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Subject[PATCH v5 1/2] drm: tilcdc: implement palette loading for rev1
Date
Revision 1 of the IP doesn't work if we don't load the palette (even
if it's not used, which is the case for the RGB565 format).

Add a function called from tilcdc_crtc_enable() which performs all
required actions if we're dealing with a rev1 chip.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 88 +++++++++++++++++++++++++++++++++++-
1 file changed, 87 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index db2f538..937697d 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -21,11 +21,15 @@
#include <drm/drm_flip_work.h>
#include <drm/drm_plane_helper.h>
#include <linux/workqueue.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>

#include "tilcdc_drv.h"
#include "tilcdc_regs.h"

-#define TILCDC_VBLANK_SAFETY_THRESHOLD_US 1000
+#define TILCDC_VBLANK_SAFETY_THRESHOLD_US 1000
+#define TILCDC_REV1_PALETTE_SIZE 32
+#define TILCDC_REV1_PALETTE_FIRST_ENTRY 0x4000

struct tilcdc_crtc {
struct drm_crtc base;
@@ -53,6 +57,10 @@ struct tilcdc_crtc {

int sync_lost_count;
bool frame_intact;
+
+ dma_addr_t palette_dma_handle;
+ void *palette_base;
+ struct completion palette_loaded;
};
#define to_tilcdc_crtc(x) container_of(x, struct tilcdc_crtc, base)

@@ -98,6 +106,55 @@ static void set_scanout(struct drm_crtc *crtc, struct drm_framebuffer *fb)
tilcdc_crtc->curr_fb = fb;
}

+/*
+ * The driver currently only supports the RGB565 format for revision 1. For
+ * 16 bits-per-pixel the palette block is bypassed, but the first 32 bytes of
+ * the framebuffer are still considered palette. The first 16-bit entry must
+ * be 0x4000 while all other entries must be zeroed.
+ */
+static void tilcdc_crtc_load_palette(struct drm_crtc *crtc)
+{
+ u32 dma_fb_base, dma_fb_ceiling, raster_ctl;
+ struct tilcdc_crtc *tilcdc_crtc;
+ struct drm_device *dev;
+ u16 *first_entry;
+
+ dev = crtc->dev;
+ tilcdc_crtc = to_tilcdc_crtc(crtc);
+ first_entry = tilcdc_crtc->palette_base;
+
+ *first_entry = TILCDC_REV1_PALETTE_FIRST_ENTRY;
+
+ dma_fb_base = tilcdc_read(dev, LCDC_DMA_FB_BASE_ADDR_0_REG);
+ dma_fb_ceiling = tilcdc_read(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG);
+ raster_ctl = tilcdc_read(dev, LCDC_RASTER_CTRL_REG);
+
+ /* Tell the LCDC where the palette is located. */
+ tilcdc_write(dev, LCDC_DMA_FB_BASE_ADDR_0_REG,
+ tilcdc_crtc->palette_dma_handle);
+ tilcdc_write(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG,
+ (u32)tilcdc_crtc->palette_dma_handle
+ + TILCDC_REV1_PALETTE_SIZE - 1);
+
+ /* Load it. */
+ tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
+ LCDC_PALETTE_LOAD_MODE(DATA_ONLY));
+ tilcdc_set(dev, LCDC_RASTER_CTRL_REG,
+ LCDC_PALETTE_LOAD_MODE(PALETTE_ONLY));
+
+ /* Enable the LCDC and wait for palette to be loaded. */
+ tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_V1_PL_INT_ENA);
+ tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
+
+ wait_for_completion(&tilcdc_crtc->palette_loaded);
+
+ /* Restore the registers. */
+ tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
+ tilcdc_write(dev, LCDC_DMA_FB_BASE_ADDR_0_REG, dma_fb_base);
+ tilcdc_write(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG, dma_fb_ceiling);
+ tilcdc_write(dev, LCDC_RASTER_CTRL_REG, raster_ctl);
+}
+
static void tilcdc_crtc_enable_irqs(struct drm_device *dev)
{
struct tilcdc_drm_private *priv = dev->dev_private;
@@ -152,6 +209,7 @@ static void tilcdc_crtc_enable(struct drm_crtc *crtc)
{
struct drm_device *dev = crtc->dev;
struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
+ struct tilcdc_drm_private *priv = dev->dev_private;

WARN_ON(!drm_modeset_is_locked(&crtc->mutex));

@@ -162,6 +220,9 @@ static void tilcdc_crtc_enable(struct drm_crtc *crtc)

reset(crtc);

+ if (priv->rev == 1 && !completion_done(&tilcdc_crtc->palette_loaded))
+ tilcdc_crtc_load_palette(crtc);
+
tilcdc_crtc_enable_irqs(dev);

tilcdc_clear(dev, LCDC_DMA_CTRL_REG, LCDC_DUAL_FRAME_BUFFER_ENABLE);
@@ -200,6 +261,13 @@ void tilcdc_crtc_disable(struct drm_crtc *crtc)
__func__);
}

+ /*
+ * LCDC will not retain the palette when reset. Make sure it gets
+ * reloaded on tilcdc_crtc_enable().
+ */
+ if (priv->rev == 1)
+ reinit_completion(&tilcdc_crtc->palette_loaded);
+
drm_crtc_vblank_off(crtc);

tilcdc_crtc_disable_irqs(dev);
@@ -802,6 +870,14 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
dev_err_ratelimited(dev->dev, "%s(0x%08x): FIFO underfow",
__func__, stat);

+ if (priv->rev == 1) {
+ if (stat & LCDC_PL_LOAD_DONE) {
+ complete(&tilcdc_crtc->palette_loaded);
+ tilcdc_clear(dev,
+ LCDC_RASTER_CTRL_REG, LCDC_V1_PL_INT_ENA);
+ }
+ }
+
/* For revision 2 only */
if (priv->rev == 2) {
if (stat & LCDC_FRAME_DONE) {
@@ -843,6 +919,16 @@ struct drm_crtc *tilcdc_crtc_create(struct drm_device *dev)
return NULL;
}

+ if (priv->rev == 1) {
+ init_completion(&tilcdc_crtc->palette_loaded);
+ tilcdc_crtc->palette_base = dmam_alloc_coherent(dev->dev,
+ TILCDC_REV1_PALETTE_SIZE,
+ &tilcdc_crtc->palette_dma_handle,
+ GFP_KERNEL | __GFP_ZERO);
+ if (!tilcdc_crtc->palette_base)
+ return ERR_PTR(-ENOMEM);
+ }
+
crtc = &tilcdc_crtc->base;

ret = tilcdc_plane_init(dev, &tilcdc_crtc->primary);
--
2.9.3
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