From: Quanyang Wang quanyang.wang@windriver.com
[ Upstream commit a338619bd76011035d462f0f9e8b2f24d7fe5a1e ]
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 program the DP registers, but at this moment the DP controller hasn't been brought out of the reset state yet 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. And for symmetry, move zynqmp_dp_reset() call from zynqmp_dp_phy_exit() to zynqmp_dp_remove().
Signed-off-by: Quanyang Wang quanyang.wang@windriver.com Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/xlnx/zynqmp_dp.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c index 82430ca9b913..6f588dc09ba6 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);
/* @@ -441,8 +437,6 @@ static void zynqmp_dp_phy_exit(struct zynqmp_dp *dp) ret); }
- zynqmp_dp_reset(dp, true); - for (i = 0; i < dp->num_lanes; i++) { ret = phy_exit(dp->phy[i]); if (ret) @@ -1683,9 +1677,13 @@ 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; + ret = zynqmp_dp_phy_probe(dp); if (ret) - return ret; + goto err_reset;
/* Initialize the hardware. */ zynqmp_dp_write(dp, ZYNQMP_DP_TX_PHY_POWER_DOWN, @@ -1697,7 +1695,7 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub, struct drm_device *drm)
ret = zynqmp_dp_phy_init(dp); if (ret) - return ret; + goto err_reset;
zynqmp_dp_write(dp, ZYNQMP_DP_TRANSMITTER_ENABLE, 1);
@@ -1709,15 +1707,18 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub, struct drm_device *drm) zynqmp_dp_irq_handler, IRQF_ONESHOT, dev_name(dp->dev), dp); if (ret < 0) - goto error; + goto err_phy_exit;
dev_dbg(dp->dev, "ZynqMP DisplayPort Tx probed with %u lanes\n", dp->num_lanes);
return 0;
-error: +err_phy_exit: zynqmp_dp_phy_exit(dp); +err_reset: + zynqmp_dp_reset(dp, true); + return ret; }
@@ -1735,4 +1736,5 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub) zynqmp_dp_write(dp, ZYNQMP_DP_INT_DS, 0xffffffff);
zynqmp_dp_phy_exit(dp); + zynqmp_dp_reset(dp, true); }