Thanks for the review Jonathan -
On Wed, Jun 16, 2021 at 05:13:40PM +0100, Jonathan Cameron wrote:
> On Tue, 15 Jun 2021 17:20:38 -0700
> Alison Schofield <alison.schofield@xxxxxxxxx> wrote:
>
> > The base address for the Host Bridge port component registers is located
> > in the CXL Host Bridge Structure (CHBS) of the ACPI CXL Early Discovery
> > Table (CEDT). Retrieve the CHBS for each Host Bridge (ACPI0016 device)
> > and include that base address in the port object.
> >
> > Co-developed-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> > Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> > Signed-off-by: Alison Schofield <alison.schofield@xxxxxxxxx>
>
> Hi Alison,
>
> A few small suggestions from me.
>
> > ---
> > drivers/cxl/acpi.c | 105 ++++++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 99 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > index be357eea552c..b6d9cd45428c 100644
> > --- a/drivers/cxl/acpi.c
> > +++ b/drivers/cxl/acpi.c
> > @@ -8,6 +8,61 @@
> > #include <linux/pci.h>
> > #include "cxl.h"
> >
> > +static struct acpi_table_header *cedt_table;
> > +
> > +static struct acpi_cedt_chbs *cxl_acpi_match_chbs(struct device *dev, u32 uid)
> > +{
> > + struct acpi_cedt_chbs *chbs, *chbs_match = NULL;
> > + acpi_size len, cur = 0;
> > + void *cedt_base;
> > + int rc = 0;
> > +
> > + len = cedt_table->length - sizeof(*cedt_table);
> > + cedt_base = cedt_table + 1;
> > +
> > + while (cur < len) {
> > + struct acpi_cedt_header *c = cedt_base + cur;
> > +
> > + if (c->type != ACPI_CEDT_TYPE_CHBS) {
> > + cur += c->length;
> > + continue;
> > + }
> > +
> > + chbs = cedt_base + cur;
> > +
> > + if (chbs->header.length < sizeof(*chbs)) {
> > + dev_err(dev, "Invalid CHBS header length: %u\n",
> > + chbs->header.length);
> > + rc = -EINVAL;
>
> As below, direct return would be more obvious to my eyes.
>
Well....I decided to warn & continue on this case. See the updated flow
in v3.
> > + break;
> > + }
> > +
> > + if (chbs->uid == uid && !chbs_match) {
> > + chbs_match = chbs;
> > + cur += c->length;
> > + continue;
> > + }
> > +
> > + if (chbs->uid == uid && chbs_match) {
> > + dev_err(dev, "Duplicate CHBS UIDs %u\n", uid);
>
> Do we actually care, or should we just drop out on first match?
> I don't think think there is any obligation to catch broken tables.
>
Agree on the obligation part, but if things go wrong, this would be
nice to know. I left it in as a dev warn once. If you think that's
too strong - let me know.
> > + rc = -EINVAL;
>
> Direct return might be easier to follow.
> return ERR_PTR(-EINVAL);
>
> > + break;
> > + }
>
> Maybe more readable as (your option is fine if you prefer it).
>
> if (chbs->uuid != uid) {
> cur += c->length;
> continue;
> }
>
> if (chbs_match) {
> dev_err(dev, "D...");
> return ERR_PTR(-EINVAL);
> }
>
> chbs_match = chbs;
>
>
Thanks, I reworked the flow along these lines.
snip
> > +
> > + port = devm_cxl_add_port(host, match, dport->component_reg_phys,
> > + root_port);
> > +
>
> Nitpick, no blank line before error handling block.
>
Got it. Thanks!
snip
