On Thu, Nov 07, 2024 at 08:39:43AM +0100, Lorenzo Bianconi wrote: > > On Wed, Nov 06, 2024 at 11:40:28PM +0100, Lorenzo Bianconi wrote: > > > > On Wed, Jul 03, 2024 at 06:12:44PM +0200, Lorenzo Bianconi wrote: > > > > > Introduce support for Airoha EN7581 PCIe controller to mediatek-gen3 > > > > > PCIe controller driver. > > > > > ... > > > > Is this where PERST# is asserted? If so, a comment to that effect > > > > would be helpful. Where is PERST# deasserted? Where are the required > > > > delays before deassert done? > > > > > > I can add a comment in en7581_pci_enable() describing the PERST issue for > > > EN7581. Please note we have a 250ms delay in en7581_pci_enable() after > > > configuring REG_PCI_CONTROL register. > > > > > > https://github.com/torvalds/linux/blob/master/drivers/clk/clk-en7523.c#L396 > > > > Does that 250ms delay correspond to a PCIe mandatory delay, e.g., > > something like PCIE_T_PVPERL_MS? I think it would be nice to have the > > required PCI delays in this driver if possible so it's easy to verify > > that they are all covered. > > IIRC I just used the delay value used in the vendor sdk. I do not > have a strong opinion about it but I guess if we move it in the > pcie-mediatek-gen3 driver, we will need to add it in each driver > where this clock is used. What do you think? I don't know what the 250ms delay is for. If it is for a required PCI delay, we should use the relevant standard #define for it, and it should be in the PCI controller driver. Otherwise it's impossible to verify that all the drivers are doing the correct delays. I don't know what other drivers are using that clock. Are you suggesting that it may be used in non-PCI situations where the required delay might be different? If another user requires 250ms, but PCI requires only 100ms, I think it would be worth having separate delays in each user so PCI wouldn't have to pay that extra 150ms. Bjorn
