[PATCH] PCI: fu740: RFC: force gen1 and get devices probing
Ben Dooks
ben.dooks at codethink.co.uk
Sat Feb 5 00:59:13 PST 2022
On 2022-02-04 19:12, David Abdurachmanov wrote:
> On Fri, Feb 4, 2022 at 8:35 PM Ben Dooks <ben.dooks at codethink.co.uk>
> wrote:
>>
>> The dw pcie core does not probe devices unless this fix
>> from u-boot is applied. The link must be changed to gen1
>> and then the system will see all the other pcie devices
>> behind the unmatched board's bridge.
>>
>> This is a quick PoC to try and get our test farm working
>> when a system does not have the pcie initialised by a
>> u-boot script.
>>
>> I will look at a proper patch when I am back in the office
>
> Hi,
>
> Have you looked into the patches posted for Linux and U-Boot from
> Maciej W. Rozycki?
I haven't seen any u-boot patches, but I do know u-boot has been
able to do this since 2021.08 release as a colleague has apparently
know about needing to initialise PCIe under u-boot to get Linux to
properly enumerate devices.
Do you have a reference to these, trivial google searches did not
show any patches.
> On the Linux side (not reviewed yet):
> [PATCH v3] pci: Work around ASMedia ASM2824 PCIe link training failures
> https://www.spinics.net/lists/linux-pci/msg120112.html
This is not the issue, we do not see even the ASMedia PCIe bridge
if u-boot does not have PCIe initialisation done.
> The U-Boot fix was merged a few days ago.
Ok, but I think the kernel should also have this fix done as it
seems bad to have to upgrade u-boot on all the machines for
something that is not a large fix.
> david
>
>> ---
>> drivers/pci/controller/dwc/pcie-fu740.c | 37
>> +++++++++++++++++++++++++
>> 1 file changed, 37 insertions(+)
>>
>> diff --git a/drivers/pci/controller/dwc/pcie-fu740.c
>> b/drivers/pci/controller/dwc/pcie-fu740.c
>> index 960e58ead5f2..44f792764e45 100644
>> --- a/drivers/pci/controller/dwc/pcie-fu740.c
>> +++ b/drivers/pci/controller/dwc/pcie-fu740.c
>> @@ -181,11 +181,48 @@ static void fu740_pcie_init_phy(struct
>> fu740_pcie *afp)
>> fu740_phyregwrite(1, PCIEX8MGMT_PHY_LANE3_BASE,
>> PCIEX8MGMT_PHY_INIT_VAL, afp);
>> }
>>
>> +/* u-boot forces system to gen1 otherwise nothing probes... */
>> +static void pcie_sifive_force_gen1(struct dw_pcie *dw, struct
>> fu740_pcie *afp )
>> +{
>> + unsigned val;
>> +
>> +#if 0
>> + /* u-boot code */
>> + /* ctrl_ro_wr_enable */
>> + val = readl(sv->dw.dbi_base + PCIE_MISC_CONTROL_1);
>> + val |= DBI_RO_WR_EN;
>> + writel(val, sv->dw.dbi_base + PCIE_MISC_CONTROL_1);
>> +
>> + /* configure link cap */
>> + linkcap = readl(sv->dw.dbi_base + PF0_PCIE_CAP_LINK_CAP);
>> + linkcap |= PCIE_LINK_CAP_MAX_SPEED_MASK;
>> + writel(linkcap, sv->dw.dbi_base + PF0_PCIE_CAP_LINK_CAP);
>> +
>> + /* ctrl_ro_wr_disable */
>> + val &= ~DBI_RO_WR_EN;
>> + writel(val, sv->dw.dbi_base + PCIE_MISC_CONTROL_1);
>> +#endif
>> +
>> + val = readl_relaxed(dw->dbi_base + PCIE_MISC_CONTROL_1_OFF);
>> + val |= PCIE_DBI_RO_WR_EN;
>> + writel_relaxed(val, dw->dbi_base + PCIE_MISC_CONTROL_1_OFF);
I've found pre-made functions for these.
>> +
>> + val = readl(dw->dbi_base + 0x70 + 0x0c);
>> + val |= 0xf;
>> + writel(val, dw->dbi_base + 0x70 + 0x0c);
Will fix to config-register 0x0c and try and find the relevant macros
for this and the proper accessor macros for the dw driver.
>> +
>> + val = readl_relaxed(dw->dbi_base + PCIE_MISC_CONTROL_1_OFF);
>> + val &= ~PCIE_DBI_RO_WR_EN;
>> + writel_relaxed(val, dw->dbi_base + PCIE_MISC_CONTROL_1_OFF);
>> +}
>> +
>> static int fu740_pcie_start_link(struct dw_pcie *pci)
>> {
>> struct device *dev = pci->dev;
>> struct fu740_pcie *afp = dev_get_drvdata(dev);
>>
>> + pcie_sifive_force_gen1(pci, afp);
I'll change this to fu740_pcie_force_gen1()
>> +
>> /* Enable LTSSM */
>> writel_relaxed(0x1, afp->mgmt_base +
>> PCIEX8MGMT_APP_LTSSM_ENABLE);
>> return 0;
>> --
>> 2.34.1
>>
>>
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