Re: [Intel-gfx] [PATCH v4 1/4] drm/i915/fbc: Clear frontbuffer busy bits on flip

["Coelho, Luciano" <luciano.coelho@intel.com>]

Hi Jouni,

On Fri, 2023-09-01 at 12:34 +0300, Jouni Högander wrote:
> We are planning to move flush performed from work queue. This
> means it is possible to have invalidate -> flip -> flush sequence.
> Handle this by clearing possible busy bits on flip.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_fbc.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> index 1c6d467cec26..817e5784660b 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -1307,11 +1307,9 @@ static void __intel_fbc_post_update(struct intel_fbc *fbc)
>  	lockdep_assert_held(&fbc->lock);
>  
>  	fbc->flip_pending = false;
> +	fbc->busy_bits = 0;
>  
> -	if (!fbc->busy_bits)
> -		intel_fbc_activate(fbc);
> -	else
> -		intel_fbc_deactivate(fbc, "frontbuffer write");
> +	intel_fbc_activate(fbc);

Can you explain why the call to intel_fbc_deactivate() is not needed
here anymore? I think it would be a good idea to explain that in the
commit message.  Or, at least, an explanation about it here, so it's
documented. ;)

--
Cheers,
Luca.