[PATCH RFC 21/46] drm: provide a helper for the encoder possible_crtcs mask

[David Herrmann]

Hi

On Fri, Jan 3, 2014 at 5:13 PM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Fri, Jan 03, 2014 at 05:05:46PM +0100, David Herrmann wrote:
>> Hi
>>
>> On Thu, Jan 2, 2014 at 10:27 PM, Russell King
>> <rmk+kernel at arm.linux.org.uk> wrote:
>> > The encoder possible_crtcs mask identifies which CRTCs can be bound to
>> > a particular encoder.  Each bit from bit 0 defines an index in the list
>> > of CRTCs held in the DRM mode_config crtc_list.  Rather than having
>> > drivers trying to track the position of their CRTCs in the list, expose
>> > the code which already exists for calculating the appropriate mask bit
>> > for a CRTC.
>> >
>> > Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
>> > ---
>> >  drivers/gpu/drm/drm_crtc_helper.c |   39 ++++++++++++++++++++++++------------
>> >  include/drm/drm_crtc_helper.h     |    1 +
>> >  2 files changed, 27 insertions(+), 13 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
>> > index 01361aba033b..10708c248196 100644
>> > --- a/drivers/gpu/drm/drm_crtc_helper.c
>> > +++ b/drivers/gpu/drm/drm_crtc_helper.c
>> > @@ -325,6 +325,29 @@ void drm_helper_disable_unused_functions(struct drm_device *dev)
>> >  EXPORT_SYMBOL(drm_helper_disable_unused_functions);
>> >
>> >  /**
>> > + * drm_helper_crtc_possible_mask - find the mask of a registered CRTC
>> > + * @crtc: crtc to find mask for
>> > + *
>> > + * Given a registered CRTC, return the mask bit of that CRTC for an
>> > + * encoder's possible_crtcs field.
>>
>> I think this is a nice cleanup which we could pick up right away. Most
>> drivers can be simplified by using this. Only the name is misleading,
>> imo, I'd use something like drm_helper_crtc_to_mask().
>
> I'm not so sure - since the only place this mask gets used is with
> the "possible_crtcs" field.  It's got nothing to do with the
> "possible_clones" field as that isn't a mask of CRTCs.

At least intel's copy of intel_crtc_encoder_ok() can be updated, too.
But they don't depend on the crtc_helpers so we'd have to move your
small helper into drm_crtc.c (which is fine to me as it is not limited
to the DRM-crtc-helpers).

possible_clones is about encoders, you're right, I missed that. So you
can carry it in your series just fine.

Thanks
David