On Fri, Sep 13, 2013 at 07:05:31PM +0530, Sandeep Ramankutty wrote:
> Change: Add support to change the pixel format, base surface address, tiling mode, tiling
> offset on the flow during the primary plane flip.
Tell us why first. Why this patch is necesary is the fundamental reason
that we need to record in the changelog. Discuss the background and the
motivation that leads us to require a kernel patch.
> Issue: This support is needed by hardware composer to meet the performance
> optimization requirement for 3D benchmark. This patch enables change in
> pixel format and tiling params without adding and removing the framebuffer.
> Adding and removing the framebuffer impacts performance.
So you say. Examples are vital, especially if you make a claim as
towards performance. And then to back those up with tests to make sure
nothing is broken. The other question is how do we end up regularly
flipping between pixel formats that it shows up in a performance
benchmark.
> Change Details-
> drm: Defined function pointer set_pixelformat in drm_crtc_funcs. drm_crtc.c is modified
> to execute the function to update pixel format.
> drm/i915: intel_crtc_set_pixel_format() implemented in i915 driver code (intel_display.c)
> and set to drm_crtc_funcs->set_pixelformat.
> haswell_set_pixelformat() implemented to update pixel format. This is specific to Haswell
> haswell_update_plane() implemented to update changes in tiling offset, surface
> base address and stride-fb->pitches[0]. Sends MI command to update the params
> in primary plane control registers.
You don't need to repeat the patch, just tell us what complications you
encountered and how you resolved them, or what issues remain.
>
> Change-Id: I4b0af83f641b2b79ee4f5c3401790d7d90ccd9ef
> Signed-off-by: Pallavi G <pallavi.g@xxxxxxxxx>
> Signed-off-by: Sandeep Ramakutty <sandeepx.ramakutty@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_crtc.c | 15 +++-
> drivers/gpu/drm/i915/intel_display.c | 156 ++++++++++++++++++++++++++++++++++
> include/drm/drm_crtc.h | 8 ++
> 3 files changed, 176 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index c9f9f3d..4739b6c 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -3518,9 +3518,18 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
> }
>
> if (crtc->fb->pixel_format != fb->pixel_format) {
> - DRM_DEBUG_KMS("Page flip is not allowed to change frame buffer format.\n");
> - ret = -EINVAL;
> - goto out;
> + if (crtc->funcs->set_pixelformat == NULL) {
> + DRM_DEBUG_KMS("Pixel format change not allowed");
> + ret = -EINVAL;
> + goto out;
> + }
> + /* supports dynamic change in pixel format */
> + ret = crtc->funcs->set_pixelformat(crtc, fb->pixel_format);
Bleh.
Just install a default set_pixelformat that returns -EINVAL and lose the
i++; /* increment i after reading */
Also the current use of crtc->funcs->set_pixelformat suggests confusion
is paramount.
> + if (ret) {
> + DRM_DEBUG_KMS("Pixel format change failed %d",
> + fb->pixel_format);
> + goto out;
> + }
What happens if the flip fails afterwards? Where's the unwind? Where's
the protection that prevents the format change whilst the current
scanout is still visible? Perhaps this being the ring emission is being
attempted far too early.
> }
>
> if (page_flip->flags & DRM_MODE_PAGE_FLIP_EVENT) {
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 955df91..7bfe088 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -45,6 +45,7 @@ bool intel_pipe_has_type(struct drm_crtc *crtc, int type);
> static void intel_increase_pllclock(struct drm_crtc *crtc);
> static void intel_crtc_update_cursor(struct drm_crtc *crtc, bool on);
>
> +
> typedef struct {
> int min, max;
> } intel_range_t;
> @@ -1959,6 +1960,128 @@ static int i9xx_update_plane(struct drm_crtc *crtc, struct drm_framebuffer *fb,
> return 0;
> }
>
> +/* Set Pixel format for Haswell using MI commands */
> +static int haswell_set_pixelformat(struct drm_crtc *crtc, u32 pixel_format)
> +{
> + u32 dspcntr, reg;
> + struct drm_device *dev = crtc->dev;
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> + struct intel_ring_buffer *ring = &dev_priv->ring[BCS];
> + int ret = 0;
Interesting choice of ring.
