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usb: cdns3: fix race condition before setting doorbell

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[ 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: 7733f6c32e ("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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Pawel Laszczak 2021-09-07 08:26:19 +02:00 committed by Greg Kroah-Hartman
parent 3945c48136
commit 23115ca7d2
1 changed files with 14 additions and 0 deletions
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14
drivers/usb/cdns3/gadget.c
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@ -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));
}