On Wed, Aug 25, 2021 at 9:23 AM Baruch Siach [off-list ref] wrote:

Hi Rob,

On Wed, Aug 25 2021, Rob Herring wrote:

quoted

On Wed, Aug 25, 2021 at 6:25 AM Baruch Siach [off-list ref] wrote:

quoted

On Fri, Aug 06 2021, Rob Herring wrote:

quoted

On Wed, May 5, 2021 at 3:18 AM Baruch Siach [off-list ref] wrote:

quoted

+       writel(PCI_EXP_DEVCTL2_COMP_TMOUT_DIS, pci->dbi_base + offset +
+                       PCI_EXP_DEVCTL2);
+
+       writel(PCIE_CAP_CURR_DEEMPHASIS | SPEED_GEN3,
+                       pci->dbi_base + offset + PCI_EXP_DEVCTL2);

Doesn't this overwrite the prior register write?

It does. There are two mistakes here. The writel() above should set
PCIE20_DEVICE_CONTROL2_STATUS2 (offset 0x98).

No. Did you check what 'offset' is? PCIE20_DEVICE_CONTROL2_STATUS2 is
PCI_EXP_DEVCTL2 plus the status reg. What's wrong is it should be a
16-bit write.

Thanks for enlightening me. 'offset' is 0x70 here. So PCI_EXP_DEVCTL2 is
at 0x98, and PCI_EXP_LNKCTL2 is at 0xa0. Only the second writel() is
wrong. But since generic code handles speed, I can drop it entirely.

I see that dw_pcie_link_set_max_speed() uses dw_pcie_writel_dbi() to
write to PCI_EXP_LNKCTL2. Is that 16-bit write?

No, that may be because some platforms can only do 32-bit accesses and
dw_pcie_writew_dbi would be a RMW in that case. Or maybe there's some
reliance on clearing the status register.

Why are pci_regs.h register offsets in decimal?

No idea...

Rob