@@ -72,6 +72,8 @@ static struct drm_driver drv_driver = {
.gem_prime_vmap = drm_gem_cma_prime_vmap,
.gem_prime_vunmap = drm_gem_cma_prime_vunmap,
.gem_prime_mmap = drm_gem_cma_prime_mmap,
+ .get_scanout_position = ltdc_crtc_scanoutpos,
+ .get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos,
};
static int drv_load(struct drm_device *ddev)
@@ -148,6 +148,8 @@
#define IER_TERRIE BIT(2) /* Transfer ERRor Interrupt Enable */
#define IER_RRIE BIT(3) /* Register Reload Interrupt enable */
+#define CPSR_CYPOS GENMASK(15, 0) /* Current Y position */
+
#define ISR_LIF BIT(0) /* Line Interrupt Flag */
#define ISR_FUIF BIT(1) /* Fifo Underrun Interrupt Flag */
#define ISR_TERRIF BIT(2) /* Transfer ERRor Interrupt Flag */
@@ -622,6 +624,49 @@ static void ltdc_crtc_disable_vblank(struct drm_crtc *crtc)
reg_clear(ldev->regs, LTDC_IER, IER_LIE);
}
+bool ltdc_crtc_scanoutpos(struct drm_device *ddev, unsigned int pipe,
+ bool in_vblank_irq, int *vpos, int *hpos,
+ ktime_t *stime, ktime_t *etime,
+ const struct drm_display_mode *mode)
+{
+ struct ltdc_device *ldev = ddev->dev_private;
+ int line, vactive_start, vactive_end, vtotal;
+
+ if (stime)
+ *stime = ktime_get();
+
+ /* The active area starts after vsync + front porch and ends
+ * at vsync + front porc + display size.
+ * The total height also include back porch.
+ * We have 3 possible cases to handle:
+ * - line < vactive_start: vpos = line - vactive_start and will be
+ * negative
+ * - vactive_start < line < vactive_end: vpos = line - vactive_start
+ * and will be positive
+ * - line > vactive_end: vpos = line - vtotal - vactive_start
+ * and will negative
+ *
+ * Computation for the two first cases are identical so we can
+ * simplify the code and only test if line > vactive_end
+ */
+ line = reg_read(ldev->regs, LTDC_CPSR) & CPSR_CYPOS;
+ vactive_start = reg_read(ldev->regs, LTDC_BPCR) & BPCR_AVBP;
+ vactive_end = reg_read(ldev->regs, LTDC_AWCR) & AWCR_AAH;
+ vtotal = reg_read(ldev->regs, LTDC_TWCR) & TWCR_TOTALH;
+
+ if (line > vactive_end)
+ *vpos = line - vtotal - vactive_start;
+ else
+ *vpos = line - vactive_start;
+
+ *hpos = 0;
+
+ if (etime)
+ *etime = ktime_get();
+
+ return true;
+}
+
static const struct drm_crtc_funcs ltdc_crtc_funcs = {
.destroy = drm_crtc_cleanup,
.set_config = drm_atomic_helper_set_config,
@@ -37,6 +37,11 @@ struct ltdc_device {
struct fps_info plane_fpsi[LTDC_MAX_LAYER];
};
+bool ltdc_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe,
+ bool in_vblank_irq, int *vpos, int *hpos,
+ ktime_t *stime, ktime_t *etime,
+ const struct drm_display_mode *mode);
+
int ltdc_load(struct drm_device *ddev);
void ltdc_unload(struct drm_device *ddev);
Hardware allow to read the position in scanout buffer so we can use this information to make wait of vblank more accurate. Active area bounds (start, end, total height) have already been computed and written in ltdc registers, read them and get the current line position to compute vpos value. Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com> --- drivers/gpu/drm/stm/drv.c | 2 ++ drivers/gpu/drm/stm/ltdc.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ drivers/gpu/drm/stm/ltdc.h | 5 +++++ 3 files changed, 52 insertions(+) -- 2.15.0