| Message ID | 20240604080328.4024838-1-peng.fan@oss.nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/fbdev-dma: fix getting smem_start | expand |
Hi Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): > From: Peng Fan <peng.fan@nxp.com> > > If 'info->screen_buffer' locates in vmalloc address space, virt_to_page > will not be able to get correct results. With CONFIG_DEBUG_VM and > CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: Which graphics driver triggers this bug? > [ 3.536043] ------------[ cut here ]------------ > [ 3.540716] virt_to_phys used for non-linear address: 000000007fc4f540 (0xffff800086001000) > [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 __virt_to_phys+0x68/0x98 > [ 3.565455] Modules linked in: > [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted 6.6.23-06226-g4986cc3e1b75-dirty #250 > [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) > [ 3.582452] Workqueue: events_unbound deferred_probe_work_func > [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 3.595233] pc : __virt_to_phys+0x68/0x98 > [ 3.599246] lr : __virt_to_phys+0x68/0x98 > [ 3.603276] sp : ffff800083603990 > [ 3.677939] Call trace: > [ 3.680393] __virt_to_phys+0x68/0x98 > [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 > [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 > [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 > [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 > [ 3.705161] drm_client_register+0x60/0xb0 > [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 > > So add a check 'is_vmalloc_addr'. > > Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for GEM DMA helpers") > Signed-off-by: Peng Fan <peng.fan@nxp.com> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> Best regards Thomas > --- > drivers/gpu/drm/drm_fbdev_dma.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_fbdev_dma.c b/drivers/gpu/drm/drm_fbdev_dma.c > index 6c9427bb4053..9e2eddb6eb5c 100644 > --- a/drivers/gpu/drm/drm_fbdev_dma.c > +++ b/drivers/gpu/drm/drm_fbdev_dma.c > @@ -130,7 +130,12 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper, > info->flags |= FBINFO_READS_FAST; /* signal caching */ > info->screen_size = sizes->surface_height * fb->pitches[0]; > info->screen_buffer = map.vaddr; > - info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer)); > + > + if (is_vmalloc_addr(info->screen_buffer)) > + info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer)); > + else > + info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer)); > + > info->fix.smem_len = info->screen_size; > > return 0;
> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start > > Hi > > Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): > > From: Peng Fan <peng.fan@nxp.com> > > > > If 'info->screen_buffer' locates in vmalloc address space, > > virt_to_page will not be able to get correct results. With > > CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64, > there is dump below: > > Which graphics driver triggers this bug? It is NXP i.MX95 DPU driver which is still in NXP downstream repo. Thanks, Peng.
Hi Am 11.06.24 um 03:00 schrieb Peng Fan: >> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start >> >> Hi >> >> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>> From: Peng Fan <peng.fan@nxp.com> >>> >>> If 'info->screen_buffer' locates in vmalloc address space, >>> virt_to_page will not be able to get correct results. With >>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64, >> there is dump below: >> >> Which graphics driver triggers this bug? > It is NXP i.MX95 DPU driver which is still in NXP downstream repo. Which DRM memory manager does that driver use? I'm asking because if the driver allocates BOs via vmalloc(), should it really use fbdev-dma? Best regards Thomas > > Thanks, > Peng.
> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start > > Hi > > Am 11.06.24 um 03:00 schrieb Peng Fan: > >> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start > >> > >> Hi > >> > >> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): > >>> From: Peng Fan <peng.fan@nxp.com> > >>> > >>> If 'info->screen_buffer' locates in vmalloc address space, > >>> virt_to_page will not be able to get correct results. With > >>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64, > >> there is dump below: > >> > >> Which graphics driver triggers this bug? > > It is NXP i.MX95 DPU driver which is still in NXP downstream repo. > > Which DRM memory manager does that driver use? DRM_GEM_DMA_DRIVER_OPS > > I'm asking because if the driver allocates BOs via vmalloc(), should it really > use fbdev-dma? We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0, fbdev emulation could be disabled. Thanks Peng > > Best regards > Thomas > > > > > Thanks, > > Peng. > > -- > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Frankenstrasse 146, 90461 Nuernberg, Germany > GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB > 36809 (AG Nuernberg)
Hi Am 11.06.24 um 10:23 schrieb Peng Fan: >> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start >> >> Hi >> >> Am 11.06.24 um 03:00 schrieb Peng Fan: >>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start >>>> >>>> Hi >>>> >>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>>>> From: Peng Fan <peng.fan@nxp.com> >>>>> >>>>> If 'info->screen_buffer' locates in vmalloc address space, >>>>> virt_to_page will not be able to get correct results. With >>>>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64, >>>> there is dump below: >>>> >>>> Which graphics driver triggers this bug? >>> It is NXP i.MX95 DPU driver which is still in NXP downstream repo. >> Which DRM memory manager does that driver use? > DRM_GEM_DMA_DRIVER_OPS So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't you allocate from one of these dma_alloc_() calls at [1] ? How does the drivers end up with vmalloc'd fbdev memory? Specifically in the light of the docs at [2]. [1] https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146 [2] https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124 Best regards Thomas > >> I'm asking because if the driver allocates BOs via vmalloc(), should it really >> use fbdev-dma? > We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0, > fbdev emulation could be disabled. > > Thanks > Peng >> Best regards >> Thomas >> >>> Thanks, >>> Peng. >> -- >> -- >> Thomas Zimmermann >> Graphics Driver Developer >> SUSE Software Solutions Germany GmbH >> Frankenstrasse 146, 90461 Nuernberg, Germany >> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB >> 36809 (AG Nuernberg)
Hi Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: > Hi > > Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >> From: Peng Fan <peng.fan@nxp.com> >> >> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page >> will not be able to get correct results. With CONFIG_DEBUG_VM and >> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: > > Which graphics driver triggers this bug? > >> [ 3.536043] ------------[ cut here ]------------ >> [ 3.540716] virt_to_phys used for non-linear address: >> 000000007fc4f540 (0xffff800086001000) >> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 >> __virt_to_phys+0x68/0x98 >> [ 3.565455] Modules linked in: >> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted >> 6.6.23-06226-g4986cc3e1b75-dirty #250 >> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) >> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func >> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS >> BTYPE=--) >> [ 3.595233] pc : __virt_to_phys+0x68/0x98 >> [ 3.599246] lr : __virt_to_phys+0x68/0x98 >> [ 3.603276] sp : ffff800083603990 >> [ 3.677939] Call trace: >> [ 3.680393] __virt_to_phys+0x68/0x98 >> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 >> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 >> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 >> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 >> [ 3.705161] drm_client_register+0x60/0xb0 >> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 >> >> So add a check 'is_vmalloc_addr'. >> >> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for >> GEM DMA helpers") >> Signed-off-by: Peng Fan <peng.fan@nxp.com> > > Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> I'm taking back my r-b. The memory is expected to by be physically contiguous and vmalloc() won't guarantee that. Best regards Thomas > > Best regards > Thomas > >> --- >> drivers/gpu/drm/drm_fbdev_dma.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/drm_fbdev_dma.c >> b/drivers/gpu/drm/drm_fbdev_dma.c >> index 6c9427bb4053..9e2eddb6eb5c 100644 >> --- a/drivers/gpu/drm/drm_fbdev_dma.c >> +++ b/drivers/gpu/drm/drm_fbdev_dma.c >> @@ -130,7 +130,12 @@ static int drm_fbdev_dma_helper_fb_probe(struct >> drm_fb_helper *fb_helper, >> info->flags |= FBINFO_READS_FAST; /* signal caching */ >> info->screen_size = sizes->surface_height * fb->pitches[0]; >> info->screen_buffer = map.vaddr; >> - info->fix.smem_start = >> page_to_phys(virt_to_page(info->screen_buffer)); >> + >> + if (is_vmalloc_addr(info->screen_buffer)) >> + info->fix.smem_start = >> page_to_phys(vmalloc_to_page(info->screen_buffer)); >> + else >> + info->fix.smem_start = >> page_to_phys(virt_to_page(info->screen_buffer)); >> + >> info->fix.smem_len = info->screen_size; >> return 0; >
Thomas Zimmermann <tzimmermann@suse.de> writes: Hello Thomas, > Hi > > Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: >> Hi >> >> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>> From: Peng Fan <peng.fan@nxp.com> >>> >>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page >>> will not be able to get correct results. With CONFIG_DEBUG_VM and >>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: >> >> Which graphics driver triggers this bug? >> >>> [ 3.536043] ------------[ cut here ]------------ >>> [ 3.540716] virt_to_phys used for non-linear address: >>> 000000007fc4f540 (0xffff800086001000) >>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 >>> __virt_to_phys+0x68/0x98 >>> [ 3.565455] Modules linked in: >>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted >>> 6.6.23-06226-g4986cc3e1b75-dirty #250 >>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) >>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func >>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS >>> BTYPE=--) >>> [ 3.595233] pc : __virt_to_phys+0x68/0x98 >>> [ 3.599246] lr : __virt_to_phys+0x68/0x98 >>> [ 3.603276] sp : ffff800083603990 >>> [ 3.677939] Call trace: >>> [ 3.680393] __virt_to_phys+0x68/0x98 >>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 >>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 >>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 >>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 >>> [ 3.705161] drm_client_register+0x60/0xb0 >>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 >>> >>> So add a check 'is_vmalloc_addr'. >>> >>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for >>> GEM DMA helpers") >>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >> >> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> > > I'm taking back my r-b. The memory is expected to by be physically > contiguous and vmalloc() won't guarantee that. > Agreed. > Best regards > Thomas >
Hi Javier Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas: > Thomas Zimmermann <tzimmermann@suse.de> writes: > > Hello Thomas, > >> Hi >> >> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: >>> Hi >>> >>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>>> From: Peng Fan <peng.fan@nxp.com> >>>> >>>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page >>>> will not be able to get correct results. With CONFIG_DEBUG_VM and >>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: >>> Which graphics driver triggers this bug? >>> >>>> [ 3.536043] ------------[ cut here ]------------ >>>> [ 3.540716] virt_to_phys used for non-linear address: >>>> 000000007fc4f540 (0xffff800086001000) >>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 >>>> __virt_to_phys+0x68/0x98 >>>> [ 3.565455] Modules linked in: >>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted >>>> 6.6.23-06226-g4986cc3e1b75-dirty #250 >>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) >>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func >>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS >>>> BTYPE=--) >>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98 >>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98 >>>> [ 3.603276] sp : ffff800083603990 >>>> [ 3.677939] Call trace: >>>> [ 3.680393] __virt_to_phys+0x68/0x98 >>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 >>>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 >>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 >>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 >>>> [ 3.705161] drm_client_register+0x60/0xb0 >>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 >>>> >>>> So add a check 'is_vmalloc_addr'. >>>> >>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for >>>> GEM DMA helpers") >>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >>> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> >> I'm taking back my r-b. The memory is expected to by be physically >> contiguous and vmalloc() won't guarantee that. >> > Agreed. These smem_ fields are clearly designed for PCI BARs of traditional graphics cards. So can we even assume contiguous memory for DMA? That was my assumption, but with IOMMUs it might not be the case. Fbdev-dma only sets smem_start to support a single old userspace driver. Maybe we should further restrict usage of this field by making it opt-in for each driver. Best regards Thomas > >> Best regards >> Thomas >>
On Tue, Jun 11, 2024 at 11:29:58AM +0200, Thomas Zimmermann wrote: > Hi > > Am 11.06.24 um 10:23 schrieb Peng Fan: > > > Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start > > > > > > Hi > > > > > > Am 11.06.24 um 03:00 schrieb Peng Fan: > > > > > Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start > > > > > > > > > > Hi > > > > > > > > > > Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): > > > > > > From: Peng Fan <peng.fan@nxp.com> > > > > > > > > > > > > If 'info->screen_buffer' locates in vmalloc address space, > > > > > > virt_to_page will not be able to get correct results. With > > > > > > CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64, > > > > > there is dump below: > > > > > > > > > > Which graphics driver triggers this bug? > > > > It is NXP i.MX95 DPU driver which is still in NXP downstream repo. > > > Which DRM memory manager does that driver use? > > DRM_GEM_DMA_DRIVER_OPS > > So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't you > allocate from one of these dma_alloc_() calls at [1] ? How does the drivers > end up with vmalloc'd fbdev memory? Specifically in the light of the docs at > [2]. I think when you have an iommu dma_alloc just allocates pages, and uses the iommu to make it all contiguous for the device, and vmalloc for the kernel. So it's not allocated with vmalloc(), just ends up getting mapped into the vmalloc range. -Sima > > [1] https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146 > [2] https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124 > > Best regards > Thomas > > > > > > I'm asking because if the driver allocates BOs via vmalloc(), should it really > > > use fbdev-dma? > > We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0, > > fbdev emulation could be disabled. > > > > Thanks > > Peng > > > Best regards > > > Thomas > > > > > > > Thanks, > > > > Peng. > > > -- > > > -- > > > Thomas Zimmermann > > > Graphics Driver Developer > > > SUSE Software Solutions Germany GmbH > > > Frankenstrasse 146, 90461 Nuernberg, Germany > > > GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB > > > 36809 (AG Nuernberg) > > -- > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Frankenstrasse 146, 90461 Nuernberg, Germany > GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman > HRB 36809 (AG Nuernberg) >
Hi Am 12.06.24 um 10:45 schrieb Daniel Vetter: > On Tue, Jun 11, 2024 at 11:29:58AM +0200, Thomas Zimmermann wrote: >> Hi >> >> Am 11.06.24 um 10:23 schrieb Peng Fan: >>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start >>>> >>>> Hi >>>> >>>> Am 11.06.24 um 03:00 schrieb Peng Fan: >>>>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start >>>>>> >>>>>> Hi >>>>>> >>>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>>>>>> From: Peng Fan <peng.fan@nxp.com> >>>>>>> >>>>>>> If 'info->screen_buffer' locates in vmalloc address space, >>>>>>> virt_to_page will not be able to get correct results. With >>>>>>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64, >>>>>> there is dump below: >>>>>> >>>>>> Which graphics driver triggers this bug? >>>>> It is NXP i.MX95 DPU driver which is still in NXP downstream repo. >>>> Which DRM memory manager does that driver use? >>> DRM_GEM_DMA_DRIVER_OPS >> So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't you >> allocate from one of these dma_alloc_() calls at [1] ? How does the drivers >> end up with vmalloc'd fbdev memory? Specifically in the light of the docs at >> [2]. > I think when you have an iommu dma_alloc just allocates pages, and uses > the iommu to make it all contiguous for the device, and vmalloc for the > kernel. So it's not allocated with vmalloc(), just ends up getting mapped > into the vmalloc range. Thanks, that makes sense. As I mentioned in another reply, it might make sense to protect smem_start with an opt-in flag for only that single driver that needs it. Best regards Thomas > -Sima > > >> [1] https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146 >> [2] https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124 >> >> Best regards >> Thomas >> >>>> I'm asking because if the driver allocates BOs via vmalloc(), should it really >>>> use fbdev-dma? >>> We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0, >>> fbdev emulation could be disabled. >>> >>> Thanks >>> Peng >>>> Best regards >>>> Thomas >>>> >>>>> Thanks, >>>>> Peng. >>>> -- >>>> -- >>>> Thomas Zimmermann >>>> Graphics Driver Developer >>>> SUSE Software Solutions Germany GmbH >>>> Frankenstrasse 146, 90461 Nuernberg, Germany >>>> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB >>>> 36809 (AG Nuernberg) >> -- >> -- >> Thomas Zimmermann >> Graphics Driver Developer >> SUSE Software Solutions Germany GmbH >> Frankenstrasse 146, 90461 Nuernberg, Germany >> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman >> HRB 36809 (AG Nuernberg) >>
