Hi Marek,
2015-12-11 20:27 GMT+09:00 Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>:
> Hi Inki,
>
>
> On 2015-12-11 10:57, Inki Dae wrote:
>>
>> Hi Marek,
>>
>> 2015년 12월 11일 18:26에 Marek Szyprowski 이(가) 쓴 글:
>>>
>>> Hi Inki,
>>>
>>> On 2015-12-11 10:02, Inki Dae wrote:
>>>>
>>>> Hi Marek,
>>>>
>>>> I found out why NULL point access happened. That was incurred by below
>>>> your patch,
>>>> [PATCH] drm/exynos: move dma_addr attribute from exynos plane to exynos
>>>> fb
>>>>
>>>> When another crtc driver is hotplugged in runtime such as HDMI or VIDI,
>>>> the drm frambuffer object of fb_helper is set to the plane state of the
>>>> new crtc driver
>>>> so the driver should get the drm framebuffer object from the plane's
>>>> state or
>>>> exynos_plane->pending_fb which is set by exynos_plane_atomic_update
>>>> function.
>>>>
>>>> After that, I think the drm framebuffer should be set to drm plane as a
>>>> current fb
>>>> which would be scanned out.
>>>>
>>>> Anyway, I can fix it like below if you are ok.
>>>>
>>>> Thanks,
>>>> Inki Dae
>>>>
>>>> --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>>> +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>>> @@ -137,7 +137,7 @@ static void vidi_update_plane(struct exynos_drm_crtc
>>>> *crtc,
>>>> if (ctx->suspended)
>>>> return;
>>>> - addr = exynos_drm_fb_dma_addr(plane->base.fb, 0);
>>>> + addr = exynos_drm_fb_dma_addr(plane->pending_fb, 0);
>>>> DRM_DEBUG_KMS("dma_addr = %pad\n", &addr);
>>>>
>>>> + plane->base.fb = plane->pending_fb;
>>>
>>> plane->base.fb should not be modified. I think that the following fix is
>>> more
>>
>> Could you explain why plane->base.fb shouldn't be modified?
>
>
> All 'base' classes are modified by DRM core and there should be no need
> to modify them from the drivers.
Ok, If so - drm core updates plane->fb - then it's reasonable. But I
couldn't find the exact location where plane->fb is set to a fb to be
scanned out.
So could you let me know the exact location? it's not clear to me yet.
>
> I've checked this issue and the proper fix for is the following code:
>
> --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
> @@ -131,13 +131,14 @@ static void vidi_disable_vblank(struct exynos_drm_crtc
> *crtc)
> static void vidi_update_plane(struct exynos_drm_crtc *crtc,
> struct exynos_drm_plane *plane)
> {
> + struct drm_plane_state *state = plane->base.state;
> struct vidi_context *ctx = crtc->ctx;
> dma_addr_t addr;
>
> if (ctx->suspended)
> return;
>
> - addr = exynos_drm_fb_dma_addr(plane->base.fb, 0);
> + addr = exynos_drm_fb_dma_addr(state->fb, 0);
> DRM_DEBUG_KMS("dma_addr = %pad\n", &addr);
>
> if (ctx->vblank_on)
>
>
> plane->base.fb is updated from the core once all crtc/plane atomic update
> calls finishes. The drivers should use the fb stored in plane->base.state.
> I've missed that VIDI driver doesn't get the fb and incorrectly used
> plane->base.fb instad of state->fb while updating the code.
>
Actually, I used state->fb instead of plane->pending_fb but in
exynos_plane_atomic_update function, plane->pending_fb is set to
state->fb.
That is why I commented like below,
" so the driver should get the drm framebuffer object from the plane's
state or exynos_plane->pending_fb which is set by
exynos_plane_atomic_update function."
Anyway, using state->fb looks like more consistent with other drivers,
fimd, decon and mixer.
