On Thu, 30 Apr 2020 10:06:17 +0200, =?UTF-8?q?Pali=20Roh=C3=A1r?= wrote: > From: Marek Behún <marek.behun@xxxxxx> > > Currently the aardvark driver trains link in PCIe gen2 mode. This may > cause some buggy gen1 cards (such as Compex WLE900VX) to be unstable or > even not detected. Moreover when ASPM code tries to retrain link second > time, these cards may stop responding and link goes down. If gen1 is > used this does not happen. > > Unconditionally forcing gen1 is not a good solution since it may have > performance impact on gen2 cards. > > To overcome this, read 'max-link-speed' property (as defined in PCI > device tree bindings) and use this as max gen mode. Then iteratively try > link training at this mode or lower until successful. After successful > link training choose final controller gen based on Negotiated Link Speed > from Link Status register, which should match card speed. > > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> > Signed-off-by: Marek Behún <marek.behun@xxxxxx> > --- > drivers/pci/controller/pci-aardvark.c | 114 ++++++++++++++++++++------ > 1 file changed, 89 insertions(+), 25 deletions(-) > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
