Messages in this thread | | | Date | Thu, 24 Nov 2022 14:49:21 +0530 | From | Manivannan Sadhasivam <> | Subject | Re: [PATCH v13 1/2] PCI: endpoint: pci-epf-vntb: change doorbell register offset calc mathod |
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On Thu, Nov 24, 2022 at 12:50:35AM -0500, Frank Li wrote: > In drivers/ntb/hw/epf/ntb_hw_epf.c > ntb_epf_peer_db_set() > { > ... > db_offset = readl(ndev->ctrl_reg + NTB_EPF_DB_OFFSET(interrupt_num)); > writel(db_data, ndev->db_reg + (db_entry_size * interrupt_num) + > db_offset); > ... > } > > The door register offset's formular is > offset = db_entry_size * interrupt_num + db_offset[interrupt_number]
You did not mention the DB BAR here. Without that, this calculation doesn't make sense.
> > Previous db_entry_size is 4, all db_offset is 0.
s/Previous/Previously
> irq | offset > -------------- > 0 0 > 1 4 > 2 8 > ... > > Change to db_entry_size is 0 and db_offset is 0, 4, 8, ... > So we can get the same map value between irq and offset. This will be > convenience for hardware doorbell register memory map. >
In your irq-imx-mu-msi.c driver, the msi_address is calculated as:
``` u64 addr = msi_data->msiir_addr + 4 * data->hwirq; ```
So the MSI addresses itself are of 4 bytes width. So the offsets will be separated by 8 bytes like, 0, 8, 16,... and this won't match the MSI addresses as they are 4 bytes apart.
So you want to change the offset to 0, 4, 8,... by zeroing db_entry_size, right?
> Signed-off-by: Frank Li <Frank.Li@nxp.com> > --- > drivers/pci/endpoint/functions/pci-epf-vntb.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c > index 04698e7995a5..0d744975f815 100644 > --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c > +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c > @@ -461,11 +461,11 @@ static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb) > ctrl->num_mws = ntb->num_mws; > ntb->spad_size = spad_size; > > - ctrl->db_entry_size = sizeof(u32); > + ctrl->db_entry_size = 0; > > for (i = 0; i < ntb->db_count; i++) { > ntb->reg->db_data[i] = 1 + i; > - ntb->reg->db_offset[i] = 0; > + ntb->reg->db_offset[i] = sizeof(u32) * i;
If my above understanding is correct, then you could just reassign "db_entry_size" in epf_ntb_epc_msi_init().
Thanks, Mani
> } > > return 0; > -- > 2.34.1 >
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