Re: [PATCH V2 16/28] PCI: tegra: Set target speed as Gen1 before starting LTSSM

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On Tue, Apr 23, 2019 at 02:58:13PM +0530, Manikanta Maddireddy wrote:
> PCIe link up fails with few legacy endpoints if root port advertises both
> Gen-1 and Gen-2 speeds in Tegra. This is because link number negotiation
> fails if both Gen1 & Gen2 are advertised. Tegra doesn't retry link up by
> advertising only Gen1. Hence, the strategy followed here is to initially
> advertise only Gen-1 and after link is up, retrain link to Gen-2 speed.
> 
> Tegra doesn't support HW autonomous speed change. Link comes up in Gen1
> even if Gen2 is advertised, so there is no downside of this change.
> 
> This behavior is observed with following two PCIe devices on Tegra,
>  - Fusion HDTV 5 Express card
>  - IOGear SIL - PCIE - SATA card
> 
> Signed-off-by: Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>
> ---
> V2: Updated commit log to reflect why this issue is observed on Tegra with
> these particular cards
> 
>  drivers/pci/controller/pci-tegra.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)

Acked-by: Thierry Reding <treding@xxxxxxxxxx>

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