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pci: tegra264: Do not toggle PRSNT# in tegra264_pcie_ep_rst_assert

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When EP boot up first and RP in power OFF state, default PERST# input is
high due to onboard pull up. When RP is powered ON, it causes a glitch
from high to low due to default pinctl settings, it is perceived as
PERST# assert by Endpoint. In tegra264_pcie_ep_rst_assert() PRNST#
signal is released (set high), this will cause PCIe link up failure.
This WAR is initially added for RP reboot case, to handle a scenario
where EP function driver still executing core_deinit as part of PERST#
assert and mean while RP boot up and ready for link up again. However
on Thor it is measured that core_deinit is taking only ~1.4 msec which
completes before RP boots. So, it is safe to remove PRNST# release WAR
in tegra264_pcie_ep_rst_assert(), this fixes link up failure when RP
boot after EP.

Bug 4981895

Change-Id: Ie24652a267bf3e3bc740d9c40e5b6d6671429b00
Signed-off-by: Srishti Goel <srgoel@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3345684
(cherry picked from commit 8944b4a4d767a144b7204865d26b4e989ee003b6)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3338072
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: Bitan Biswas <bbiswas@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>
This commit is contained in:
Srishti Goel
2025-04-10 10:49:45 +00:00
committed by Jon Hunter
parent 0138f99d46
commit 25d24fca15
1 changed files with 0 additions and 4 deletions
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4
drivers/pci/controller/pcie-tegra264-ep.c
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@@ -183,10 +183,6 @@ static void tegra264_pcie_ep_rst_assert(struct tegra264_pcie_ep *pcie)
if (pcie->ep_state == EP_STATE_DISABLED) if (pcie->ep_state == EP_STATE_DISABLED)
return; return;
/* Endpoint is going away, assert PRSNT# to mask EP from RP until it is ready link up */
if (pcie->pex_prsnt_gpiod)
gpiod_set_value_cansleep(pcie->pex_prsnt_gpiod, 0);
#if defined(NV_PCI_EPC_DEINIT_NOTIFY_PRESENT) /* Linux v6.11 */ #if defined(NV_PCI_EPC_DEINIT_NOTIFY_PRESENT) /* Linux v6.11 */
pci_epc_deinit_notify(pcie->epc); pci_epc_deinit_notify(pcie->epc);
#else #else