[PATCH V5 2/2] drm/vkms: Add support for virtual hardware mode
Melissa Wen
mwen at igalia.com
Tue Aug 3 19:35:11 UTC 2021
On 08/01, Sumera Priyadarsini wrote:
> Add a virtual hardware or vblank-less mode as a module
> to enable VKMS to emulate virtual hardware drivers. This means
> no vertical blanking events occur and pageflips are completed
> arbitrarily and when required for updating the frame.
>
> Add a new drm_crtc_helper_funcs struct,
> vkms_virtual_crtc_helper_funcs() which holds the atomic helpers
> for virtual hardware mode. Rename the existing
> vkms_crtc_helper_funcs struct to vkms_vblank_crtc_helper_funcs
> which holds atomic helpers for the vblank mode.
> This makes the code flow clearer and testing
> virtual hardware mode.
>
Hi Sumera,
Thanks for working to enable it.
> Add a function vkms_crtc_composer() which calls the helper function,
> vkms_composer_common() for plane composition in vblank-less mode.
> vkms_crtc_composer() is directly called in the atomic hook in
> vkms_crtc_atomic_begin().
>
> However, some crc captures still use vblanks which causes the crc-based
> igt tests to crash. Currently, I am unsure about how to approach the
> one-shot implementation of crc reads so I am still working on that.
>
We've briefly discussed on irc that we could go ahead without covering
crc-based tests. However, we should not introduce errors in the driver
when trying to set crc source.
For this, we need to avoid that vblank_get/put calls in
vkms_set_crc_source (vkms_composer.c) Can you check it, please?
> This patchset has been tested with the igt tests- kms_writeback, kms_atomic
> , kms_lease, kms_flip, kms_pipe_get_crc and preserves results except for
> subtests related to crc reads and skips tests that rely on vertical
> blanking.
>
> The patch is based on Rodrigo Siqueira's
> patch(https://patchwork.freedesktop.org/patch/316851/?series=48469&rev=3)
> and the ensuing review.
>
> Signed-off-by: Sumera Priyadarsini <sylphrenadin at gmail.com>
> ---
> Changes in V5:
> - Move vkms_crtc_composer() to this patch(Melissa)
> - Add more clarification for "vblank-less" mode(Pekka)
> - Replace kzalloc() with kvmalloc() in compose_active_planes()
> to fix memory allocation error for output frame
> - Fix checkpatch warnings (Melissa)
> Changes in V3:
> - Refactor patchset(Melissa)
> Changes in V2:
> - Add atomic helper functions in a separate struct for virtual hardware
> mode (Daniel)
> - Remove spinlock across 'vkms_output->lock' in vkms_crtc.c(Daniel)
> - Add vkms_composer_common() (Daniel)
> ---
> drivers/gpu/drm/vkms/vkms_composer.c | 21 ++++++++++--
> drivers/gpu/drm/vkms/vkms_crtc.c | 51 ++++++++++++++++++++--------
> drivers/gpu/drm/vkms/vkms_drv.c | 16 ++++++---
> drivers/gpu/drm/vkms/vkms_drv.h | 2 ++
> 4 files changed, 69 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index bf3d576db225..2988d5b49eb6 100644
> --- a/drivers/gpu/drm/vkms/vkms_composer.c
> +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> @@ -176,11 +176,12 @@ static int compose_active_planes(void **vaddr_out,
> {
> struct drm_framebuffer *fb = &primary_composer->fb;
> struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
> +
> const void *vaddr;
> int i;
>
> if (!*vaddr_out) {
> - *vaddr_out = kzalloc(gem_obj->size, GFP_KERNEL);
> + *vaddr_out = kvmalloc(gem_obj->size, GFP_KERNEL);
Is this change necessary to enable vblank-less mode? Or is it treating
another problem?
