fpga: of-fpga-region: accept overlays that don't program FPGA

The FPGA may already have a static image programmed when
Linux boots.  In that case a DT overlay may be used to add
the devices that already exist.  This commit allows that
by shuffling the order of some checks.

Signed-off-by: Alan Tull <atull@kernel.org>
Acked-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/fpga/of-fpga-region.c b/drivers/fpga/of-fpga-region.c
index 1533506ef0e4..c6b21194dcbc 100644
--- a/drivers/fpga/of-fpga-region.c
+++ b/drivers/fpga/of-fpga-region.c
@@ -298,18 +298,19 @@ static int of_fpga_region_notify_pre_apply(struct fpga_region *region,
         struct fpga_image_info *info;
         int ret;
 
-        if (region->info) {
-                dev_err(dev, "Region already has overlay applied.\n");
-                return -EINVAL;
-        }
-
         info = of_fpga_region_parse_ov(region, nd->overlay);
         if (IS_ERR(info))
                 return PTR_ERR(info);
 
+        /* If overlay doesn't program the FPGA, accept it anyway. */
         if (!info)
                 return 0;
 
+        if (region->info) {
+                dev_err(dev, "Region already has overlay applied.\n");
+                return -EINVAL;
+        }
+
         region->info = info;
         ret = fpga_region_program_fpga(region);
         if (ret) {