[PATCH] drm: Use EOPNOTSUPP, not ENOTSUPP

[Daniel Vetter]

On Wed, Sep 4, 2019 at 9:58 PM Souza, Jose <jose.souza at intel.com> wrote:
>
> On Wed, 2019-09-04 at 16:39 +0200, Daniel Vetter wrote:
> > - it's what we recommend in our docs:
> >
> > https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#recommended-ioctl-return-values
> >
> > - it's the overwhelmingly used error code for "operation not
> >   supported", at least in drm core (slightly less so in drivers):
> >
> > $ git grep EOPNOTSUP -- drivers/gpu/drm/*c | wc -l
> > 83
> > $ git grep ENOTSUP -- drivers/gpu/drm/*c | wc -l
> > 5
> >
> > - include/linux/errno.h makes it fairly clear that these are for
> > nfsv3
> >   (plus they also have error codes above 512, which is the block with
> >   some special behaviour ...)
> >
> > /* Defined for the NFSv3 protocol */
> >
> > If the above isn't reflecting current practice, then I guess we
> > should
> > at least update the docs.
>
> Hopefully this will not break any userspace

None of the functions in drm_edid.c affected by this reach userspace,
it's all driver internal.

Same for the mipi function, that error code should be handled by
drivers. Drivers are supposed to remap "the hw is on fire" to EIO when
reporting up to userspace, but I think if a driver sees this it would
be a driver bug.

So no way this goes out to userspace, I really only did this to have
the drm core/helpers be 100% consistent with our documented
recommendations here.

I'll summarize the above in the commit message when I merge the patch.

> Reviewed-by: José Roberto de Souza <jose.souza at intel.com>

Thanks, Daniel

>
> >
> > Cc: José Roberto de Souza <jose.souza at intel.com>
> > Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > Cc: Maxime Ripard <mripard at kernel.org>
> > Cc: Sean Paul <sean at poorly.run>
> > Cc: Alex Deucher <alexander.deucher at amd.com>
> > Cc: Andres Rodriguez <andresx7 at gmail.com>
> > Cc: Noralf Trønnes <noralf at tronnes.org>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >  drivers/gpu/drm/drm_edid.c     | 6 +++---
> >  drivers/gpu/drm/drm_mipi_dbi.c | 2 +-
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index 82a4ceed3fcf..12c783f4d956 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -3719,7 +3719,7 @@ cea_db_offsets(const u8 *cea, int *start, int
> > *end)
> >               if (*end < 4 || *end > 127)
> >                       return -ERANGE;
> >       } else {
> > -             return -ENOTSUPP;
> > +             return -EOPNOTSUPP;
> >       }
> >
> >       return 0;
> > @@ -4188,7 +4188,7 @@ int drm_edid_to_sad(struct edid *edid, struct
> > cea_sad **sads)
> >
> >       if (cea_revision(cea) < 3) {
> >               DRM_DEBUG_KMS("SAD: wrong CEA revision\n");
> > -             return -ENOTSUPP;
> > +             return -EOPNOTSUPP;
> >       }
> >
> >       if (cea_db_offsets(cea, &start, &end)) {
> > @@ -4249,7 +4249,7 @@ int drm_edid_to_speaker_allocation(struct edid
> > *edid, u8 **sadb)
> >
> >       if (cea_revision(cea) < 3) {
> >               DRM_DEBUG_KMS("SAD: wrong CEA revision\n");
> > -             return -ENOTSUPP;
> > +             return -EOPNOTSUPP;
> >       }
> >
> >       if (cea_db_offsets(cea, &start, &end)) {
> > diff --git a/drivers/gpu/drm/drm_mipi_dbi.c
> > b/drivers/gpu/drm/drm_mipi_dbi.c
> > index c4ee2709a6f3..f8154316a3b0 100644
> > --- a/drivers/gpu/drm/drm_mipi_dbi.c
> > +++ b/drivers/gpu/drm/drm_mipi_dbi.c
> > @@ -955,7 +955,7 @@ static int mipi_dbi_typec1_command(struct
> > mipi_dbi *dbi, u8 *cmd,
> >       int ret;
> >
> >       if (mipi_dbi_command_is_read(dbi, *cmd))
> > -             return -ENOTSUPP;
> > +             return -EOPNOTSUPP;
> >
> >       MIPI_DBI_DEBUG_COMMAND(*cmd, parameters, num);
> >



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch