Hi Quanyang, Thank you for the patch. On Sat, Mar 20, 2021 at 04:37:39PM +0800, quanyang.wang@xxxxxxxxxxxxx wrote: > From: Quanyang Wang <quanyang.wang@xxxxxxxxxxxxx> > > When insmod zynqmp-dpsub.ko after rmmod it, system will hang with the > error log as below: > > root@xilinx-zynqmp:~# insmod zynqmp-dpsub.ko > [ 88.391289] [drm] Initialized zynqmp-dpsub 1.0.0 20130509 for fd4a0000.display on minor 0 > [ 88.529906] Console: switching to colour frame buffer device 128x48 > [ 88.549402] zynqmp-dpsub fd4a0000.display: [drm] fb0: zynqmp-dpsubdrm frame buffer device > [ 88.571624] zynqmp-dpsub fd4a0000.display: ZynqMP DisplayPort Subsystem driver probed > root@xilinx-zynqmp:~# rmmod zynqmp_dpsub > [ 94.023404] Console: switching to colour dummy device 80x25 > root@xilinx-zynqmp:~# insmod zynqmp-dpsub.ko > <hang here> > > This is because that in zynqmp_dp_probe it tries to access some DP > registers while the DP controller is still in the reset state. When > running "rmmod zynqmp_dpsub", zynqmp_dp_reset(dp, true) in > zynqmp_dp_phy_exit is called to force the DP controller into the reset > state. Then insmod will call zynqmp_dp_probe to write to the DP registers, > but at this moment the DP controller isn't brought out of the reset state > since the function zynqmp_dp_reset(dp, false) is called later and this > will result the system hang. > > Releasing the reset to DP controller before any read/write operation to it > will fix this issue. > > Signed-off-by: Quanyang Wang <quanyang.wang@xxxxxxxxxxxxx> > --- > drivers/gpu/drm/xlnx/zynqmp_dp.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c > index 99158ee67d02..bb45b3663d6b 100644 > --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c > +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c > @@ -402,10 +402,6 @@ static int zynqmp_dp_phy_init(struct zynqmp_dp *dp) > } > } > > - ret = zynqmp_dp_reset(dp, false); > - if (ret < 0) > - return ret; > - > zynqmp_dp_clr(dp, ZYNQMP_DP_PHY_RESET, ZYNQMP_DP_PHY_RESET_ALL_RESET); > > /* > @@ -1682,6 +1678,10 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub, struct drm_device *drm) > return PTR_ERR(dp->reset); > } > > + ret = zynqmp_dp_reset(dp, false); > + if (ret < 0) > + return ret; > + This change looks good to me. > ret = zynqmp_dp_phy_probe(dp); > if (ret) > return ret; But shouldn't we call zynqmp_dp_reset(dp, true) here ? Or rather, call it in the error path at the end of the function, with a goto label. For symmetry, should we also move the zynqmp_dp_reset() call from zynqmp_dp_phy_exit() to zynqmp_dp_remove() ? -- Regards, Laurent Pinchart _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
