For Foxconn T99W175 device(sdx55 platform) in some host platform,
it would be unavailable once the host execute the err handler.

After checking, it's caused by the delay time too short to
get a successful reset.

Please see my test evidence as bewlow(BTW, I add some extra test logs
in function mhi_pci_reset_prepare and mhi_pci_reset_done):
  When MHI_POST_RESET_DELAY_MS equals to 500ms:
   Nov  4 14:30:03 jbd-ThinkEdge kernel: [  146.222477] mhi mhi0: Device MHI is not in valid state
   Nov  4 14:30:03 jbd-ThinkEdge kernel: [  146.222628] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_prepare reset
   Nov  4 14:30:03 jbd-ThinkEdge kernel: [  146.222631] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_prepare mhi_soc_reset
   Nov  4 14:30:03 jbd-ThinkEdge kernel: [  146.222632] mhi mhi0:  mhi_soc_reset write soc to reset
   Nov  4 14:30:05 jbd-ThinkEdge kernel: [  147.839993] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_done
   Nov  4 14:30:05 jbd-ThinkEdge kernel: [  147.902063] mhi-pci-generic 0000:2d:00.0: reset failed

  When MHI_POST_RESET_DELAY_MS equals to 1000ms or 1500ms:
   Nov  4 19:07:26 jbd-ThinkEdge kernel: [  157.067857] mhi mhi0: Device MHI is not in valid state
   Nov  4 19:07:26 jbd-ThinkEdge kernel: [  157.068029] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_prepare reset
   Nov  4 19:07:26 jbd-ThinkEdge kernel: [  157.068032] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_prepare mhi_soc_reset
   Nov  4 19:07:26 jbd-ThinkEdge kernel: [  157.068034] mhi mhi0:  mhi_soc_reset write soc to reset
   Nov  4 19:07:29 jbd-ThinkEdge kernel: [  159.607006] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_done
   Nov  4 19:07:29 jbd-ThinkEdge kernel: [  159.607152] mhi mhi0: Requested to power ON
   Nov  4 19:07:51 jbd-ThinkEdge kernel: [  181.302872] mhi mhi0: Failed to reset MHI due to syserr state
   Nov  4 19:07:51 jbd-ThinkEdge kernel: [  181.303011] mhi-pci-generic 0000:2d:00.0: failed to power up MHI controller

  When MHI_POST_RESET_DELAY_MS equals to 2000ms:
   Nov  4 17:51:08 jbd-ThinkEdge kernel: [  147.180527] mhi mhi0: Failed to transition from PM state: Linkdown or Error Fatal Detect to: SYS ERROR Process
   Nov  4 17:51:08 jbd-ThinkEdge kernel: [  147.180535] mhi mhi0: Device MHI is not in valid state
   Nov  4 17:51:08 jbd-ThinkEdge kernel: [  147.180722] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_prepare reset
   Nov  4 17:51:08 jbd-ThinkEdge kernel: [  147.180725] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_prepare mhi_soc_reset
   Nov  4 17:51:08 jbd-ThinkEdge kernel: [  147.180727] mhi mhi0:  mhi_soc_reset write soc to reset
   Nov  4 17:51:11 jbd-ThinkEdge kernel: [  150.230787] mhi-pci-generic 0000:2d:00.0: mhi_pci_reset_done
   Nov  4 17:51:11 jbd-ThinkEdge kernel: [  150.230928] mhi mhi0: Requested to power ON
   Nov  4 17:51:11 jbd-ThinkEdge kernel: [  150.231173] mhi mhi0: Power on setup success
   Nov  4 17:51:14 jbd-ThinkEdge kernel: [  153.254747] mhi mhi0: Wait for device to enter SBL or Mission mode

I also tried big data like 3000, and it worked as well. 500ms may not be
enough for all support mhi device. We shall increase it to 2000ms
at least.

Link: https://lore.kernel.org/r/20211108113127.3938-1-slark_xiao@163.com
[mani: massaged commit message little bit, added Fixes tag and CCed stable]
Fixes: 8ccc3279 ("mhi: pci_generic: Add support for reset")
Cc: stable@vger.kernel.org
Reviewed-by: NManivannan Sadhasivam <mani@kernel.org>
Signed-off-by: NSlark Xiao <slark_xiao@163.com>
Signed-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20211126104951.35685-2-manivannan.sadhasivam@linaro.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>