[PATCH v4 5/7] PCI: spacemit: introduce SpacemiT PCIe host driver

[Alex Elder]

On 10/31/25 5:31 PM, Aurelien Jarno wrote:
> Hi Alex,
> 
> On 2025-10-30 17:02, Alex Elder wrote:
>> +/* Disable ASPM L1 for now, until reported errors can be reproduced */
> 
> Thanks for adding this function.
> 
>> +static void k1_pcie_post_init(struct dw_pcie_rp *pp)
>> +{
>> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> +	u8 offset;
>> +	u32 val;
>> +
>> +	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
>> +
>> +	dw_pcie_dbi_ro_wr_en(pci);
>> +
>> +	/* Turn off ASPM L1 for the link */
>> +	val = readl(pci->dbi_base + offset + PCI_EXP_LNKCAP);
> 
> Why not using dw_pcie_readl_dbi() instead?
> 
>> +	val &= ~PCI_EXP_LNKCAP_ASPM_L1;
>> +	writel(val, pci->dbi_base + offset + PCI_EXP_LNKCAP);
> 
> And here dw_pcie_writel_dbi()?
> 
>> +
>> +	dw_pcie_dbi_ro_wr_dis(pci);
>> +}
>> +
>> +static void k1_pcie_deinit(struct dw_pcie_rp *pp)
>> +{
>> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> +	struct k1_pcie *k1 = to_k1_pcie(pci);
>> +
>> +	/* Assert fundamental reset (drive PERST# low) */
>> +	regmap_set_bits(k1->pmu, k1->pmu_off + PCIE_CLK_RESET_CONTROL,
>> +			PCIE_RC_PERST);
>> +
>> +	phy_exit(k1->phy);
>> +
>> +	k1_pcie_disable_resources(k1);
>> +}
>> +
>> +static const struct dw_pcie_host_ops k1_pcie_host_ops = {
>> +	.init		= k1_pcie_init,
>> +	.post_init	= k1_pcie_post_init,
> 
> Unfortunately, while I can see the effect of the change with for
> instance lspci -vvv, this happens way too late in the device scan
> process, i.e. after pcie_aspm_override_default_link_state() and causes
> L1 to still be enabled.

OK thanks for this information.  I am going to contact you
privately to get more information on your errors (and those
Johannes is reporting) so that I can try to resolve them
before I post the next version of this patch series.

					-Alex

> 
> I have tried to move it earlier, in k1_pcie_init() after writing the
> vendor and device IDs. This works as long as "nvme scan" is run in
> U-Boot. But if I don't run this command, it seems that the change is
> ignored or lost (i.e. I can still see L1 enabled with lspci -vvv).
> 
> Moving it at the end of k1_pcie_init() works fine, like moving it at the
> beginning of k1_pcie_start_link(). But my knowledge is too limited to
> know where is the correct place.
> 
> Regards
> Aurelien
>