> if (!*vaddr_out) {
> DRM_ERROR("Cannot allocate memory for output frame.");
> return -ENOMEM;
> @@ -229,7 +230,7 @@ int vkms_composer_common(struct vkms_crtc_state *crtc_state,
>
> if (ret) {
> if ((ret == -EINVAL || ret == -ENOMEM) && !wb_pending)
> - kfree(vaddr_out);
> + kvfree(vaddr_out);
> return ret;
> }
>
> @@ -241,7 +242,7 @@ int vkms_composer_common(struct vkms_crtc_state *crtc_state,
> crtc_state->wb_pending = false;
> spin_unlock_irq(&out->composer_lock);
> } else {
> - kfree(vaddr_out);
> + kvfree(vaddr_out);
> }
>
> return 0;
> @@ -295,6 +296,20 @@ void vkms_composer_worker(struct work_struct *work)
> drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
> }
>
> +void vkms_crtc_composer(struct vkms_crtc_state *crtc_state)
> +{
> + struct drm_crtc *crtc = crtc_state->base.crtc;
> + struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
> + u32 crc32 = 0;
> + int ret;
> +
> + ret = vkms_composer_common(crtc_state, out, crtc_state->wb_pending, &crc32);
> + if (ret == -EINVAL)
> + return;
> +
> + drm_crtc_add_crc_entry(crtc, true, 0, &crc32);
> +}
> +
> static const char * const pipe_crc_sources[] = {"auto"};
>
> const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 57bbd32e9beb..8477b33c4d09 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -222,20 +222,20 @@ static int vkms_crtc_atomic_check(struct drm_crtc *crtc,
> return 0;
> }
>
> -static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,
> - struct drm_atomic_state *state)
> +static void vkms_vblank_crtc_atomic_enable(struct drm_crtc *crtc,
> + struct drm_atomic_state *state)
> {
> drm_crtc_vblank_on(crtc);
> }
>
> -static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
> - struct drm_atomic_state *state)
> +static void vkms_vblank_crtc_atomic_disable(struct drm_crtc *crtc,
> + struct drm_atomic_state *state)
> {
> drm_crtc_vblank_off(crtc);
> }
>
> -static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,
> - struct drm_atomic_state *state)
> +static void vkms_vblank_crtc_atomic_begin(struct drm_crtc *crtc,
> + struct drm_atomic_state *state)
> {
> struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
>
> @@ -245,8 +245,8 @@ static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,
> spin_lock_irq(&vkms_output->lock);
> }
>
> -static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
> - struct drm_atomic_state *state)
> +static void vkms_vblank_crtc_atomic_flush(struct drm_crtc *crtc,
> + struct drm_atomic_state *state)
> {
> struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
>
> @@ -268,18 +268,38 @@ static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
> spin_unlock_irq(&vkms_output->lock);
> }
>
> -static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
> +/*
> + * Crtc functions for virtual hardware/vblankless mode
> + */
> +static void vkms_virtual_crtc_atomic_flush(struct drm_crtc *crtc,
> + struct drm_atomic_state *state)
> +{
> + struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
> + struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(crtc->state);
> +
> + vkms_crtc_composer(vkms_state);
> +
> + vkms_output->composer_state = to_vkms_crtc_state(crtc->state);
> +}
> +
> +static const struct drm_crtc_helper_funcs vkms_vblank_crtc_helper_funcs = {
> .atomic_check = vkms_crtc_atomic_check,
> - .atomic_begin = vkms_crtc_atomic_begin,
> - .atomic_flush = vkms_crtc_atomic_flush,
> - .atomic_enable = vkms_crtc_atomic_enable,
> - .atomic_disable = vkms_crtc_atomic_disable,
> + .atomic_begin = vkms_vblank_crtc_atomic_begin,
