The goal here is to offload aux retries handling from the drivers to drm.
However there are 2 differents cases for retry: 1. Immediately retry - Hardware already took care of needed timeouts before answering that a retry is possible. 2. Busy - Wait some time and retry.
This driver introduce the support for EAGAIN that can handle the first case and a following patch will introduce EBUSY waits, after all drivers counting on immediately retries are changed.
Cc: Dave Airlie airlied@redhat.com Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com --- drivers/gpu/drm/drm_dp_helper.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 9535c5b..ee7c955 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -198,6 +198,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, err = aux->transfer(aux, &msg); mutex_unlock(&aux->hw_mutex); if (err < 0) { + /* Immediately retry */ + if (err == -EAGAIN) + continue; + + /* FIXME: On BUSY we could wait before retrying */ if (err == -EBUSY) continue;