Thanks,
Inki Dae
>
>
>> In case that userspace requests setplane, plane->base.fb would be updated
>> after update_plane callback.
>> However, in other cases, I don't see how plane->base.fb could be updated.
>> In this case, I think vendor specific drivers would need to update it as a
>> current fb to be scanned out like other some drivers did.
>> Of course, it may be possible for drm core part to take care of it
>> appropriately later.
>>
>> Thanks,
>> Inki Dae
>>
>>> appropriate:
>>> --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>> +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>> @@ -132,12 +132,13 @@ static void vidi_update_plane(struct
>>> exynos_drm_crtc *crtc,
>>> struct exynos_drm_plane *plane)
>>> {
>>> struct vidi_context *ctx = crtc->ctx;
>>> - dma_addr_t addr;
>>> + dma_addr_t addr = 0;
>>>
>>> if (ctx->suspended)
>>> return;
>>>
>>> - addr = exynos_drm_fb_dma_addr(plane->base.fb, 0);
>>> + if (plane->base.fb)
>>> + addr = exynos_drm_fb_dma_addr(plane->base.fb, 0);
>>> DRM_DEBUG_KMS("dma_addr = %pad\n", &addr);
>>>
>>> if (ctx->vblank_on)
>>>
>>> I will investigate the case of NULL plane->state.fb, because it might be
>>> relevant
>>> to other crtc drivers as well.
>>>
>>>
>>>> if (ctx->vblank_on)
>>>>
>>>>
>>>> 2015년 12월 10일 22:05에 Inki Dae 이(가) 쓴 글:
>>>>>
>>>>> 2015년 11월 30일 22:53에 Marek Szyprowski 이(가) 쓴 글:
>>>>>>
>>>>>> DMA address is a framebuffer attribute and the right place for it is
>>>>>> exynos_drm_framebuffer not exynos_drm_plane. This patch also
>>>>>> introduces
>>>>>> helper function for getting dma address of the given framebuffer.
>>>>>>
>>>>>> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
>>>>>> Reviewed-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
>>>>>> ---
>>>>>> drivers/gpu/drm/exynos/exynos5433_drm_decon.c | 13 ++++++++-----
>>>>>> drivers/gpu/drm/exynos/exynos7_drm_decon.c | 16 +++++++++-------
>>>>>> drivers/gpu/drm/exynos/exynos_drm_drv.h | 3 ---
>>>>>> drivers/gpu/drm/exynos/exynos_drm_fb.c | 16 ++++++----------
>>>>>> drivers/gpu/drm/exynos/exynos_drm_fb.h | 3 +--
>>>>>> drivers/gpu/drm/exynos/exynos_drm_fimd.c | 10 ++++++----
>>>>>> drivers/gpu/drm/exynos/exynos_drm_plane.c | 18
>>>>>> ------------------
>>>>>> drivers/gpu/drm/exynos/exynos_drm_vidi.c | 5 ++++-
>>>>>> drivers/gpu/drm/exynos/exynos_mixer.c | 7 ++++---
>>>>>> 9 files changed, 38 insertions(+), 53 deletions(-)
>>>>>>
>>>>> <--snip-->
>>>>>
>>>>>> diff --git a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>>>>> b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>>>>> index 669362c53f49..3ce141236fad 100644