> + reg = DSPCNTR(intel_crtc->pipe);
> + dspcntr = I915_READ(reg);
> + DRM_DEBUG_DRIVER("pixel format = %d\n", pixel_format);
> + /* Mask out pixel format bits in case we change it */
> + dspcntr &= ~DISPPLANE_PIXFORMAT_MASK;
> + switch (pixel_format) {
> + case DRM_FORMAT_C8:
> + dspcntr |= DISPPLANE_8BPP;
> + break;
> + case DRM_FORMAT_XRGB1555:
> + case DRM_FORMAT_ARGB1555:
> + dspcntr |= DISPPLANE_BGRX555;
> + break;
> + case DRM_FORMAT_RGB565:
> + dspcntr |= DISPPLANE_BGRX565;
> + break;
> + case DRM_FORMAT_XRGB8888:
> + case DRM_FORMAT_ARGB8888:
> + dspcntr |= DISPPLANE_BGRX888;
> + break;
> + case DRM_FORMAT_XBGR8888:
> + case DRM_FORMAT_ABGR8888:
> + dspcntr |= DISPPLANE_RGBX888;
> + break;
> + case DRM_FORMAT_XRGB2101010:
> + case DRM_FORMAT_ARGB2101010:
> + dspcntr |= DISPPLANE_BGRX101010;
> + break;
> + case DRM_FORMAT_XBGR2101010:
> + case DRM_FORMAT_ABGR2101010:
> + dspcntr |= DISPPLANE_RGBX101010;
> + break;
> + default:
> + DRM_ERROR("Unsupported pixel format 0x%08x\n", pixel_format);
> + return -EINVAL;
> + }
> +
> + /* Write pixel format update command to ring */
> + ret = intel_ring_begin(ring, 4);
> + if (ret) {
> + DRM_ERROR("MI Command emit failed.\n");
> + return ret;
> + }
> + intel_ring_emit(ring, MI_NOOP);
> + intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
> + intel_ring_emit(ring, reg);
> + intel_ring_emit(ring, dspcntr);
> + intel_ring_advance(ring);
> + return 0;
> +}
> +
> +/* Update the primary plane registers. Uses MI commands */
> +static int haswell_update_plane(struct drm_crtc *crtc,
> + struct drm_framebuffer *fb, int x, int y)
> +{
> + int ret;
> + struct drm_device *dev = crtc->dev;
> + struct drm_i915_private *dev_priv = dev->dev_private;
> + struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> + struct intel_ring_buffer *ring = &dev_priv->ring[BCS];
> + struct drm_i915_gem_object *obj;
> + int plane = intel_crtc->plane;
> +
> + switch (plane) {
> + case 0:
> + case 1:
> + case 2:
> + break;
> + default:
> + DRM_ERROR("Can't update plane %c\n", plane_name(plane));
> + return -EINVAL;
> + }
> + obj = to_intel_framebuffer(fb)->obj;
> +
> + /* Set pixel format */
> + haswell_set_pixelformat(crtc, fb->pixel_format);
> +
> + /* Set tiling offsets. Tiling mode is not set here as *
> + * it is set from intel_gen7_queue_flip. Send MI Command *
> + * to change - *
> + * 1. Tiling offset *
> + * 2. stride - fb->pitches[0] *
> + * 2. surface base address *
> + * Linear offset and tile offset is same for Haswell */
The first rule of adding code is to be consistent with the surrounding
code.
> + intel_crtc->dspaddr_offset =
> + intel_gen4_compute_page_offset(&x, &y, obj->tiling_mode,
> + fb->bits_per_pixel / 8,
> + fb->pitches[0]);
> +
> + DRM_DEBUG_KMS("Writing base %08X %08lX %d %d %d\n",
> + obj->gtt_offset, intel_crtc->dspaddr_offset,
> + x, y, fb->pitches[0]);
> +
> + /* Emit MI commands here */
> + ret = intel_ring_begin(ring, 10);
> + if (ret)
> + return ret;
> + intel_ring_emit(ring, MI_NOOP);
> + intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
> + intel_ring_emit(ring, DSPOFFSET(plane));
> + intel_ring_emit(ring, (y << 16) | x);
> + intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
> + intel_ring_emit(ring, DSPSTRIDE(plane));
> + intel_ring_emit(ring, fb->pitches[0]);
> + intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
> + intel_ring_emit(ring, DSPSURF(plane));
> + intel_ring_emit(ring, obj->gtt_offset + intel_crtc->dspaddr_offset);
> + intel_ring_advance(ring);
> +
> + return 0;
> +}
> +
> static int ironlake_update_plane(struct drm_crtc *crtc,
> struct drm_framebuffer *fb, int x, int y)
> {
> @@ -7494,9 +7617,26 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
> struct drm_framebuffer *old_fb = crtc->fb;
> struct drm_i915_gem_object *obj = to_intel_framebuffer(fb)->obj;
> struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> + struct intel_framebuffer *intel_fb;
> struct intel_unpin_work *work;
> unsigned long flags;
> int ret;
> + /*
> + * TILEOFF registers can't be changed via MI display flips.
> + * Changes in pitches[0] and offsets[0] updates the primary plane
> + * control registers.
> + */
> + intel_fb = to_intel_framebuffer(crtc->fb);
> + if ((IS_HASWELL(dev)) &&
> + ((obj->tiling_mode != intel_fb->obj->tiling_mode) ||
> + (fb->offsets[0] != crtc->fb->offsets[0]) ||
> + (fb->pitches[0] != crtc->fb->pitches[0]))) {
> + DRM_DEBUG_DRIVER(" crtc fb: pitch = %d offset = %d\n",
> + crtc->fb->pitches[0], crtc->fb->offsets[0]);
> + DRM_DEBUG_DRIVER(" input fb: pitch = %d offset = %d\n",
> + fb->pitches[0], fb->offsets[0]);
> + haswell_update_plane(crtc, fb, 0, 0);
We do expect code to at least bear some resemblence to the CODING_STYLE.
Also this techinique does not look to be haswell specific, and with some
rearrangement could be written much more neatly.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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