On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote: > Hi Javier > > Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas: > > Thomas Zimmermann <tzimmermann@suse.de> writes: > > > > Hello Thomas, > > > > > Hi > > > > > > Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: > > > > Hi > > > > > > > > Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): > > > > > From: Peng Fan <peng.fan@nxp.com> > > > > > > > > > > If 'info->screen_buffer' locates in vmalloc address space, virt_to_page > > > > > will not be able to get correct results. With CONFIG_DEBUG_VM and > > > > > CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: > > > > Which graphics driver triggers this bug? > > > > > > > > > [ 3.536043] ------------[ cut here ]------------ > > > > > [ 3.540716] virt_to_phys used for non-linear address: > > > > > 000000007fc4f540 (0xffff800086001000) > > > > > [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 > > > > > __virt_to_phys+0x68/0x98 > > > > > [ 3.565455] Modules linked in: > > > > > [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted > > > > > 6.6.23-06226-g4986cc3e1b75-dirty #250 > > > > > [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) > > > > > [ 3.582452] Workqueue: events_unbound deferred_probe_work_func > > > > > [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS > > > > > BTYPE=--) > > > > > [ 3.595233] pc : __virt_to_phys+0x68/0x98 > > > > > [ 3.599246] lr : __virt_to_phys+0x68/0x98 > > > > > [ 3.603276] sp : ffff800083603990 > > > > > [ 3.677939] Call trace: > > > > > [ 3.680393] __virt_to_phys+0x68/0x98 > > > > > [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 > > > > > [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 > > > > > [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 > > > > > [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 > > > > > [ 3.705161] drm_client_register+0x60/0xb0 > > > > > [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 > > > > > > > > > > So add a check 'is_vmalloc_addr'. > > > > > > > > > > Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for > > > > > GEM DMA helpers") > > > > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > > > > Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> > > > I'm taking back my r-b. The memory is expected to by be physically > > > contiguous and vmalloc() won't guarantee that. > > > > > Agreed. > > These smem_ fields are clearly designed for PCI BARs of traditional graphics > cards. So can we even assume contiguous memory for DMA? That was my > assumption, but with IOMMUs it might not be the case. Fbdev-dma only sets > smem_start to support a single old userspace driver. Maybe we should further > restrict usage of this field by making it opt-in for each driver. Best > regards Thomas We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is that with the old fb_mmap code we had to always fill out smem_start to make mmap work. But now that the various drm fbdev helpers have all their own mmap implementation, we could make this a lot cleaner. If I haven't missed anything, that is. -Sima
Hi Am 12.06.24 um 17:00 schrieb Daniel Vetter: > On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote: >> Hi Javier >> >> Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas: >>> Thomas Zimmermann <tzimmermann@suse.de> writes: >>> >>> Hello Thomas, >>> >>>> Hi >>>> >>>> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: >>>>> Hi >>>>> >>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>>>>> From: Peng Fan <peng.fan@nxp.com> >>>>>> >>>>>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page >>>>>> will not be able to get correct results. With CONFIG_DEBUG_VM and >>>>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: >>>>> Which graphics driver triggers this bug? >>>>> >>>>>> [ 3.536043] ------------[ cut here ]------------ >>>>>> [ 3.540716] virt_to_phys used for non-linear address: >>>>>> 000000007fc4f540 (0xffff800086001000) >>>>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 >>>>>> __virt_to_phys+0x68/0x98 >>>>>> [ 3.565455] Modules linked in: >>>>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted >>>>>> 6.6.23-06226-g4986cc3e1b75-dirty #250 >>>>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) >>>>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func >>>>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS >>>>>> BTYPE=--) >>>>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98 >>>>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98 >>>>>> [ 3.603276] sp : ffff800083603990 >>>>>> [ 3.677939] Call trace: >>>>>> [ 3.680393] __virt_to_phys+0x68/0x98 >>>>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 >>>>>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 >>>>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 >>>>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 >>>>>> [ 3.705161] drm_client_register+0x60/0xb0 >>>>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 >>>>>> >>>>>> So add a check 'is_vmalloc_addr'. >>>>>> >>>>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for >>>>>> GEM DMA helpers") >>>>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >>>>> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> >>>> I'm taking back my r-b. The memory is expected to by be physically >>>> contiguous and vmalloc() won't guarantee that. >>>> >>> Agreed. >> These smem_ fields are clearly designed for PCI BARs of traditional graphics >> cards. So can we even assume contiguous memory for DMA? That was my >> assumption, but with IOMMUs it might not be the case. Fbdev-dma only sets >> smem_start to support a single old userspace driver. Maybe we should further >> restrict usage of this field by making it opt-in for each driver. Best >> regards Thomas > We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and > remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is > that with the old fb_mmap code we had to always fill out smem_start to > make mmap work. But now that the various drm fbdev helpers have all their > own mmap implementation, we could make this a lot cleaner. Enabling CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM would still crash the NXP driver. I think I'll add a flag to drm_fbdev_dma_setup() to set smem_start from within lima, which is the only driver that requires it.I'd like to remove CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM and all that, but I fear that it would break someone's setup. Best regards Thomas > > If I haven't missed anything, that is. > -Sima