> + .atomic_flush = vkms_vblank_crtc_atomic_flush,
> + .atomic_enable = vkms_vblank_crtc_atomic_enable,
> + .atomic_disable = vkms_vblank_crtc_atomic_disable,
> +};
> +
> +static const struct drm_crtc_helper_funcs vkms_virtual_crtc_helper_funcs = {
> + .atomic_check = vkms_crtc_atomic_check,
> + .atomic_flush = vkms_virtual_crtc_atomic_flush,
> };
>
> int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
> struct drm_plane *primary, struct drm_plane *cursor)
> {
> struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
> + struct vkms_device *vkmsdev = drm_device_to_vkms_device(dev);
> int ret;
>
> ret = drm_crtc_init_with_planes(dev, crtc, primary, cursor,
> @@ -289,7 +309,10 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
> return ret;
> }
>
> - drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs);
> + if (vkmsdev->config->virtual_hw)
> + drm_crtc_helper_add(crtc, &vkms_virtual_crtc_helper_funcs);
> + else
> + drm_crtc_helper_add(crtc, &vkms_vblank_crtc_helper_funcs);
>
> spin_lock_init(&vkms_out->lock);
> spin_lock_init(&vkms_out->composer_lock);
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index 0ffe5f0e33f7..ee78f5eef653 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -51,6 +51,10 @@ static bool enable_overlay;
> module_param_named(enable_overlay, enable_overlay, bool, 0444);
> MODULE_PARM_DESC(enable_overlay, "Enable/Disable overlay support");
>
> +static bool enable_virtual_hw;
> +module_param_named(enable_virtual_hw, enable_virtual_hw, bool, 0444);
> +MODULE_PARM_DESC(enable_virtual_hw, "Enable/Disable virtual hardware mode(vblank-less mode)");
> +
> DEFINE_DRM_GEM_FOPS(vkms_driver_fops);
>
> static void vkms_release(struct drm_device *dev)
> @@ -98,6 +102,7 @@ static int vkms_config_show(struct seq_file *m, void *data)
> seq_printf(m, "writeback=%d\n", vkmsdev->config->writeback);
> seq_printf(m, "cursor=%d\n", vkmsdev->config->cursor);
> seq_printf(m, "overlay=%d\n", vkmsdev->config->overlay);
> + seq_printf(m, "virtual_hw=%d\n", vkmsdev->config->virtual_hw);
>
> return 0;
> }
> @@ -191,10 +196,12 @@ static int vkms_create(struct vkms_config *config)
> goto out_devres;
> }
>
> - ret = drm_vblank_init(&vkms_device->drm, 1);
> - if (ret) {
> - DRM_ERROR("Failed to vblank\n");
> - goto out_devres;
> + if (!vkms_device->config->virtual_hw) {
> + ret = drm_vblank_init(&vkms_device->drm, 1);
> + if (ret) {
> + DRM_ERROR("Failed to vblank\n");
> + goto out_devres;
> + }
> }
>
> ret = vkms_modeset_init(vkms_device);
> @@ -229,6 +236,7 @@ static int __init vkms_init(void)
> config->cursor = enable_cursor;
> config->writeback = enable_writeback;
> config->overlay = enable_overlay;
> + config->virtual_hw = enable_virtual_hw;
>
> return vkms_create(config);
> }
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index 01beba424f18..770594e07f0e 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -92,6 +92,7 @@ struct vkms_config {
> bool writeback;
> bool cursor;
> bool overlay;
> + bool virtual_hw;
> /* only set when instantiated */
> struct vkms_device *dev;
> };
> @@ -136,6 +137,7 @@ int vkms_composer_common(struct vkms_crtc_state *crtc_state, struct vkms_output
> bool wb_pending, uint32_t *crcs);
> void vkms_composer_worker(struct work_struct *work);
> void vkms_set_composer(struct vkms_output *out, bool enabled);
> +void vkms_crtc_composer(struct vkms_crtc_state *crtc_state);
>
> /* Writeback */
> int vkms_enable_writeback_connector(struct vkms_device *vkmsdev);
> --
> 2.31.1
>
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