[U-Boot] setup of PEX_GCLK_RATIO in E500 CPUs(P2010) missing ?

[York Sun]

On 08/29/2017 06:21 AM, Joakim Tjernlund wrote:
> On Tue, 2017-08-29 at 12:47 +0200, Joakim Tjernlund wrote:
>> As we are looking at PCI stuff ATM I would like to ask
>> about PEX_GCLK_RATIO in E500 CPUs. I cannot find this is setup
>> at all for E500 but I THINK this is required.
>>
>> In 83xx one do:
>> get_clocks();
>> /* Configure the PCIE controller core clock ratio */
>> out_le32(hose_cfg_base + PEX_GCLK_RATIO,
> 
> A bit strange with out_le32 instead of out_be32 ?
> 
>> (((bus ? gd->arch.pciexp2_clk : gd->arch.pciexp1_clk)
>> / 1000000) * 16) / 333);
>> udelay(1000000);
>>
>> Any clues?
>>
>>   Jocke
> Seems like only 83xx is setting this parameter.
> 
> Anyhow, I put together this patch:
> 
> --- a/drivers/pci/fsl_pci_init.c
> +++ b/drivers/pci/fsl_pci_init.c
> @@ -322,6 +322,10 @@ void fsl_pci_init(struct pci_controller *hose, struct fsl_pci_info *pci_info)
>   
>          pci_setup_indirect(hose, cfg_addr, cfg_data);
>   
> +       /* Configure the PCIE controller core clock ratio */
> +       pci_hose_write_config_dword(hose, dev, 0x440, (gd->bus_clk / 333333333) * 16);
> +       /* udelay(1000000) needed here ?*/
> +
>          block_rev = in_be32(&pci->block_rev1);
>          if (PEX_IP_BLK_REV_2_2 <= block_rev) {
>                  pi = &pci->pit[2];      /* 0xDC0 */
> 
> Any chance this will work for all supported FSL PCIe controllers?
> 

Jocke,

You don't need to program this register if the actual PCIe clock is the 
same as default. Since SerDes reference clock has to be 100MHz for PCIe 
protocol, my guess is the PCIe clock is always correct. The bus_clk you 
are referring is not the PCIe clock. Again, I am not a PCIe expert, I 
could be wrong. Since PCIe (SerDes) has been working on multiple 
platforms, I guess the clock is correct.

York