diff options
| author | Siddharth Vadapalli <s-vadapalli@ti.com> | 2024-11-04 13:14:20 +0530 |
|---|---|---|
| committer | Krzysztof Wilczyński <kwilczynski@kernel.org> | 2024-11-04 12:43:36 +0000 |
| commit | 22a9120479a40a56c13c5e473a0100fad2e017c0 (patch) | |
| tree | e2b08ffd3dd7c131705b4a543574f130224501fb | |
| parent | 08e835268c35e851b308f326357224248cfb445b (diff) | |
| download | lwn-22a9120479a40a56c13c5e473a0100fad2e017c0.tar.gz lwn-22a9120479a40a56c13c5e473a0100fad2e017c0.zip | |
PCI: j721e: Deassert PERST# after a delay of PCIE_T_PVPERL_MS milliseconds
According to Section 2.2 of the PCI Express Card Electromechanical
Specification (Revision 5.1), in order to ensure that the power and the
reference clock are stable, PERST# has to be deasserted after a delay of
100 milliseconds (TPVPERL).
Currently, it is being assumed that the power is already stable, which
is not necessarily true.
Hence, change the delay to PCIE_T_PVPERL_MS to guarantee that power and
reference clock are stable.
Fixes: f3e25911a430 ("PCI: j721e: Add TI J721E PCIe driver")
Fixes: f96b69713733 ("PCI: j721e: Use T_PERST_CLK_US macro")
Link: https://lore.kernel.org/r/20241104074420.1862932-1-s-vadapalli@ti.com
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
| -rw-r--r-- | drivers/pci/controller/cadence/pci-j721e.c | 26 |
1 files changed, 12 insertions, 14 deletions
diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c index c9f3103d68e1..dc10d51c1352 100644 --- a/drivers/pci/controller/cadence/pci-j721e.c +++ b/drivers/pci/controller/cadence/pci-j721e.c @@ -583,15 +583,14 @@ static int j721e_pcie_probe(struct platform_device *pdev) pcie->refclk = clk; /* - * The "Power Sequencing and Reset Signal Timings" table of the - * PCI Express Card Electromechanical Specification, Revision - * 5.1, Section 2.9.2, Symbol "T_PERST-CLK", indicates PERST# - * should be deasserted after minimum of 100us once REFCLK is - * stable. The REFCLK to the connector in RC mode is selected - * while enabling the PHY. So deassert PERST# after 100 us. + * Section 2.2 of the PCI Express Card Electromechanical + * Specification (Revision 5.1) mandates that the deassertion + * of the PERST# signal should be delayed by 100 ms (TPVPERL). + * This shall ensure that the power and the reference clock + * are stable. */ if (gpiod) { - fsleep(PCIE_T_PERST_CLK_US); + msleep(PCIE_T_PVPERL_MS); gpiod_set_value_cansleep(gpiod, 1); } @@ -682,15 +681,14 @@ static int j721e_pcie_resume_noirq(struct device *dev) return ret; /* - * The "Power Sequencing and Reset Signal Timings" table of the - * PCI Express Card Electromechanical Specification, Revision - * 5.1, Section 2.9.2, Symbol "T_PERST-CLK", indicates PERST# - * should be deasserted after minimum of 100us once REFCLK is - * stable. The REFCLK to the connector in RC mode is selected - * while enabling the PHY. So deassert PERST# after 100 us. + * Section 2.2 of the PCI Express Card Electromechanical + * Specification (Revision 5.1) mandates that the deassertion + * of the PERST# signal should be delayed by 100 ms (TPVPERL). + * This shall ensure that the power and the reference clock + * are stable. */ if (pcie->reset_gpio) { - fsleep(PCIE_T_PERST_CLK_US); + msleep(PCIE_T_PVPERL_MS); gpiod_set_value_cansleep(pcie->reset_gpio, 1); } |