Commit a338619b authored by Quanyang Wang's avatar Quanyang Wang Committed by Laurent Pinchart
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drm: xlnx: zynqmp: release reset to DP controller before accessing DP registers 



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: default avatarQuanyang Wang <quanyang.wang@windriver.com>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
parent 97271c7e

drivers/gpu/drm/xlnx/zynqmp_dp.c

+12 −10
Original line number Diff line number Diff line
@@ -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);

}