From mboxrd@z Thu Jan 1 00:00:00 1970 From: York Sun Date: Tue, 29 Aug 2017 17:33:32 +0000 Subject: [U-Boot] setup of PEX_GCLK_RATIO in E500 CPUs(P2010) missing ? References: <1504003621.4350.49.camel@infinera.com> <1504012881.32677.3.camel@infinera.com> <1504026376.32677.11.camel@infinera.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de +Roy Zang to comment on PCIe clock source On 08/29/2017 10:06 AM, Joakim Tjernlund wrote: > On Tue, 2017-08-29 at 15:43 +0000, York Sun wrote: >> 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. > > I don't think so. Here is what T1042 says about this: > > The PCI Express controller clock frequency is one-half the platform clock frequency. > > The PCI Express controller core clock ratio register is used to program the ratio of the > actual PCI Express controller clock frequency to the default controller core frequency > ( 333 MHz ). This is required only when a PCI Express controller clock frequency other > than the default 333 MHz has to be used. > As an example of programming PEX_GCLK_RATIO, consider the case where the actual > PCI Express controller clock is 250 MHz, the ratio of the actual clock to the default clock > ( 333 MHz) is 3:4. that is, the default core clock has to be multiplied by the ratio (3/4, > which is equivalent to 12/16). So the register has to be programmed with the decimal > numerator value 12 or 0x0000_000C. > > Our CCB is 250 MHz so this should be set to 0xc. > > I found this on Google too: > The PEX controller hardware requires for timing tuning in order to operate properly at given CCB/2 clock > frequency. PEX_GCLK_RATIO register controls this tuning with 333MHz/16 granularities. So for given CCB > frequency Fccb [MHz] we must write to PEX_GCLK_RATIO nearest integer of ((Fccb/2)/(333/16)). So for Fccb=375 > we have to write 18. Jocke, Basically I agree with you, if the clock is different from default, you need to set the ratio. T104x indeed uses 1/2 platform clock as PCIe clock. I am not sure if P2010 uses the same way. Let me add Roy to this thread. Roy, how do we get PCIe clock for P1/T1 (and other mpc85xx) SoCs? Don't we need to set PEX_GCLK_RATIO register? It is not even in the header file. York