>>>>>> --- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>>>>> +++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
>>>>>> @@ -24,6 +24,7 @@
>>>>>> #include "exynos_drm_drv.h"
>>>>>> #include "exynos_drm_crtc.h"
>>>>>> +#include "exynos_drm_fb.h"
>>>>>> #include "exynos_drm_plane.h"
>>>>>> #include "exynos_drm_vidi.h"
>>>>>> @@ -126,11 +127,13 @@ static void vidi_update_plane(struct
>>>>>> exynos_drm_crtc *crtc,
>>>>>> struct exynos_drm_plane *plane)
>>>>>> {
>>>>>> struct vidi_context *ctx = crtc->ctx;
>>>>>> + dma_addr_t addr;
>>>>>> if (ctx->suspended)
>>>>>> return;
>>>>>> - DRM_DEBUG_KMS("dma_addr = %pad\n", plane->dma_addr);
>>>>>> + addr = exynos_drm_fb_dma_addr(plane->base.fb, 0);
>>>>>
>>>>> At this point, plane->base.fb is NULL so null pointer access happens
>>>>> like below,
>>>>>
>>>>> [ 5.969422] Unable to handle kernel NULL pointer dereference at
>>>>> virtual address 00000090
>>>>> [ 5.977481] pgd = ee590000
>>>>> [ 5.980142] [00000090] *pgd=6e526831, *pte=00000000, *ppte=00000000
>>>>> [ 5.986347] Internal error: Oops: 17 [#1] PREEMPT SMP ARM
>>>>> [ 5.991712] Modules linked in:
>>>>> [ 5.994770] CPU: 3 PID: 1598 Comm: sh Not tainted
>>>>> 4.4.0-rc3-00052-gc60d7e2-dirty #199
>>>>> [ 6.002565] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
>>>>> [ 6.008647] task: ef328000 ti: ee4d4000 task.ti: ee4d4000
>>>>> [ 6.014053] PC is at exynos_drm_fb_dma_addr+0x8/0x14
>>>>> [ 6.018990] LR is at vidi_update_plane+0x4c/0xc4
>>>>> [ 6.023581] pc : [<c02b1fb4>] lr : [<c02c3cc4>] psr: 80000013
>>>>> [ 6.023581] sp : ee4d5d90 ip : 00000001 fp : 00000000
>>>>> [ 6.035029] r10: 00000000 r9 : c05b965c r8 : ee813e00
>>>>> [ 6.040241] r7 : 00000000 r6 : ee8e3330 r5 : 00000000 r4 :
>>>>> ee8e3010
>>>>> [ 6.046749] r3 : 00000000 r2 : 00000000 r1 : 00000024 r0 :
>>>>> 00000000
>>>>> [ 6.053264] Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM
>>>>> Segment none
>>>>> [ 6.060379] Control: 10c5387d Table: 6e59004a DAC: 00000051
>>>>> [ 6.066107] Process sh (pid: 1598, stack limit = 0xee4d4210)
>>>>> [ 6.071748] Stack: (0xee4d5d90 to 0xee4d6000)
>>>>> [ 6.076100] 5d80: 00000000
>>>>> ee813300 ee476e40 00000005
>>>>> [ 6.084236] 5da0: ee8e3330 c028ac14 00000008 ee476e40 ee476fc0
>>>>> ef3b3800 ee476fc0 eeb3e380
>>>>> [ 6.092395] 5dc0: 00000002 c02b08e4 00000000 eeb3e3a4 ee476fc0
>>>>> ee476e40 ef3b3800 eeb3e380
>>>>> [ 6.100554] 5de0: 00000002 c02b12b8 ee854400 00000000 00000001
>>>>> ee8501a8 00000000 ee476e40
>>>>> [ 6.108714] 5e00: ef3b3800 00000001 ee476e40 00000050 ee850c80
>>>>> 00000001 ee476e40 ef3b3aac
>>>>> [ 6.116873] 5e20: 00000002 000000ff 00000000 c028e0ec 000a82b4
>>>>> c02acc50 ee8e36a0 ee476c80
>>>>> [ 6.125032] 5e40: ef3b3aac ef3b3800 ee476c9c ee850c80 ef3b3800
