Message ID | 20210320083739.724246-1-quanyang.wang@windriver.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | drm: xlnx: zynqmp: release reset to DP controller before accessing DP registers | expand |
Hi Quanyang, Thank you for the patch. On Sat, Mar 20, 2021 at 04:37:39PM +0800, quanyang.wang@windriver.com wrote: > From: Quanyang Wang <quanyang.wang@windriver.com> > > 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@windriver.com> > --- > 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() ?
Hi Laurent, On 3/21/21 4:08 AM, Laurent Pinchart wrote: > Hi Quanyang, > > Thank you for the patch. > > On Sat, Mar 20, 2021 at 04:37:39PM +0800, quanyang.wang@windriver.com wrote: >> From: Quanyang Wang <quanyang.wang@windriver.com> >> >> 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@windriver.com> >> --- >> 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. Thank you for the suggestions. zynqmp_dp_reset(dp, true) should be added in the error path, I will add this in the V2 patch. > > For symmetry, should we also move the zynqmp_dp_reset() call from > zynqmp_dp_phy_exit() to zynqmp_dp_remove() ? Yes, I will move it out of zynqmp_dp_phy_exit and to zynqmp_dp_remove() in the V2 patch. Thanks, Quanyang
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; + ret = zynqmp_dp_phy_probe(dp); if (ret) return ret;