On Mon, Jan 22, 2024 at 09:24:33AM -0800, Matthew Gerlach wrote:
> Revision 2 of the Device Feature List (DFL) Port feature has
> slightly different requirements than revision 1. Revision 2
> does not need the port to reset at driver startup. In fact,
Please help illustrate what's the difference between Revision 1 & 2, and
why revision 2 needs not.
> performing a port reset during driver initialization can cause
> driver race conditions when the port is connected to a different
Please reorganize this part, in this description there seems be a
software racing bug and the patch is a workaround. But the fact is port
reset shouldn't been done for a new HW.
BTW: Is there a way to tell whether the port is connected to a different
PF? Any guarantee that revision 3, 4 ... would need a port reset or not?
Thanks,
Yilun
> PCIe Physical Function (PF) than the management PF performing
> the actual port reset.
>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> ---
> drivers/fpga/dfl-afu-main.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
> index c0a75ca360d6..7d7f80cd264f 100644
> --- a/drivers/fpga/dfl-afu-main.c
> +++ b/drivers/fpga/dfl-afu-main.c
> @@ -417,7 +417,18 @@ static const struct attribute_group port_hdr_group = {
> static int port_hdr_init(struct platform_device *pdev,
> struct dfl_feature *feature)
> {
> - port_reset(pdev);
> + void __iomem *base;
> + u8 rev;
> +
> + base = dfl_get_feature_ioaddr_by_id(&pdev->dev, PORT_FEATURE_ID_HEADER);
> +
> + rev = dfl_feature_revision(base);
> +
> + if (rev < 2)
> + port_reset(pdev);
> +
> + if (rev > 2)
> + dev_info(&pdev->dev, "unexpected port feature revision, %u\n", rev);
Remove the print. It is indicating an error but the function returns OK.
Thanks,
Yilun
>
> return 0;
> }
> --
> 2.34.1
>
>
