[PATCH v2] phy: freescale: imx8m-pcie: fix pcie link-up instability

[Vinod Koul]

On 27-03-24, 08:19, Marcel Ziswiler wrote:
> From: Marcel Ziswiler <marcel.ziswiler at toradex.com>
> 
> On the i.MX 8M Mini, the AUX_PLL_REFCLK_SEL has to be left at its reset
> default of AUX_IN (PLL clock).
> 
> Background Information:
> In our automated testing setup, we use Delock Mini-PCIe SATA cards [1].
> While this setup has proven very stable overall we noticed upstream on
> the i.MX 8M Mini fails quite regularly (about 50/50) to bring up the
> PCIe link while with NXP's downstream BSP 5.15.71_2.2.2 it always works.
> As that old downstream stuff was quite different, I first also tried
> NXP's latest downstream BSP 6.1.55_2.2.0 which from a PCIe point of view
> is fairly vanilla, however, also there the PCIe link-up was not stable.
> Comparing and debugging I noticed that upstream explicitly configures
> the AUX_PLL_REFCLK_SEL to I_PLL_REFCLK_FROM_SYSPLL while working
> downstream [2] leaving it at reset defaults of AUX_IN (PLL clock).
> Unfortunately, the TRM does not mention any further details about this
> register (both for the i.MX 8M Mini as well as the Plus).
> NXP confirmed their validation codes for the i.MX8MM PCIe doesn't
> configure cmn_reg063 (offset: 0x18C).
> BTW: On the i.MX 8M Plus we have not seen any issues with PCIe with the
> exact same setup which is why I left it unchanged.

This does not apply on phy/fixes, pls rebase

-- 
~Vinod