Hi Krzysztof, On 27.06.2022 12:47, Krzysztof Kozlowski wrote: > On 27/06/2022 12:30, Marek Szyprowski wrote: >> On 24.06.2022 20:07, Krzysztof Kozlowski wrote: >>> On 24/06/2022 19:35, Bjorn Helgaas wrote: >>>> In exynos_pcie_host_init() [1], we call: >>>> >>>> phy_reset(ep->phy); >>>> phy_power_on(ep->phy); >>>> phy_init(ep->phy); >>>> >>>> The phy_init() function comment [2] says it must be called before >>>> phy_power_on(). Is exynos doing this backwards? >>> Looks like. I don't have Exynos hardware with a PCI, so cannot >>> test/fix/verify. >>> >>> Luckily for Exynos ;-) it's not alone in this pattern: >>> drivers/net/ethernet/marvell/sky2.c >>> drivers/usb/dwc2/platform.c >> I've checked that on the real hardware. Swapping the order of >> phy_power_on and phy_init breaks driver operation. >> >> However pci-exynos is the only driver that uses the phy-exynos-pcie, so >> we can simply swap the content of the init and power_on in the phy >> driver to adjust the code to the right order. power_on/init and >> exit/power_off are also called one after the other in pci-exynos, >> without any activity between them, so we can also simply move all >> operation to one pair of the callback, like power_on/off. >> >> Krzysztof, which solution would you prefer? > I think the real problem is that the Exynos PCIe phy init > (exynos5433_pcie_phy_init) performs parts of power on procedure, so the > code is mixed. Probably also the phy init could not happen earlier due > to gated clocks (ungated in exynos5433_pcie_phy_power_on). > > I would prefer to clean it up while ordering init+power_on, so figure > out more or less correct procedure. > > You can also look at Artpec-8 PHY - it seems using correct order > (init+reset): > https://lore.kernel.org/all/20220614011616epcms2p7dcaa67c53b7df5802dd7a697e2d472d7@epcms2p7/ I've played a bit with those register writes in exynos_pcie_phy and frankly speaking the currenly used (power_on + init) is the only sequence that works properly. I'm leaning to move everything to phy_init/exit. I really don't see how to split it into init + power_on callbacks. While touching this - I would also remove the phy_reset() call in the exynos-pcie driver. It is a left over from the old, obsoleted exynos5440 pcie code, not implemented in the current phy driver, also only a few drivers use or implement it. IMHO it doesn't make sense to keep such dead code. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
