Re: [PATCH 03/14] cxl/mem: Find device capabilities

Ben Widawsky
2021-02-01T17:52:22Z

On 21-02-01 12:41:36, Konrad Rzeszutek Wilk wrote:
> > +static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
> > +{
> > + struct device *dev = &cxlm->pdev->dev;
> > + int cap, cap_count;
> > + u64 cap_array;
> > +
> > + cap_array = readq(cxlm->regs + CXLDEV_CAP_ARRAY_OFFSET);
> > + if (CXL_GET_FIELD(cap_array, CXLDEV_CAP_ARRAY_ID) != CXLDEV_CAP_ARRAY_CAP_ID)
> > + return -ENODEV;
> > +
> > + cap_count = CXL_GET_FIELD(cap_array, CXLDEV_CAP_ARRAY_COUNT);
> > +
> > + for (cap = 1; cap <= cap_count; cap++) {
> > + void __iomem *register_block;
> > + u32 offset;
> > + u16 cap_id;
> > +
> > + cap_id = readl(cxlm->regs + cap * 0x10) & 0xffff;
> > + offset = readl(cxlm->regs + cap * 0x10 + 0x4);
> > + register_block = cxlm->regs + offset;
> > +
> > + switch (cap_id) {
> > + case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
> > + dev_dbg(dev, "found Status capability (0x%x)\n",
> > + offset);
>
> That 80 character limit is no longer a requirement. Can you just make
> this one line? And perhaps change 'found' to 'Found' ?
>

Funny that.
https://lore.kernel.org/linux-cxl/20201111073449.GA16235@infradead.org/

> > + cxlm->status.regs = register_block;
> > + break;
> > + case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
> > + dev_dbg(dev, "found Mailbox capability (0x%x)\n",
> > + offset);
> > + cxlm->mbox.regs = register_block;
> > + break;
> > + case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
> > + dev_dbg(dev,
> > + "found Secondary Mailbox capability (0x%x)\n",
> > + offset);
> > + break;
> > + case CXLDEV_CAP_CAP_ID_MEMDEV:
> > + dev_dbg(dev, "found Memory Device capability (0x%x)\n",
> > + offset);
> > + cxlm->mem.regs = register_block;
> > + break;
> > + default:
> > + dev_warn(dev, "Unknown cap ID: %d (0x%x)\n", cap_id,
> > + offset);
> > + break;
> > + }
> > + }
> > +
> > + if (!cxlm->status.regs || !cxlm->mbox.regs || !cxlm->mem.regs) {
> > + dev_err(dev, "registers not found: %s%s%s\n",
> > + !cxlm->status.regs ? "status " : "",
> > + !cxlm->mbox.regs ? "mbox " : "",
> > + !cxlm->mem.regs ? "mem" : "");
> > + return -ENXIO;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int cxl_mem_setup_mailbox(struct cxl_mem *cxlm)
> > +{
> > + const int cap = cxl_read_mbox_reg32(cxlm, CXLDEV_MB_CAPS_OFFSET);
> > +
> > + cxlm->mbox.payload_size =
> > + 1 << CXL_GET_FIELD(cap, CXLDEV_MB_CAP_PAYLOAD_SIZE);
> > +
>
> I think the static analyzers are not going to be happy that you are not
> checking the value of `cap` before using it.
>
> Perhaps you should check that first before doing the manipulations?
>

I'm not following the request. CXL_GET_FIELD is just doing the shift and mask on
cap.

Can you explain what you're hoping to see?

> > + /* 8.2.8.4.3 */
> > + if (cxlm->mbox.payload_size < 256) {
>
> #define for 256?