From: Dmitry Osipenko <dmitry.osipenko@collabora.com>
To: Robin Murphy <robin.murphy@arm.com>,
David Airlie <airlied@linux.ie>,
Gerd Hoffmann <kraxel@redhat.com>,
Gurchetan Singh <gurchetansingh@chromium.org>,
Chia-I Wu <olvaffe@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
Daniel Almeida <daniel.almeida@collabora.com>,
Gert Wollny <gert.wollny@collabora.com>,
Tomeu Vizoso <tomeu.vizoso@collabora.com>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
Rob Herring <robh@kernel.org>,
Steven Price <steven.price@arm.com>,
Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Gustavo Padovan <gustavo.padovan@collabora.com>,
dri-devel@lists.freedesktop.org,
Dmitry Osipenko <digetx@gmail.com>
Subject: Re: [PATCH v2 4/8] drm/virtio: Improve DMA API usage for shmem BOs
Date: Wed, 16 Mar 2022 16:52:12 +0300 [thread overview]
Message-ID: <13f77cd8-ed57-3593-ab21-dafce91ee85e@collabora.com> (raw)
In-Reply-To: <f2fed903-c61b-8040-ddfd-25a7bf0a625a@arm.com>
On 3/16/22 15:41, Robin Murphy wrote:
> On 2022-03-14 22:42, Dmitry Osipenko wrote:
>> DRM API requires the DRM's driver to be backed with the device that can
>> be used for generic DMA operations. The VirtIO-GPU device can't perform
>> DMA operations if it uses PCI transport because PCI device driver creates
>> a virtual VirtIO-GPU device that isn't associated with the PCI. Use PCI's
>> GPU device for the DRM's device instead of the VirtIO-GPU device and drop
>> DMA-related hacks from the VirtIO-GPU driver.
>>
>> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
>> ---
>> drivers/gpu/drm/virtio/virtgpu_drv.c | 22 +++++++---
>> drivers/gpu/drm/virtio/virtgpu_drv.h | 5 +--
>> drivers/gpu/drm/virtio/virtgpu_kms.c | 7 ++--
>> drivers/gpu/drm/virtio/virtgpu_object.c | 56 +++++--------------------
>> drivers/gpu/drm/virtio/virtgpu_vq.c | 13 +++---
>> 5 files changed, 37 insertions(+), 66 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c
>> b/drivers/gpu/drm/virtio/virtgpu_drv.c
>> index 5f25a8d15464..8449dad3e65c 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_drv.c
>> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
>> @@ -46,9 +46,9 @@ static int virtio_gpu_modeset = -1;
>> MODULE_PARM_DESC(modeset, "Disable/Enable modesetting");
>> module_param_named(modeset, virtio_gpu_modeset, int, 0400);
>> -static int virtio_gpu_pci_quirk(struct drm_device *dev, struct
>> virtio_device *vdev)
>> +static int virtio_gpu_pci_quirk(struct drm_device *dev)
>> {
>> - struct pci_dev *pdev = to_pci_dev(vdev->dev.parent);
>> + struct pci_dev *pdev = to_pci_dev(dev->dev);
>> const char *pname = dev_name(&pdev->dev);
>> bool vga = (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
>> char unique[20];
>> @@ -101,6 +101,7 @@ static int virtio_gpu_pci_quirk(struct drm_device
>> *dev, struct virtio_device *vd
>> static int virtio_gpu_probe(struct virtio_device *vdev)
>> {
>> struct drm_device *dev;
>> + struct device *dma_dev;
>> int ret;
>> if (drm_firmware_drivers_only() && virtio_gpu_modeset == -1)
>> @@ -109,18 +110,29 @@ static int virtio_gpu_probe(struct virtio_device
>> *vdev)
>> if (virtio_gpu_modeset == 0)
>> return -EINVAL;
>> - dev = drm_dev_alloc(&driver, &vdev->dev);
>> + /*
>> + * If GPU's parent is a PCI device, then we will use this PCI device
>> + * for the DRM's driver device because GPU won't have PCI's IOMMU
>> DMA
>> + * ops in this case since GPU device is sitting on a separate
>> (from PCI)
>> + * virtio-bus.
>> + */
>> + if (!strcmp(vdev->dev.parent->bus->name, "pci"))
>
> Nit: dev_is_pci() ?
Yes, thank you.
> However, what about other VirtIO transports? Wouldn't virtio-mmio with
> F_ACCESS_PLATFORM be in a similar situation?
I couldn't find anyone using virtio-mmio for the GPU, both Qemu and
crosvm support only PCI transport for GPU.
But I'm now looking at virtio_mmio_probe() and see that virtio-mmio
devices actually should be in the exactly same position as PCI devices.
So you should be right and we need to use vdev->dev.parent for the DRM
device universally. I'll improve it in the v3, thank you again.
next prev parent reply other threads:[~2022-03-16 13:52 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-14 22:42 [PATCH v2 0/8] Add memory shrinker to VirtIO-GPU DRM driver Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 1/8] drm/virtio: Correct drm_gem_shmem_get_sg_table() error handling Dmitry Osipenko
2022-03-15 13:05 ` Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 2/8] drm/virtio: Check whether transferred 2D BO is shmem Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 3/8] drm/virtio: Unlock GEM reservations in error code path Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 4/8] drm/virtio: Improve DMA API usage for shmem BOs Dmitry Osipenko
2022-03-16 12:41 ` Robin Murphy
2022-03-16 13:52 ` Dmitry Osipenko [this message]
2022-03-17 1:09 ` Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 5/8] drm/shmem-helper: Correct doc-comment of drm_gem_shmem_get_sg_table() Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 6/8] drm/shmem-helper: Add generic memory shrinker Dmitry Osipenko
2022-03-16 15:04 ` Steven Price
2022-03-16 23:03 ` Dmitry Osipenko
2022-03-16 20:00 ` Rob Clark
2022-03-17 0:13 ` Dmitry Osipenko
2022-03-17 16:13 ` Rob Clark
2022-03-17 17:43 ` Dmitry Osipenko
2022-03-17 17:32 ` Daniel Vetter
2022-03-17 17:45 ` Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 7/8] drm/virtio: Support memory shrinking Dmitry Osipenko
2022-03-15 12:43 ` Emil Velikov
2022-03-16 14:23 ` Dmitry Osipenko
2022-03-14 22:42 ` [PATCH v2 8/8] drm/panfrost: Switch to generic memory shrinker Dmitry Osipenko
2022-03-14 23:26 ` Alyssa Rosenzweig
2022-03-14 23:32 ` Dmitry Osipenko
2022-03-16 15:04 ` Steven Price
2022-03-16 23:04 ` Dmitry Osipenko
2022-03-18 14:41 ` Dmitry Osipenko
2022-03-18 14:47 ` Steven Price
2022-03-18 17:09 ` Dmitry Osipenko
2022-03-15 12:47 ` [PATCH v2 0/8] Add memory shrinker to VirtIO-GPU DRM driver Emil Velikov
2022-03-15 13:10 ` Dmitry Osipenko
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