On Tue, Aug 28, 2018 at 09:06:15PM +0300, Ville Syrjälä wrote:
> On Tue, Aug 28, 2018 at 10:41:46AM -0700, Lucas De Marchi wrote:
> > Document it like a real struct for ease of copy and paste, remove
> > comment of C99 compatibility and document that in some cases the first 2
> > fields can be u16.
> >
> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> > ---
> > include/drm/i915_pciids.h | 16 +++++++++-------
> > 1 file changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/include/drm/i915_pciids.h b/include/drm/i915_pciids.h
> > index 754ce4b10129..0c2cc43f916c 100644
> > --- a/include/drm/i915_pciids.h
> > +++ b/include/drm/i915_pciids.h
> > @@ -26,14 +26,16 @@
> > #define _I915_PCIIDS_H
> >
> > /*
> > - * A pci_device_id struct {
> > - * __u32 vendor, device;
> > - * __u32 subvendor, subdevice;
> > - * __u32 class, class_mask;
> > - * kernel_ulong_t driver_data;
> > + * These macros can be used with a struct declared like this:
> > + *
> > + * struct pci_device_id {
> > + * __u32 vendor, device;
> > + * __u32 subvendor, subdevice;
> > + * __u32 class, class_mask;
> > + * kernel_ulong_t driver_data;
> > * };
> > - * Don't use C99 here because "class" is reserved and we want to
> > - * give userspace flexibility.
> > + *
> > + * First two fields may be __u16 if PCI_DEVICE_ANY is not used
>
> PCI_DEVICE_ANY undefined?
this should be PCI_ANY_ID, but now I'm not sure if I should even mention
it since it's defined somewhere that's private to kernel.
>
> Also you can surely use u16 just fine as long as you're careful when
> comparing with ~0?
nops, since ~0u is unsigned int (~0 being int before patch 1), it will
overflow and cause a warning due to -Woverflow. This is what happens in
igt if I do what you said:
../intel/i915_pciids.h:40:2: warning: conversion from ‘unsigned int’ to ‘short unsigned int’ changes value from ‘4294967295’ to ‘65535’ [-Woverflow]
~0u, ~0u, \
^
Lucas De Marchi
>
> > */
> > #define INTEL_VGA_DEVICE(id, info) { \
> > 0x8086, id, \
> > --
> > 2.17.1
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Ville Syrjälä
> Intel
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