[RFC] PCI: pci-imx6: Add delay to workaround kernel hang

[Tim Harvey]

On Fri, Jun 27, 2014 at 3:06 AM, Hong-Xing.Zhu at freescale.com
<Hong-Xing.Zhu at freescale.com> wrote:
> [Richard] I did the tests refer to this use-case, enable imx6 pcie on both u-boot and kernel,
> and I encounter the system hang too.
>
> Here are the latest updates and some clues from my side:
> - About 200us delay is required after the ltssm_en is set to be '1' at my side.
> Otherwise, system would be hang when driver access the pcie_phy_debug_r1 to check
> the link is up or not.
>
> - After that, system hang when rc trying to access the cfg space of ep device,
> Although the pcie link had been setup and I don't have know the root cause yet.
>
> - The kernel can boot up successfully, when I mask the cfg read/write call-back in pcie-designware.c
> Driver for debug purpose.
>
> Note:
> The sequence of the pcie initialization should be adjusted refer to the newly
>  discovered bug(pcie link maybe rarely random down after the system warm-reset).
> * Ref_ssp_en(bit16 of gpr1 register) should be set after the pcie others clks are enable.
> Enable pcie related clks --> delay for about ~10us waiting for the clks stable-->set ref_ssp_en(bit16 of gpr1 register).
>
> Debug is still on-going.
>

Any update on this? Are you or others at Freescale actively working on this?

Regards,

Tim