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xhci: tegra: Delay for disabling LFPS detector

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Occasionally, we are seeing some SuperSpeed devices resumes right after
being directed to U3. This commits add 500us delay to ensure LFPS
detector is disabled before sending ACK to firmware.

[   16.099363] tegra-xusb 70090000.usb: entering ELPG
[   16.104343] tegra-xusb 70090000.usb: 2-1 isn't suspended: 0x0c001203
[   16.114576] tegra-xusb 70090000.usb: not all ports suspended: -16
[   16.120789] tegra-xusb 70090000.usb: entering ELPG failed

The register write passes through a few flop stages of 32KHz clock domain.
NVIDIA ASIC designer reviewed RTL and suggests 500us delay.

Cc: stable@vger.kernel.org
Signed-off-by: JC Kuo <jckuo@nvidia.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20210115161907.2875631-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
JC Kuo 2021-01-15 18:19:07 +02:00 committed by Greg Kroah-Hartman
parent 576667bad3
commit da7e0c3c29
1 changed files with 7 additions and 0 deletions
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7
drivers/usb/host/xhci-tegra.c
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@ -623,6 +623,13 @@ static void tegra_xusb_mbox_handle(struct tegra_xusb *tegra,
enable);
if (err < 0)
break;
/*
* wait 500us for LFPS detector to be disabled before
* sending ACK
*/
if (!enable)
usleep_range(500, 1000);
}
if (err < 0) {