Hi Am 13.06.24 um 12:14 schrieb Thomas Zimmermann: > Hi > > Am 12.06.24 um 17:00 schrieb Daniel Vetter: >> On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote: >>> Hi Javier >>> >>> Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas: >>>> Thomas Zimmermann <tzimmermann@suse.de> writes: >>>> >>>> Hello Thomas, >>>> >>>>> Hi >>>>> >>>>> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: >>>>>> Hi >>>>>> >>>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>>>>>> From: Peng Fan <peng.fan@nxp.com> >>>>>>> >>>>>>> If 'info->screen_buffer' locates in vmalloc address space, >>>>>>> virt_to_page >>>>>>> will not be able to get correct results. With CONFIG_DEBUG_VM and >>>>>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: >>>>>> Which graphics driver triggers this bug? >>>>>> >>>>>>> [ 3.536043] ------------[ cut here ]------------ >>>>>>> [ 3.540716] virt_to_phys used for non-linear address: >>>>>>> 000000007fc4f540 (0xffff800086001000) >>>>>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at >>>>>>> arch/arm64/mm/physaddr.c:12 >>>>>>> __virt_to_phys+0x68/0x98 >>>>>>> [ 3.565455] Modules linked in: >>>>>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted >>>>>>> 6.6.23-06226-g4986cc3e1b75-dirty #250 >>>>>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) >>>>>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func >>>>>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT >>>>>>> -SSBS >>>>>>> BTYPE=--) >>>>>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98 >>>>>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98 >>>>>>> [ 3.603276] sp : ffff800083603990 >>>>>>> [ 3.677939] Call trace: >>>>>>> [ 3.680393] __virt_to_phys+0x68/0x98 >>>>>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 >>>>>>> [ 3.689214] >>>>>>> __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 >>>>>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 >>>>>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 >>>>>>> [ 3.705161] drm_client_register+0x60/0xb0 >>>>>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 >>>>>>> >>>>>>> So add a check 'is_vmalloc_addr'. >>>>>>> >>>>>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for >>>>>>> GEM DMA helpers") >>>>>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >>>>>> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> >>>>> I'm taking back my r-b. The memory is expected to by be physically >>>>> contiguous and vmalloc() won't guarantee that. >>>>> >>>> Agreed. >>> These smem_ fields are clearly designed for PCI BARs of traditional >>> graphics >>> cards. So can we even assume contiguous memory for DMA? That was my >>> assumption, but with IOMMUs it might not be the case. Fbdev-dma only >>> sets >>> smem_start to support a single old userspace driver. Maybe we should >>> further >>> restrict usage of this field by making it opt-in for each driver. Best >>> regards Thomas >> We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and >> remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is >> that with the old fb_mmap code we had to always fill out smem_start to >> make mmap work. But now that the various drm fbdev helpers have all >> their >> own mmap implementation, we could make this a lot cleaner. > > Enabling CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM would still crash the NXP > driver. I think I'll add a flag to drm_fbdev_dma_setup() to set > smem_start from within lima, which is the only driver that requires > it.I'd like to remove CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM and all that, > but I fear that it would break someone's setup. Best regards Thomas I've been looking at https://lore.kernel.org/dri-devel/20240318-dark-mongoose-of-camouflage-7ac6ed@houat/ and I'm now confused to find that lima doesn't even set up fbdev support. Best regards Thomas >> >> If I haven't missed anything, that is. >> -Sima >