>>>>> ef3b3800 ef3b3800 ef3b398c
>>>>> [ 6.133191] 5e60: c088c390 00000002 000a82b4 c028f8d4 00000000
>>>>> ef3b3800 ef0f4300 c028f948
>>>>> [ 6.141350] 5e80: ee850c80 c028f864 ef3b3a84 00000001 ef3b3a90
>>>>> c02853e4 00000001 00000000
>>>>> [ 6.149509] 5ea0: 000a82b4 ee4d5ec0 00000002 ee8e3010 00000002
>>>>> 00000002 ee4d5f88 00000000
>>>>> [ 6.157669] 5ec0: 00000000 eeb8df00 000a82b4 c02c4278 00000002
>>>>> ee476b00 eeb8df0c c01390ac
>>>>> [ 6.165828] 5ee0: 00000000 00000000 ee4e1f00 00000002 000a9540
>>>>> ee4d5f88 c000f844 ee4d4000
>>>>> [ 6.173987] 5f00: 00000000 c00dbf70 000a82b4 c00093dc ee4d4000
>>>>> ee4d5f78 ef328234 c0579bec
>>>>> [ 6.182146] 5f20: 00000001 00000001 ee4d5f3c 00000001 ee45e9c4
>>>>> 00000001 000a82b4 c005ca74
>>>>> [ 6.190306] 5f40: ee45e9c4 00000002 000a9540 c005cad4 ee4e1f00
>>>>> 00000002 000a9540 ee4d5f88
>>>>> [ 6.198465] 5f60: c000f844 c00dc770 00000000 00000000 ee4e1f00
>>>>> ee4e1f00 00000002 000a9540
>>>>> [ 6.206624] 5f80: c000f844 c00dcf98 00000000 00000000 00000003
>>>>> 000a7c40 00000001 000a9540
>>>>> [ 6.214783] 5fa0: 00000004 c000f680 000a7c40 00000001 00000001
>>>>> 000a9540 00000002 00000000
>>>>> [ 6.222942] 5fc0: 000a7c40 00000001 000a9540 00000004 00000020
>>>>> 000a82c8 000a8294 000a82b4
>>>>> [ 6.231102] 5fe0: 00000000 be8b1624 00012345 b6e94166 40000030
>>>>> 00000001 00000000 00000000
>>>>> [ 6.239270] [<c02b1fb4>] (exynos_drm_fb_dma_addr) from [<c02c3cc4>]
>>>>> (vidi_update_plane+0x4c/0xc4)
>>>>> [ 6.248122] [<c02c3cc4>] (vidi_update_plane) from [<c028ac14>]
>>>>> (drm_atomic_helper_commit_planes+0x1f4/0x258)
>>>>> [ 6.257928] [<c028ac14>] (drm_atomic_helper_commit_planes) from
>>>>> [<c02b08e4>] (exynos_atomic_commit_complete+0xe4/0x1c4)
>>>>> [ 6.268688] [<c02b08e4>] (exynos_atomic_commit_complete) from
>>>>> [<c02b12b8>] (exynos_atomic_commit+0x180/0x1cc)
>>>>> [ 6.278584] [<c02b12b8>] (exynos_atomic_commit) from [<c028e0ec>]
>>>>> (restore_fbdev_mode+0x260/0x290)
>>>>> [ 6.287525] [<c028e0ec>] (restore_fbdev_mode) from [<c028f8d4>]
>>>>> (drm_fb_helper_restore_fbdev_mode_unlocked+0x30/0x74)
>>>>> [ 6.298111] [<c028f8d4>] (drm_fb_helper_restore_fbdev_mode_unlocked)
>>>>> from [<c028f948>] (drm_fb_helper_set_par+0x30/0x54)
>>>>> [ 6.308961] [<c028f948>] (drm_fb_helper_set_par) from [<c028f864>]
>>>>> (drm_fb_helper_hotplug_event+0x9c/0xdc)
>>>>> [ 6.318595] [<c028f864>] (drm_fb_helper_hotplug_event) from
>>>>> [<c02853e4>] (drm_helper_hpd_irq_event+0xd4/0x160)
>>>>> [ 6.328578] [<c02853e4>] (drm_helper_hpd_irq_event) from
>>>>> [<c02c4278>] (vidi_store_connection+0x94/0xcc)
>>>>> [ 6.337954] [<c02c4278>] (vidi_store_connection) from [<c01390ac>]
