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PCI: Add PCIE_RESET_CONFIG_DEVICE_WAIT_MS waiting time value

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Add the PCIE_RESET_CONFIG_DEVICE_WAIT_MS macro to define the minimum
waiting time between exit from a conventional reset and sending the
first configuration request to the device.

As described in PCIe r6.0, sec 6.6.1 <Conventional Reset>, there are two
different use cases of the value:

   - "With a Downstream Port that does not support Link speeds greater
     than 5.0 GT/s, software must wait a minimum of 100 ms following exit
     from a Conventional Reset before sending a Configuration Request to
     the device immediately below that Port."

   - "With a Downstream Port that supports Link speeds greater than
     5.0 GT/s, software must wait a minimum of 100 ms after Link training
     completes before sending a Configuration Request to the device
     immediately below that Port."

[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/20240328091835.14797-21-minda.chen@starfivetech.com
Signed-off-by: Kevin Xie <kevin.xie@starfivetech.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
This commit is contained in:
Kevin Xie 2024-03-28 17:18:33 +08:00 committed by Bjorn Helgaas
parent d76ef0531c
commit d5ceb9496c
1 changed files with 15 additions and 0 deletions
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15
drivers/pci/pci.h
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@ -22,6 +22,21 @@
*/
#define PCIE_PME_TO_L2_TIMEOUT_US 10000
/*
* PCIe r6.0, sec 6.6.1 <Conventional Reset>
*
* - "With a Downstream Port that does not support Link speeds greater
* than 5.0 GT/s, software must wait a minimum of 100 ms following exit
* from a Conventional Reset before sending a Configuration Request to
* the device immediately below that Port."
*
* - "With a Downstream Port that supports Link speeds greater than
* 5.0 GT/s, software must wait a minimum of 100 ms after Link training
* completes before sending a Configuration Request to the device
* immediately below that Port."
*/
#define PCIE_RESET_CONFIG_DEVICE_WAIT_MS 100
extern const unsigned char pcie_link_speed[];
extern bool pci_early_dump;