On Thu, Jun 13, 2024 at 12:18:55PM +0200, Thomas Zimmermann wrote: > Hi > > Am 13.06.24 um 12:14 schrieb Thomas Zimmermann: > > Hi > > > > Am 12.06.24 um 17:00 schrieb Daniel Vetter: > > > On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote: > > > > Hi Javier > > > > > > > > Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas: > > > > > Thomas Zimmermann <tzimmermann@suse.de> writes: > > > > > > > > > > Hello Thomas, > > > > > > > > > > > Hi > > > > > > > > > > > > Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: > > > > > > > Hi > > > > > > > > > > > > > > Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): > > > > > > > > From: Peng Fan <peng.fan@nxp.com> > > > > > > > > > > > > > > > > If 'info->screen_buffer' locates in vmalloc > > > > > > > > address space, virt_to_page > > > > > > > > will not be able to get correct results. With CONFIG_DEBUG_VM and > > > > > > > > CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: > > > > > > > Which graphics driver triggers this bug? > > > > > > > > > > > > > > > [ 3.536043] ------------[ cut here ]------------ > > > > > > > > [ 3.540716] virt_to_phys used for non-linear address: > > > > > > > > 000000007fc4f540 (0xffff800086001000) > > > > > > > > [ 3.552628] WARNING: CPU: 4 PID: 61 at > > > > > > > > arch/arm64/mm/physaddr.c:12 > > > > > > > > __virt_to_phys+0x68/0x98 > > > > > > > > [ 3.565455] Modules linked in: > > > > > > > > [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted > > > > > > > > 6.6.23-06226-g4986cc3e1b75-dirty #250 > > > > > > > > [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) > > > > > > > > [ 3.582452] Workqueue: events_unbound deferred_probe_work_func > > > > > > > > [ 3.588291] pstate: 60400009 (nZCv daif +PAN > > > > > > > > -UAO -TCO -DIT -SSBS > > > > > > > > BTYPE=--) > > > > > > > > [ 3.595233] pc : __virt_to_phys+0x68/0x98 > > > > > > > > [ 3.599246] lr : __virt_to_phys+0x68/0x98 > > > > > > > > [ 3.603276] sp : ffff800083603990 > > > > > > > > [ 3.677939] Call trace: > > > > > > > > [ 3.680393] __virt_to_phys+0x68/0x98 > > > > > > > > [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 > > > > > > > > [ 3.689214] > > > > > > > > __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 > > > > > > > > [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 > > > > > > > > [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 > > > > > > > > [ 3.705161] drm_client_register+0x60/0xb0 > > > > > > > > [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 > > > > > > > > > > > > > > > > So add a check 'is_vmalloc_addr'. > > > > > > > > > > > > > > > > Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for > > > > > > > > GEM DMA helpers") > > > > > > > > Signed-off-by: Peng Fan <peng.fan@nxp.com> > > > > > > > Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> > > > > > > I'm taking back my r-b. The memory is expected to by be physically > > > > > > contiguous and vmalloc() won't guarantee that. > > > > > > > > > > > Agreed. > > > > These smem_ fields are clearly designed for PCI BARs of > > > > traditional graphics > > > > cards. So can we even assume contiguous memory for DMA? That was my > > > > assumption, but with IOMMUs it might not be the case. Fbdev-dma > > > > only sets > > > > smem_start to support a single old userspace driver. Maybe we > > > > should further > > > > restrict usage of this field by making it opt-in for each driver. Best > > > > regards Thomas > > > We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and > > > remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is > > > that with the old fb_mmap code we had to always fill out smem_start to > > > make mmap work. But now that the various drm fbdev helpers have all > > > their > > > own mmap implementation, we could make this a lot cleaner. > > > > Enabling CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM would still crash the NXP > > driver. I think I'll add a flag to drm_fbdev_dma_setup() to set > > smem_start from within lima, which is the only driver that requires > > it.I'd like to remove CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM and all that, but > > I fear that it would break someone's setup. Best regards Thomas Yeah we'd always need to make this conditional on the memory not being in the vmalloc range, or things will blow up. > I've been looking at > > https://lore.kernel.org/dri-devel/20240318-dark-mongoose-of-camouflage-7ac6ed@houat/ > > and I'm now confused to find that lima doesn't even set up fbdev support. The mali driver here was the out-of-tree proprietary mali driver as the consumer of such buffers. The "exporters" was just any random fbdev driver, and with the DRM option to set the smem, also drm drivers could play in this role. It at least seems to have helped a few people to move away from out-of-tree fbdev drivers to upstream drm drivers (but still with the out-of-tree mali gpu driver). Which means we've needed this for any display driver that happens to have shipped together with one of these older mali gpus. It's a bit a mess, and it might indeed have outlived it's usefulness. Cheers, Sima
