26:19 2021 +0200

    usb: cdns3: fix race condition before setting doorbell
    
    [ Upstream commit b69ec50b3e55c4b2a85c8bc46763eaf330605847 ]
    
    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@xxxxxxxxxxxxxxx> # 5.12.x
    Tested-by: Aswath Govindraju <a-govindraju@xxxxxx>
    Reviewed-by: Aswath Govindraju <a-govindraju@xxxxxx>
    Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20210907062619.34622-1-pawell@xxxxxxxxxxxxxxxxxxxxx
    Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
index 9d38f864cb68..e11162294413 100644
--- a/drivers/usb/cdns3/gadget.c
+++ b/drivers/usb/cdns3/gadget.c
@@ -1101,6 +1101,19 @@ 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
@@ -1352,6 +1365,7 @@ 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));
 	}