>>>>> (kernfs_fop_write+0xb8/0x1bc)
>>>>> [ 6.346723] [<c01390ac>] (kernfs_fop_write) from [<c00dbf70>]
>>>>> (__vfs_write+0x20/0xd8)
>>>>> [ 6.354531] [<c00dbf70>] (__vfs_write) from [<c00dc770>]
>>>>> (vfs_write+0x90/0x164)
>>>>> [ 6.361821] [<c00dc770>] (vfs_write) from [<c00dcf98>]
>>>>> (SyS_write+0x44/0x9c)
>>>>> [ 6.368855] [<c00dcf98>] (SyS_write) from [<c000f680>]
>>>>> (ret_fast_syscall+0x0/0x3c)
>>>>> [ 6.376404] Code: eb0b17f1 eaffffe7 e3510003 d2811024 (d7900101)
>>>>>
>>>>> When vidi driver is intiated by triggering a connection sysfs file,
>>>>> vidi driver tries modeset binding by calling drm_fb_helper_hotplug_event.
>>>>> However, at this time it seems there is a case that plan->state->crtc
>>>>> exists but plane->fb is NULL, which would be related to vidi driver.
>>>>>
>>>>> I just looked into this issue roughly so we would need to check this
>>>>> issue in more details.
>>>>>
>>>>> Thanks,
>>>>> Inki Dae
>>>>>
>>>>>> + DRM_DEBUG_KMS("dma_addr = %pad\n", &addr);
>>>>>> if (ctx->vblank_on)
>>>>>> schedule_work(&ctx->work);
>>>>>> diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c
>>>>>> b/drivers/gpu/drm/exynos/exynos_mixer.c
>>>>>> index 47777be1a754..f40de82848dc 100644
>>>>>> --- a/drivers/gpu/drm/exynos/exynos_mixer.c
>>>>>> +++ b/drivers/gpu/drm/exynos/exynos_mixer.c
>>>>>> @@ -37,6 +37,7 @@
>>>>>> #include "exynos_drm_drv.h"
>>>>>> #include "exynos_drm_crtc.h"
>>>>>> +#include "exynos_drm_fb.h"
>>>>>> #include "exynos_drm_plane.h"
>>>>>> #include "exynos_drm_iommu.h"
>>>>>> @@ -422,8 +423,8 @@ static void vp_video_buffer(struct
>>>>>> mixer_context *ctx,
>>>>>> return;
>>>>>> }
>>>>>> - luma_addr[0] = plane->dma_addr[0];
>>>>>> - chroma_addr[0] = plane->dma_addr[1];
>>>>>> + luma_addr[0] = exynos_drm_fb_dma_addr(fb, 0);
>>>>>> + chroma_addr[0] = exynos_drm_fb_dma_addr(fb, 1);
>>>>>> if (mode->flags & DRM_MODE_FLAG_INTERLACE) {
>>>>>> ctx->interlace = true;
>>>>>> @@ -575,7 +576,7 @@ static void mixer_graph_buffer(struct
>>>>>> mixer_context *ctx,
>>>>>> dst_y_offset = plane->crtc_y;
>>>>>> /* converting dma address base and source offset */
>>>>>> - dma_addr = plane->dma_addr[0]
>>>>>> + dma_addr = exynos_drm_fb_dma_addr(fb, 0)
>>>>>> + (plane->src_x * fb->bits_per_pixel >> 3)
>>>>>> + (plane->src_y * fb->pitches[0]);
>>>>>> src_x_offset = 0;
>>>>>>
>>>>>>
>>>>>>
>
> Best regards
> --
> Marek Szyprowski, PhD
> Samsung R&D Institute Poland
>
> _______________________________________________
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> dri-devel@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
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