Hi Am 17.06.24 um 16:04 schrieb Daniel Vetter: > On Thu, Jun 13, 2024 at 12:18:55PM +0200, Thomas Zimmermann wrote: >> Hi >> >> Am 13.06.24 um 12:14 schrieb Thomas Zimmermann: >>> Hi >>> >>> Am 12.06.24 um 17:00 schrieb Daniel Vetter: >>>> On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote: >>>>> Hi Javier >>>>> >>>>> Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas: >>>>>> Thomas Zimmermann <tzimmermann@suse.de> writes: >>>>>> >>>>>> Hello Thomas, >>>>>> >>>>>>> Hi >>>>>>> >>>>>>> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann: >>>>>>>> Hi >>>>>>>> >>>>>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS): >>>>>>>>> From: Peng Fan <peng.fan@nxp.com> >>>>>>>>> >>>>>>>>> If 'info->screen_buffer' locates in vmalloc >>>>>>>>> address space, virt_to_page >>>>>>>>> will not be able to get correct results. With CONFIG_DEBUG_VM and >>>>>>>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below: >>>>>>>> Which graphics driver triggers this bug? >>>>>>>> >>>>>>>>> [ 3.536043] ------------[ cut here ]------------ >>>>>>>>> [ 3.540716] virt_to_phys used for non-linear address: >>>>>>>>> 000000007fc4f540 (0xffff800086001000) >>>>>>>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at >>>>>>>>> arch/arm64/mm/physaddr.c:12 >>>>>>>>> __virt_to_phys+0x68/0x98 >>>>>>>>> [ 3.565455] Modules linked in: >>>>>>>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted >>>>>>>>> 6.6.23-06226-g4986cc3e1b75-dirty #250 >>>>>>>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) >>>>>>>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func >>>>>>>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN >>>>>>>>> -UAO -TCO -DIT -SSBS >>>>>>>>> BTYPE=--) >>>>>>>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98 >>>>>>>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98 >>>>>>>>> [ 3.603276] sp : ffff800083603990 >>>>>>>>> [ 3.677939] Call trace: >>>>>>>>> [ 3.680393] __virt_to_phys+0x68/0x98 >>>>>>>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 >>>>>>>>> [ 3.689214] >>>>>>>>> __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 >>>>>>>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 >>>>>>>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 >>>>>>>>> [ 3.705161] drm_client_register+0x60/0xb0 >>>>>>>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 >>>>>>>>> >>>>>>>>> So add a check 'is_vmalloc_addr'. >>>>>>>>> >>>>>>>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for >>>>>>>>> GEM DMA helpers") >>>>>>>>> Signed-off-by: Peng Fan <peng.fan@nxp.com> >>>>>>>> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> >>>>>>> I'm taking back my r-b. The memory is expected to by be physically >>>>>>> contiguous and vmalloc() won't guarantee that. >>>>>>> >>>>>> Agreed. >>>>> These smem_ fields are clearly designed for PCI BARs of >>>>> traditional graphics >>>>> cards. So can we even assume contiguous memory for DMA? That was my >>>>> assumption, but with IOMMUs it might not be the case. Fbdev-dma >>>>> only sets >>>>> smem_start to support a single old userspace driver. Maybe we >>>>> should further >>>>> restrict usage of this field by making it opt-in for each driver. Best >>>>> regards Thomas >>>> We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and >>>> remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is >>>> that with the old fb_mmap code we had to always fill out smem_start to >>>> make mmap work. But now that the various drm fbdev helpers have all >>>> their >>>> own mmap implementation, we could make this a lot cleaner. >>> Enabling CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM would still crash the NXP >>> driver. I think I'll add a flag to drm_fbdev_dma_setup() to set >>> smem_start from within lima, which is the only driver that requires >>> it.I'd like to remove CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM and all that, but >>> I fear that it would break someone's setup. Best regards Thomas > Yeah we'd always need to make this conditional on the memory not being in > the vmalloc range, or things will blow up. > >> I've been looking at >> >> https://lore.kernel.org/dri-devel/20240318-dark-mongoose-of-camouflage-7ac6ed@houat/ >> >> and I'm now confused to find that lima doesn't even set up fbdev support. > The mali driver here was the out-of-tree proprietary mali driver as the > consumer of such buffers. > > The "exporters" was just any random fbdev driver, and with the DRM option > to set the smem, also drm drivers could play in this role. It at least > seems to have helped a few people to move away from out-of-tree fbdev > drivers to upstream drm drivers (but still with the out-of-tree mali gpu > driver). Which means we've needed this for any display driver that > happens to have shipped together with one of these older mali gpus. > > It's a bit a mess, and it might indeed have outlived it's usefulness. Thanks a lot for explaining. Sounds like the kind of workaround that is almost impossible to remove. Let me send out a patch that connects the setting in fbdev-dma to the drm_leak_fbdev_smem parameter. At least fbdev-dma won't try to set smem_start unnecessarily. Best regards Thomas > > Cheers, Sima
diff --git a/drivers/gpu/drm/drm_fbdev_dma.c b/drivers/gpu/drm/drm_fbdev_dma.c index 6c9427bb4053..9e2eddb6eb5c 100644 --- a/drivers/gpu/drm/drm_fbdev_dma.c +++ b/drivers/gpu/drm/drm_fbdev_dma.c @@ -130,7 +130,12 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper, info->flags |= FBINFO_READS_FAST; /* signal caching */ info->screen_size = sizes->surface_height * fb->pitches[0]; info->screen_buffer = map.vaddr; - info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer)); + + if (is_vmalloc_addr(info->screen_buffer)) + info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer)); + else + info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer)); + info->fix.smem_len = info->screen_size; return 0;