Hi Tomi, Thank you for the patch. On Friday 26 February 2016 11:35:50 Tomi Valkeinen wrote: > The current driver uses non-blocking DMM fill when releasing memory. > This gives us a small performance increase as we don't have to wait for > the fill operation to finish. > > However, the driver does not have any error handling for non-blocking > fill. In case of an error, the fill operation may silently fail, leading > to leaking DMM engines, which may eventually lead to deadlock if we run > out of DMM engines. > > This patch makes the DMM driver always use blocking fills, so that we > can catch the errors. A more complex option would be to allow > non-blocking fills, and implement proper error handling, but that is > left for the future. > > This patch is a HACK, as the proper fix is to either decide to always > use sync fills and remove all the async related code, or fix the async > code. > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/omapdrm/omap_dmm_tiler.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c > b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c index dfebdc4aa0f2..67edf839dce3 > 100644 > --- a/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c > +++ b/drivers/gpu/drm/omapdrm/omap_dmm_tiler.c > @@ -309,6 +309,21 @@ static int fill(struct tcm_area *area, struct page > **pages, struct tcm_area slice, area_s; > struct dmm_txn *txn; > > + /* > + * FIXME > + * > + * Asynchronous fill does not work reliably, as the driver does not > + * handle errors in the async code paths. The fill operation may > + * silently fail, leading to leaking DMM engines, which may eventually > + * lead to deadlock if we run out of DMM engines. > + * > + * For now, always set 'wait' so that we only use sync fills. Async > + * fills should be fixed, or alternatively we could decide to only > + * support sync fills and so the whole async code path could be removed. > + */ > + > + wait = true; > + > txn = dmm_txn_init(omap_dmm, area->tcm); > if (IS_ERR_OR_NULL(txn)) > return -ENOMEM; -- Regards, Laurent Pinchart _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
