[PATCH] drm/rockchip: vop2: Fix Null Pointer Dereference on Multiple VPs
Sascha Hauer
sha at pengutronix.de
Mon Sep 26 01:17:40 PDT 2022
On Thu, Sep 15, 2022 at 10:13:44AM -0500, Chris Morgan wrote:
> On Wed, Sep 14, 2022 at 03:35:30PM +0200, Sascha Hauer wrote:
> > On Wed, Sep 14, 2022 at 08:04:18AM -0500, Chris Morgan wrote:
> > > On Wed, Sep 14, 2022 at 08:49:27AM +0200, Sascha Hauer wrote:
> > > > On Tue, Sep 13, 2022 at 08:55:22AM +0200, Michael Riesch wrote:
> > > > > Hi,
> > > > >
> > > > > On 9/12/22 20:02, Chris Morgan wrote:
> > > > > > From: Chris Morgan <macromorgan at hotmail.com>
> > > > >
> > > > > Cc: Sascha -> any thoughts on this one?
> > > > >
> > > > > Best regards,
> > > > > Michael
> > > > >
> > > > > > If I use more than one VP to output on an RK3566 based device I
> > > > > > receive the following error (and then everything freezes):
> > > > > >
> > > > > > [ 0.838375] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000250
> > > > > > [ 0.839191] Mem abort info:
> > > > > > [ 0.839442] ESR = 0x0000000096000005
> > > > > > [ 0.839785] EC = 0x25: DABT (current EL), IL = 32 bits
> > > > > > [ 0.840256] SET = 0, FnV = 0
> > > > > > [ 0.840530] EA = 0, S1PTW = 0
> > > > > > [ 0.840821] FSC = 0x05: level 1 translation fault
> > > > > > [ 0.841254] Data abort info:
> > > > > > [ 0.841512] ISV = 0, ISS = 0x00000005
> > > > > > [ 0.841864] CM = 0, WnR = 0
> > > > > > [ 0.842130] [0000000000000250] user address but active_mm is swapper
> > > > > > [ 0.842704] Internal error: Oops: 96000005 [#1] SMP
> > > > > > [ 0.843139] Modules linked in:
> > > > > > [ 0.843420] CPU: 0 PID: 37 Comm: kworker/u8:1 Not tainted 6.0.0-rc5+ #40
> > > > > > [ 0.844013] Hardware name: RG503 (DT)
> > > > > > [ 0.844343] Workqueue: events_unbound deferred_probe_work_func
> > > > > > [ 0.844871] pstate: 80000009 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > > > > > [ 0.845487] pc : __drm_crtc_init_with_planes+0x48/0x2e4
> > > > > > [ 0.845956] lr : drm_crtc_init_with_planes+0x68/0x94
> > > > > > [ 0.846399] sp : ffffffc00a7a3710
> > > > > > [ 0.846695] x29: ffffffc00a7a3710 x28: ffffff8000fb4080 x27: ffffffc00a7a37a0
> > > > > > [ 0.847332] x26: ffffffc0097d01c7 x25: ffffff8000fb44d8 x24: ffffffc0097d01c7
> > > > > > [ 0.847967] x23: ffffffc009311870 x22: 0000000000000000 x21: 0000000000000008
> > > > > > [ 0.848603] x20: ffffff80010d0800 x19: ffffff8000fb44e8 x18: 0000000000000000
> > > > > > [ 0.849237] x17: 08000000000000d1 x16: 0800000000000091 x15: 08000000000000c1
> > > > > > [ 0.849874] x14: 0000000000000000 x13: 3432564e3631564e x12: 3231564e36314742
> > > > > > [ 0.850509] x11: 3631475234324742 x10: 000000000000002d x9 : ffffffc008682004
> > > > > > [ 0.851144] x8 : 00000000006f7475 x7 : 00000000fffffff0 x6 : ffffffc00a7a37a0
> > > > > > [ 0.851778] x5 : ffffffc0097d01c7 x4 : ffffffc009311870 x3 : 0000000000000000
> > > > > > [ 0.852412] x2 : 0000000000000008 x1 : ffffff8000fb44e8 x0 : ffffff80010d0800
> > > > > > [ 0.853048] Call trace:
> > > > > > [ 0.853270] __drm_crtc_init_with_planes+0x48/0x2e4
> > > > > > [ 0.853706] drm_crtc_init_with_planes+0x68/0x94
> > > > > > [ 0.854118] vop2_bind+0x89c/0x920
> > > > > > [ 0.854429] component_bind_all+0x18c/0x290
> > > > > > [ 0.854805] rockchip_drm_bind+0xe4/0x1f0
> > > > > > [ 0.855166] try_to_bring_up_aggregate_device+0x9c/0x290
> > > > > > [ 0.855639] __component_add+0x110/0x168
> > > > > > [ 0.855991] component_add+0x1c/0x28
> > > > > > [ 0.856312] dw_mipi_dsi_rockchip_host_attach+0x98/0x10c
> > > > > > [ 0.856785] dw_mipi_dsi_host_attach+0xbc/0xd0
> > > > > > [ 0.857184] mipi_dsi_attach+0x30/0x44
> > > > > > [ 0.857521] devm_mipi_dsi_attach+0x2c/0x70
> > > > > > [ 0.857896] ams495qa01_probe+0x2d4/0x33c
> > > > > > [ 0.858257] spi_probe+0x8c/0xb8
> > > > > > [ 0.858550] really_probe+0x1e0/0x3b8
> > > > > > [ 0.858881] __driver_probe_device+0x16c/0x184
> > > > > > [ 0.859278] driver_probe_device+0x4c/0xfc
> > > > > > [ 0.859646] __device_attach_driver+0xf0/0x170
> > > > > > [ 0.860043] bus_for_each_drv+0xa4/0xcc
> > > > > > [ 0.860389] __device_attach+0xfc/0x1a8
> > > > > > [ 0.860733] device_initial_probe+0x1c/0x28
> > > > > > [ 0.861108] bus_probe_device+0x38/0x9c
> > > > > > [ 0.861452] deferred_probe_work_func+0xdc/0xf0
> > > > > > [ 0.861855] process_one_work+0x1b0/0x260
> > > > > > [ 0.862217] process_scheduled_works+0x4c/0x50
> > > > > > [ 0.862614] worker_thread+0x1f0/0x26c
> > > > > > [ 0.862949] kthread+0xc4/0xd4
> > > > > > [ 0.863227] ret_from_fork+0x10/0x20
> > > > > > [ 0.863553] Code: aa0503fa f9002bfb aa0603fb b40000a2 (b9424840)
> > > > > > [ 0.864095] ---[ end trace 0000000000000000 ]---
> > > > > >
