Re: [PATCH v1 2/7] fpga: dfl: check feature type before parse irq info

Tom Rix
2022-02-15T14:51:35Z

On 2/14/22 3:26 AM, Tianfei zhang wrote:
> From: Tianfei Zhang <tianfei.zhang@intel.com>
>
> The feature ID of "Port User Interrupt" and the
> "PMCI Subsystem" are identical, 0x12, but one is for FME,
> other is for Port. It should check the feature type While
> parsing the irq info in parse_feature_irqs().

This seems like a bug fix and not part of iofs feature.

Split this out of the patchset.

This is a workaround a hardware problem, there should be some comments
to the effect that you can't trust _this_ or _that_ feature id and some
special handling earlier.

The ambiguity of feature id is a problem, and this sort of bug will
happen again.

What can be done to prevent this in the future ?

>
> Signed-off-by: Tianfei Zhang <tianfei.zhang@intel.com>
> ---
> drivers/fpga/dfl.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 599bb21d86af..26f8cf890700 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -940,9 +940,14 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
> {
> void __iomem *base = binfo->ioaddr + ofst;
> unsigned int i, ibase, inr = 0;
> + enum dfl_id_type type;
> int virq;
> u64 v;
>
> + type = feature_dev_id_type(binfo->feature_dev);
> + if (type >= DFL_ID_MAX)
> + return -EINVAL;
> +
> /*
> * Ideally DFL framework should only read info from DFL header, but
> * current version DFL only provides mmio resources information for
> @@ -959,16 +964,22 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
> */
> switch (fid) {
> case PORT_FEATURE_ID_UINT:
> + if (type != PORT_ID)
> + break;

Instead of embedding a break in the switch, break the switch into fme
switch and port switch

if (type == PORT_ID)

port-switch

else if (type == FME_ID

fme-switch

Tom

> v = readq(base + PORT_UINT_CAP);
> ibase = FIELD_GET(PORT_UINT_CAP_FST_VECT, v);
> inr = FIELD_GET(PORT_UINT_CAP_INT_NUM, v);
> break;
> case PORT_FEATURE_ID_ERROR:
> + if (type != PORT_ID)
> + break;
> v = readq(base + PORT_ERROR_CAP);
> ibase = FIELD_GET(PORT_ERROR_CAP_INT_VECT, v);
> inr = FIELD_GET(PORT_ERROR_CAP_SUPP_INT, v);
> break;
> case FME_FEATURE_ID_GLOBAL_ERR:
> + if (type != FME_ID)
> + break;
> v = readq(base + FME_ERROR_CAP);
> ibase = FIELD_GET(FME_ERROR_CAP_INT_VECT, v);
> inr = FIELD_GET(FME_ERROR_CAP_SUPP_INT, v);