On Sun, Nov 13, 2016 at 10:11 PM, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> wrote: > Rockchip's RC outputs 100MHz reference clock but there are > two methods for PHY to generate it. > > (1)One of them is to use system PLL to generate 100MHz clock and > the PHY will relock it and filter signal noise then outputs the > reference clock. > > (2)Another way is to share Soc's 24MHZ crystal oscillator with > PHY and force PHY's DLL to generate 100MHz internally. > > When using case(2), the exit from L0s doesn't work fine occasionally > due to the broken design of RC receiver's logical circuit. So even if > we use extended-synch, it still fails for PHY to relock the bits from > FTS sometimes. This will hang the system. > > Maybe we could argue that why not use case(1) to avoid it? The reason > is that as we could see the reference clock is derived from system PLL > and the path from it to PHY isn't so clean which means there are some > noise introduced by power-domain and other buses can't be filterd out > by PHY and we could see noise from the frequency spectrum by oscilloscope. > This makes the TX compatibility test a little difficult to pass the spec. > So case(1) and case(2) are both used indeed now. If using case(2), we > should disable RC's L0s support, and that is why we need this property to > indicate this quirk. > > Also after checking quirk.c, I noticed there is already a quirk for > disabling L0s unconditionally, quirk_disable_aspm_l0s. But obviously we > shouldn't do that as mentioned above that case(1) could still works fine > with L0s. > > Reported-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx> > Cc: Brian Norris <briannorris@xxxxxxxxxxxx> > Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> > > --- > > Documentation/devicetree/bindings/pci/rockchip-pcie.txt | 2 ++ > drivers/pci/host/pcie-rockchip.c | 9 +++++++++ > 2 files changed, 11 insertions(+) > > diff --git a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt > index ba67b39..cfa44a7 100644 > --- a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt > +++ b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt > @@ -42,6 +42,8 @@ Required properties: > Optional Property: > - ep-gpios: contain the entry for pre-reset gpio > - num-lanes: number of lanes to use > +- quirk,aspm-no-l0s: RC won't support ASPM L0s. This property is needed if quirk is not a vendor. Drop it. > + using 24MHz OSC for RC's PHY. > - vpcie3v3-supply: The phandle to the 3.3v regulator to use for PCIe. > - vpcie1v8-supply: The phandle to the 1.8v regulator to use for PCIe. > - vpcie0v9-supply: The phandle to the 0.9v regulator to use for PCIe. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
