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

["Zhang, Tianfei" <tianfei.zhang@intel.com>]

> -----Original Message-----
> From: Tom Rix <trix@redhat.com>
> Sent: Friday, February 18, 2022 10:30 PM
> To: Zhang, Tianfei <tianfei.zhang@intel.com>; Wu, Hao <hao.wu@intel.com>;
> mdf@kernel.org; Xu, Yilun <yilun.xu@intel.com>; linux-fpga@vger.kernel.org;
> linux-doc@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: corbet@lwn.net
> Subject: Re: [PATCH v1 2/7] fpga: dfl: check feature type before parse irq info
> 
> 
> On 2/17/22 10:53 PM, Zhang, Tianfei wrote:
> >
> >> -----Original Message-----
> >> From: Tom Rix <trix@redhat.com>
> >> Sent: Tuesday, February 15, 2022 10:49 PM
> >> To: Zhang, Tianfei <tianfei.zhang@intel.com>; Wu, Hao
> >> <hao.wu@intel.com>; mdf@kernel.org; Xu, Yilun <yilun.xu@intel.com>;
> >> linux-fpga@vger.kernel.org; linux-doc@vger.kernel.org;
> >> linux-kernel@vger.kernel.org
> >> Cc: corbet@lwn.net
> >> Subject: Re: [PATCH v1 2/7] fpga: dfl: check feature type before
> >> parse irq info
> >>
> >>
> >> 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.
> 
> ?

I agree, I will send this patch as a bug fix.

> 
> >>
> >> 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 ?
> > This patch is not workaround, this is a bug fix for DFL driver.
> > The root cause is that DLF driver miss check the feature type while
> > parsing the interrupt information, because some Feature IDs are identical
> between FME and Port, like PMCI in FME and "Port User Interrupt"
> > in Port.
> > The definition of Feature ID is here:
> > https://github.com/OPAE/linux-dfl-feature-id/blob/master/dfl-feature-i
> > ds.rst
> Helpful but hidden.  At least a link to this should be added to
> Documentation/fpga/dfl.rst.
> >>> 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
> > Your suggestion is looks good  for me, I will change on next version.
> >
> >> 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);