[RFC PATCH 09/16] drm/rockchip: ebc: Implement global refreshes

Samuel Holland
2022-04-13T22:20:18Z

The global refresh mode is used to initialize and clear the screen.
It is the most efficient refresh mode. It uses two pixel buffers (old
and new) and a frame count. The frame count is set to the number of
phases in the waveform. The hardware then looks up the combination of
(old pixel value, new pixel value, frame number) in the LUT and sends
the resulting polarity value to the display.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---

drivers/gpu/drm/rockchip/rockchip_ebc.c | 48 ++++++++++++++++++++++++-
1 file changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_ebc.c b/drivers/gpu/drm/rockchip/rockchip_ebc.c
index ca3173b28d1c..cb6dc567e94c 100644
--- a/drivers/gpu/drm/rockchip/rockchip_ebc.c
+++ b/drivers/gpu/drm/rockchip/rockchip_ebc.c
@@ -127,6 +127,7 @@
#define EBC_NUM_LUT_REGS 0x1000
#define EBC_NUM_SUPPLIES 3

+#define EBC_REFRESH_TIMEOUT msecs_to_jiffies(3000)
#define EBC_SUSPEND_DELAY_MS 2000

struct rockchip_ebc {
@@ -269,8 +270,23 @@ static void rockchip_ebc_global_refresh(struct rockchip_ebc *ebc,
{
struct drm_device *drm = &ebc->drm;
u32 gray4_size = ctx->gray4_size;
+ struct device *dev = drm->dev;

- drm_dbg(drm, "global refresh\n");
+ dma_sync_single_for_device(dev, virt_to_phys(ctx->next),
+ gray4_size, DMA_TO_DEVICE);
+ dma_sync_single_for_device(dev, virt_to_phys(ctx->prev),
+ gray4_size, DMA_TO_DEVICE);
+
+ reinit_completion(&ebc->display_end);
+ regmap_write(ebc->regmap, EBC_CONFIG_DONE,
+ EBC_CONFIG_DONE_REG_CONFIG_DONE);
+ regmap_write(ebc->regmap, EBC_DSP_START,
+ ebc->dsp_start |
+ EBC_DSP_START_DSP_FRM_TOTAL(ebc->lut.num_phases - 1) |
+ EBC_DSP_START_DSP_FRM_START);
+ if (!wait_for_completion_timeout(&ebc->display_end,
+ EBC_REFRESH_TIMEOUT))
+ drm_err(drm, "Refresh timed out!\n");

memcpy(ctx->prev, ctx->next, gray4_size);
}
@@ -289,6 +305,7 @@ static void rockchip_ebc_refresh(struct rockchip_ebc *ebc,
enum drm_epd_waveform waveform)
{
struct drm_device *drm = &ebc->drm;
+ u32 dsp_ctrl = 0, epd_ctrl = 0;
struct device *dev = drm->dev;
int ret, temperature;

@@ -334,11 +351,40 @@ static void rockchip_ebc_refresh(struct rockchip_ebc *ebc,
ebc->lut.buf, EBC_NUM_LUT_REGS);
}

+ regmap_write(ebc->regmap, EBC_DSP_START,
+ ebc->dsp_start);
+
+ /*
+ * The hardware has a separate bit for each mode, with some priority
+ * scheme between them. For clarity, only set one bit at a time.
+ */
+ if (global_refresh) {
+ dsp_ctrl |= EBC_DSP_CTRL_DSP_LUT_MODE;
+ } else {
+ epd_ctrl |= EBC_EPD_CTRL_DSP_THREE_WIN_MODE;
+ }
+ regmap_update_bits(ebc->regmap, EBC_EPD_CTRL,
+ EBC_EPD_CTRL_DSP_THREE_WIN_MODE,
+ epd_ctrl);
+ regmap_update_bits(ebc->regmap, EBC_DSP_CTRL,
+ EBC_DSP_CTRL_DSP_LUT_MODE,
+ dsp_ctrl);
+
+ regmap_write(ebc->regmap, EBC_WIN_MST0,
+ virt_to_phys(ctx->next));
+ regmap_write(ebc->regmap, EBC_WIN_MST1,
+ virt_to_phys(ctx->prev));
+
if (global_refresh)
rockchip_ebc_global_refresh(ebc, ctx);
else
rockchip_ebc_partial_refresh(ebc, ctx);

+ /* Drive the output pins low once the refresh is complete. */
+ regmap_write(ebc->regmap, EBC_DSP_START,
+ ebc->dsp_start |
+ EBC_DSP_START_DSP_OUT_LOW);
+
pm_runtime_mark_last_busy(dev);
pm_runtime_put_autosuspend(dev);
}
--
2.35.1