Commit b69ec50b authored by Pawel Laszczak's avatar Pawel Laszczak Committed by Greg Kroah-Hartman
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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: 7733f6c3 ("usb: cdns3: Add Cadence USB3 DRD Driver")
cc: <stable@vger.kernel.org> # 5.12.x
Tested-by: default avatarAswath Govindraju <a-govindraju@ti.com>
Reviewed-by: default avatarAswath Govindraju <a-govindraju@ti.com>
Signed-off-by: default avatarPawel Laszczak <pawell@cadence.com>
Link: https://lore.kernel.org/r/20210907062619.34622-1-pawell@gli-login.cadence.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 17956b53

drivers/usb/cdns3/cdns3-gadget.c

+14 −0
Original line number Diff line number Diff line
@@ -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));

	}