On Mon, 18 Mar 2024 15:11:42 +0000
Robin Murphy <robin.murphy@xxxxxxx> wrote:
> On 18/03/2024 2:51 pm, Steven Price wrote:
> > virt_to_pfn() isn't available on x86 (except to xen) so breaks
> > COMPILE_TEST builds. Avoid its use completely by instead storing the
> > struct page pointer allocated in panthor_device_init() and using
> > page_to_pfn() instead.
> >
> > Signed-off-by: Steven Price <steven.price@xxxxxxx>
> > ---
> > drivers/gpu/drm/panthor/panthor_device.c | 10 ++++++----
> > drivers/gpu/drm/panthor/panthor_device.h | 2 +-
> > 2 files changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> > index 69deb8e17778..3c30da03fa48 100644
> > --- a/drivers/gpu/drm/panthor/panthor_device.c
> > +++ b/drivers/gpu/drm/panthor/panthor_device.c
> > @@ -154,6 +154,7 @@ int panthor_device_init(struct panthor_device *ptdev)
> > {
> > struct resource *res;
> > struct page *p;
> > + u32 *dummy_page_virt;
> > int ret;
> >
> > ptdev->coherent = device_get_dma_attr(ptdev->base.dev) == DEV_DMA_COHERENT;
> > @@ -172,9 +173,10 @@ int panthor_device_init(struct panthor_device *ptdev)
> > if (!p)
> > return -ENOMEM;
> >
> > - ptdev->pm.dummy_latest_flush = page_address(p);
> > + ptdev->pm.dummy_latest_flush = p;
> > + dummy_page_virt = page_address(p);
> > ret = drmm_add_action_or_reset(&ptdev->base, panthor_device_free_page,
> > - ptdev->pm.dummy_latest_flush);
> > + dummy_page_virt);
>
> Nit: I was about to say I'd be inclined to switch the callback to
> __free_page() instead, but then I realise there's no real need to be
> reinventing that in the first place:
>
> dummy_page_virt = (void *)devm_get_free_pages(ptdev->base.dev,
> GFP_KERNEL | GFP_ZERO, 0);
IIRC, the drm_device object might outlive the device it's been created
from if a process holds on the DRM dev FD after an unplug happened,
which can happen if panthor_device_unplug() is called from the reset
path (when a reset fails).
> if (!dummy_page_virt)
> return -ENOMEM;
>
> ptdev->pm.dummy_latest_flush = virt_to_page(dummy_page_virt);
>
> Cheers,
> Robin.
>
> > if (ret)
> > return ret;
> >
> > @@ -184,7 +186,7 @@ int panthor_device_init(struct panthor_device *ptdev)
> > * happens while the dummy page is mapped. Zero cannot be used because
> > * that means 'always flush'.
> > */
> > - *ptdev->pm.dummy_latest_flush = 1;
> > + *dummy_page_virt = 1;
> >
> > INIT_WORK(&ptdev->reset.work, panthor_device_reset_work);
> > ptdev->reset.wq = alloc_ordered_workqueue("panthor-reset-wq", 0);
> > @@ -353,7 +355,7 @@ static vm_fault_t panthor_mmio_vm_fault(struct vm_fault *vmf)
> > if (active)
> > pfn = __phys_to_pfn(ptdev->phys_addr + CSF_GPU_LATEST_FLUSH_ID);
> > else
> > - pfn = virt_to_pfn(ptdev->pm.dummy_latest_flush);
> > + pfn = page_to_pfn(ptdev->pm.dummy_latest_flush);
> > break;
> >
> > default:
> > diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> > index 51c9d61b6796..c84c27dcc92c 100644
> > --- a/drivers/gpu/drm/panthor/panthor_device.h
> > +++ b/drivers/gpu/drm/panthor/panthor_device.h
> > @@ -160,7 +160,7 @@ struct panthor_device {
> > * Used to replace the real LATEST_FLUSH page when the GPU
> > * is suspended.
> > */
> > - u32 *dummy_latest_flush;
> > + struct page *dummy_latest_flush;
> > } pm;
> > };
> >
