Re: [PATCH v13 1/2] PCI: endpoint: pci-epf-vntb: change doorbell register offset calc mathod
From: Manivannan Sadhasivam <hidden>
Date: 2022-11-24 09:19:39
Also in:
imx, linux-devicetree, linux-pci, lkml
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?
quoted hunk ↗ jump to hunk
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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