Hi Kishon, On Thu, Aug 29, 2019 at 7:10 AM Kishon Vijay Abraham I <kishon@xxxxxx> wrote: [...] > The PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION defines the Power > Sequencing and Reset Signal Timings in Table 2-4. Please also refer Figure > 2-10: Power Up of the CEM. > > ╔═════════════╤══════════════════════════════════════╤═════╤═════╤═══════╗ > ║ Symbol │ Parameter │ Min │ Max │ Units ║ > ╠═════════════╪══════════════════════════════════════╪═════╪═════╪═══════╣ > ║ T PVPERL │ Power stable to PERST# inactive │ 100 │ │ ms ║ > ╟─────────────┼──────────────────────────────────────┼─────┼─────┼───────╢ > ║ T PERST-CLK │ REFCLK stable before PERST# inactive │ 100 │ │ μs ║ > ╟─────────────┼──────────────────────────────────────┼─────┼─────┼───────╢ > ║ T PERST │ PERST# active time │ 100 │ │ μs ║ > ╟─────────────┼──────────────────────────────────────┼─────┼─────┼───────╢ > ║ T FAIL │ Power level invalid to PERST# active │ │ 500 │ ns ║ > ╟─────────────┼──────────────────────────────────────┼─────┼─────┼───────╢ > ║ T WKRF │ WAKE# rise – fall time │ │ 100 │ ns ║ > ╚═════════════╧══════════════════════════════════════╧═════╧═════╧═══════╝ > > In my code I used T PERST-CLK (i.e REFCLK stable before PERST# inactive). > REFCLK to the card is enabled as part of PHY enable and then wait for 100μs > before making PERST# inactive. > > Power to the device is given during board power up and the assumption here is > it will take more the 100ms for the probe to be invoked after board power up > (i.e after ROM, bootloaders and linux kernel). But if you have a regulator that > is enabled in PCI probe, then T PVPERL (100ms) should also used in probe. thank you for this detailed overview and for the explanation about the assumptions you made (and why) Martin