> > > > > > A cursory reading of the datasheet suggests it's possible to have
> > > > > > simultaneous output to 2 distinct outputs. On page 13 it states:
> > > > > >
> > > > > > Support two simultaneous displays(same source) in the following interfaces:
> > > > > > - MIPI_DSI_TX
> > > > > > - LVDS
> > > > > > - HDMI
> > > > > > - eDP
> > > > > >
> > > > > > In order to achieve this though, I need to output to VP0 and VP1 (or
> > > > > > any 2 distinct VPs really). This is so I can have the ref clock set
> > > > > > to 24MHz for the HDMI and the pixel clock of the DSI panel (for the
> > > > > > example above it's 33.5MHz). Currently, only by removing this code
> > > > > > block is such a thing possible, though I'm not sure if long-term
> > > > > > there should only be 1 CRTC for the rk3566 (and 2 CRTCs for 3568)
> > > > > > along with a max of 2 encoders for rk3566 (and 3 encoders for 3568).
> > > > > >
> > > > > > Fixes: 604be85547ce ("drm/rockchip: Add VOP2 driver")
> > > > > >
> > > > > > Signed-off-by: Chris Morgan <macromorgan at hotmail.com>
> > > > > > ---
> > > > > > drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 14 --------------
> > > > > > 1 file changed, 14 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > > > > > index e4631f515ba4..f18d7f6f9f86 100644
> > > > > > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > > > > > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > > > > > @@ -2289,20 +2289,6 @@ static int vop2_create_crtc(struct vop2 *vop2)
> > > > > > struct vop2_win *win = &vop2->win[i];
> > > > > > u32 possible_crtcs;
> > > > > >
> > > > > > - if (vop2->data->soc_id == 3566) {
> > > > > > - /*
> > > > > > - * On RK3566 these windows don't have an independent
> > > > > > - * framebuffer. They share the framebuffer with smart0,
> > > > > > - * esmart0 and cluster0 respectively.
> > > > > > - */
> > > > > > - switch (win->data->phys_id) {
> > > > > > - case ROCKCHIP_VOP2_SMART1:
> > > > > > - case ROCKCHIP_VOP2_ESMART1:
> > > > > > - case ROCKCHIP_VOP2_CLUSTER1:
> > > > > > - continue;
> > > > > > - }
> > > > > > - }
> > > >
> > > > Let me say that a "window" in the Rockchip terminology is what a plane
> > > > is in the DRM terminology, and a video port (vp) corresponds to a crtc.
> > > >
> > > > On the RK3566 some windows do not have their own framebuffer, for
> > > > example the smart1 window always shows what the smart0 window shows.
> > > > This "feature" makes these windows unusable as planes, so the idea is to
> > > > simply not use them.
> > > >
> > > > If skipping these windows from initialization results in a NULL pointer
> > > > deref then there's something wrong in the driver logic, but it's not the
> > > > lines you are removing here that are wrong. Nothing should prevent you
> > > > from using multiple VPs when the unusable windows on RK3566 are not
> > > > registered.
> > >
> > > I'll tell you what I "think" is causing the null pointer deref, but like
> > > always I reserve the right to be wrong.
> > >
> > > The driver checks for the primary planes and assigns them to active
> > > video ports. For the rk3566 it's skipping the 3 planes mentioned
> > > above for the RK3566. As a result if there is more than 1 active video
> > > port for the rk3566 (or more than 2 for the rk3568 I'm assuming) it
> > > doesn't set vp->primary_plane = win for that port. Slightly below that
> > > it iterates through the active video ports again and runs
> > > drm_crtc_init_with_planes on them. Only in this case one of the ports
> > > doesn't have a plane, which is where it does the null pointer deref,
> > > because the plane is null.
> >
> > Yes, you're right, that is likely the problem.
> >
> > On RK3568 we have four windows that could serve as primary plane, so
> > there's enough for each of the three VPs. On RK3566 we only have two
> > windows, so once we use more than two active VPs we are running out of
> > primary planes.
>
> The datasheet states that it supports up to 2 simultaneous displays, so
> I think a hard limit of 2 VPs is fine for the rk3566.
>
> >
> > I am writing these numbers because I think Esmart0-win0 could be used as
> > primary plane, but is marked as DRM_PLANE_TYPE_OVERLAY in
> > rk3568_vop_win_data[]. See the attached patch, if that's the problem it
> > should resolve your issue.
>
> This patch did indeed resolve my issue, and also allowed me to get both
> HDMI and DSI working simultaneously. It's not perfect (right now I'm
> displaying a 640x480 image on a 1080p display since my DSI panel runs
> at 640x480), but it works and that's great.
I just sent this patch for inclusion. Could you provide your formal
tested-by: tag?
Sascha
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