| Message ID | 1448066790-19591-2-git-send-email-rodrigo.vivi@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, 21 Nov 2015, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote: > 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; How about the ->transfer call in drm_dp_i2c_do_msg? If we leave that for the i2c layer (which does do retries on -EAGAIN, but also handles timeouts for repeated -EAGAINs) it deserves a comment in in drm_dp_i2c_do_msg. BR, Jani. > + > + /* FIXME: On BUSY we could wait before retrying */ > if (err == -EBUSY) > continue;
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;
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(+)