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SubjectRe: [PATCH v2 4/6] fpga: dfl: add generic support for MSIX interrupts


On Fri, 23 Sep 2022, Ilpo Järvinen wrote:

> On Fri, 23 Sep 2022, matthew.gerlach@linux.intel.com wrote:
>
>> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>
>> Define and use a DFHv1 parameter to add generic support for MSIX
>> interrupts for DFL devices.
>>
>> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>> ---
>> v2: fix kernel doc
>> clarify use of DFH_VERSION field
>> ---
>> drivers/fpga/dfl.c | 60 +++++++++++++++++++++++++++++++++++++++++----
>> include/linux/dfl.h | 14 +++++++++++
>> 2 files changed, 69 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
>> index 1132f3c10440..dfd3f563c92d 100644
>> --- a/drivers/fpga/dfl.c
>> +++ b/drivers/fpga/dfl.c
>> @@ -941,23 +941,22 @@ 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;
>> + int virq, off;
>> u64 v;
>>
>> type = feature_dev_id_type(binfo->feature_dev);
>>
>> /*
>> * Ideally DFL framework should only read info from DFL header, but
>> - * current version DFL only provides mmio resources information for
>> + * current version, DFHv0, only provides mmio resources information for
>> * each feature in DFL Header, no field for interrupt resources.
>> * Interrupt resource information is provided by specific mmio
>> * registers of each private feature which supports interrupt. So in
>> * order to parse and assign irq resources, DFL framework has to look
>> * into specific capability registers of these private features.
>> *
>> - * Once future DFL version supports generic interrupt resource
>> - * information in common DFL headers, the generic interrupt parsing
>> - * code will be added. But in order to be compatible to old version
>> + * DFHv1 supports generic interrupt resource information in DFHv1
>> + * parameter blocks. But in order to be compatible to old version
>> * DFL, the driver may still fall back to these quirks.
>> */
>> if (type == PORT_ID) {
>> @@ -981,6 +980,36 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
>> }
>> }
>>
>> + if (fid != FEATURE_ID_AFU && fid != PORT_FEATURE_ID_ERROR &&
>> + fid != PORT_FEATURE_ID_UINT && fid != FME_FEATURE_ID_GLOBAL_ERR) {
>> +
>> + v = FIELD_GET(DFH_VERSION, readq(base));
>
> I'd call this variable version (or ver) if you want to store it but it
> would also fit to switch () line so that no extra variable is needed.

I will change the v to dfh_ver to be clearer. I want to store the
value because it is used in the default case in the error message. The
error message helps to debug broken FPGA images.

>
>> + switch (v) {
>> + case 0:
>> + break;
>> +
>> + case 1:
>> + v = readq(base + DFHv1_CSR_SIZE_GRP);
>
> Extra space.

I will remove extra space.

>
>> + if (FIELD_GET(DFHv1_CSR_SIZE_GRP_HAS_PARAMS, v)) {
>> + off = dfl_find_param(base + DFHv1_PARAM_HDR, ofst,
>> + DFHv1_PARAM_ID_MSIX);
>> + if (off >= 0) {
>
> I'd reverse these 2 conditions and break when there's nothing to do.

I'm not sure what you mean by reversing these conditions because a DFHv1
may or may not have parameters (the first condition), and a DFHv1 may have
parameters but may not have a MSI-X parameter (the second condition).

>
>> + ibase = readl(base + DFHv1_PARAM_HDR +
>> + off + DFHv1_PARAM_MSIX_STARTV);
>> + inr = readl(base + DFHv1_PARAM_HDR +
>> + off + DFHv1_PARAM_MSIX_NUMV);
>> + dev_dbg(binfo->dev, "start %d num %d fid 0x%x\n",
>> + ibase, inr, fid);
>> + }
>> + }
>> + break;
>> +
>> + default:
>> + dev_warn(binfo->dev, "unexpected DFH version %lld\n", v);
>> + break;
>> + }
>> + }
>> +
>> if (!inr) {
>> *irq_base = 0;
>> *nr_irqs = 0;
>
> --
> i.
>
>
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