[U-Boot] [PATCH] FSL PCI: Configure PCIe reference ratio

[Joakim Tjernlund]

On Tue, 2017-11-21 at 17:32 +0000, York Sun wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> 
> 
> On 11/21/2017 09:29 AM, Joakim Tjernlund wrote:
> > On Tue, 2017-11-21 at 17:23 +0000, York Sun wrote:
> > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> > > 
> > > 
> > > On 11/21/2017 09:18 AM, Joakim Tjernlund wrote:
> > > > On Tue, 2017-09-12 at 19:56 +0200, Joakim Tjernlund wrote:
> > > > > Most FSL PCIe controllers expects 333 MHz PCI reference clock.
> > > > > This clock is derived from the CCB but in many cases the ref.
> > > > > clock is not 333 MHz and a divisor needs to be configured.
> > > > > 
> > > > > This adds PEX_CCB_DIV #define which can be defined for each
> > > > > type of CPU/platform.
> > > > > 
> > > > > Signed-off-by: Joakim Tjernlund <joakim.tjernlund at infinera.com>
> > > > > ---
> > > > >  drivers/pci/fsl_pci_init.c | 6 ++++++
> > > > >  1 file changed, 6 insertions(+)
> > > > > 
> > > > > diff --git a/drivers/pci/fsl_pci_init.c b/drivers/pci/fsl_pci_init.c
> > > > > index 52792dcd59..4d00b3f26c 100644
> > > > > --- a/drivers/pci/fsl_pci_init.c
> > > > > +++ b/drivers/pci/fsl_pci_init.c
> > > > > @@ -322,6 +322,12 @@ void fsl_pci_init(struct pci_controller *hose, struct fsl_pci_info *pci_info)
> > > > > 
> > > > >      pci_setup_indirect(hose, cfg_addr, cfg_data);
> > > > > 
> > > > > +#ifdef PEX_CCB_DIV
> > > > > +    /* Configure the PCIE controller core clock ratio */
> > > > > +    pci_hose_write_config_dword(hose, dev, 0x440,
> > > > > +                                ((gd->bus_clk / 1000000) *
> > > > > +                                 (16 / PEX_CCB_DIV)) / 333);
> > > > > +#endif
> > > > >      block_rev = in_be32(&pci->block_rev1);
> > > > >      if (PEX_IP_BLK_REV_2_2 <= block_rev) {
> > > > >              pi = &pci->pit[2];      /* 0xDC0 */
> > > > 
> > > > Ping?
> > > > 
> > > >  Jocke
> > > > 
> > > 
> > > I believe Mingkai's last comment was "to add the PCIe clock in gd".
> > 
> > Right, I seem to have forgotten to comment on that ...
> > Why add that complexity/bloat? This is a constant defined by the CPU/SOC so
> > it makes perfect sense to just #define it.
> > 
> 
> I am leaning to agree with you. The clock is either CCB clock, or CCB/2.
> Would it be better if you use a Kconfig option and select the divisor by
> SoC?

No, this is not something that needs Kconfig, just add the PEX_CCB_DIV #define
in relevant PPC CPU, like in config_mpc85xx.h 

 Jocke