This is a note to let you know that I've just added the patch titled
drm/vc4: hvs: Configure the HVS COB allocations
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-vc4-hvs-configure-the-hvs-cob-allocations.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 089be1de0444830717ddf52517b078356854f651
Author: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
Date: Wed Dec 7 12:53:12 2022 +0100
drm/vc4: hvs: Configure the HVS COB allocations
[ Upstream commit 1284365e3e8cc33849f90cae20bca36fd7544e24 ]
The HVS Composite Output Buffer (COB) is the memory used to
generate the output pixel data.
Until now the vc4 driver has been relying on the firmware to
have set these to sensible values.
In testing triple screen support it has been noted that only
1 line was being assigned to HVS channel 2. Whilst that is fine
for the transposer (TXP), and indeed needed as only some pixels
have an alpha channel, it is insufficient to run a live display.
Split the COB more evenly between the 3 HVS channels.
Fixes: c54619b0bfb3 ("drm/vc4: Add support for the BCM2711 HVS5")
Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221207-rpi-hvs-crtc-misc-v1-1-1f8e0770798b@xxxxxxxxxx
Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
index c4453a5ae163a..d615ba7db9209 100644
--- a/drivers/gpu/drm/vc4/vc4_hvs.c
+++ b/drivers/gpu/drm/vc4/vc4_hvs.c
@@ -776,7 +776,7 @@ static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
struct vc4_hvs *hvs = NULL;
int ret;
u32 dispctrl;
- u32 reg;
+ u32 reg, top;
hvs = drmm_kzalloc(drm, sizeof(*hvs), GFP_KERNEL);
if (!hvs)
@@ -912,6 +912,60 @@ static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
HVS_WRITE(SCALER_DISPCTRL, dispctrl);
+ /* Recompute Composite Output Buffer (COB) allocations for the displays
+ */
+ if (!vc4->is_vc5) {
+ /* The COB is 20736 pixels, or just over 10 lines at 2048 wide.
+ * The bottom 2048 pixels are full 32bpp RGBA (intended for the
+ * TXP composing RGBA to memory), whilst the remainder are only
+ * 24bpp RGB.
+ *
+ * Assign 3 lines to channels 1 & 2, and just over 4 lines to
+ * channel 0.
+ */
+ #define VC4_COB_SIZE 20736
+ #define VC4_COB_LINE_WIDTH 2048
+ #define VC4_COB_NUM_LINES 3
+ reg = 0;
+ top = VC4_COB_LINE_WIDTH * VC4_COB_NUM_LINES;
+ reg |= (top - 1) << 16;
+ HVS_WRITE(SCALER_DISPBASE2, reg);
+ reg = top;
+ top += VC4_COB_LINE_WIDTH * VC4_COB_NUM_LINES;
+ reg |= (top - 1) << 16;
+ HVS_WRITE(SCALER_DISPBASE1, reg);
+ reg = top;
+ top = VC4_COB_SIZE;
+ reg |= (top - 1) << 16;
+ HVS_WRITE(SCALER_DISPBASE0, reg);
+ } else {
+ /* The COB is 44416 pixels, or 10.8 lines at 4096 wide.
+ * The bottom 4096 pixels are full RGBA (intended for the TXP
+ * composing RGBA to memory), whilst the remainder are only
+ * RGB. Addressing is always pixel wide.
+ *
+ * Assign 3 lines of 4096 to channels 1 & 2, and just over 4
+ * lines. to channel 0.
+ */
+ #define VC5_COB_SIZE 44416
+ #define VC5_COB_LINE_WIDTH 4096
+ #define VC5_COB_NUM_LINES 3
+ reg = 0;
+ top = VC5_COB_LINE_WIDTH * VC5_COB_NUM_LINES;
+ reg |= top << 16;
+ HVS_WRITE(SCALER_DISPBASE2, reg);
+ top += 16;
+ reg = top;
+ top += VC5_COB_LINE_WIDTH * VC5_COB_NUM_LINES;
+ reg |= top << 16;
+ HVS_WRITE(SCALER_DISPBASE1, reg);
+ top += 16;
+ reg = top;
+ top = VC5_COB_SIZE;
+ reg |= top << 16;
+ HVS_WRITE(SCALER_DISPBASE0, reg);
+ }
+
ret = devm_request_irq(dev, platform_get_irq(pdev, 0),
vc4_hvs_irq_handler, 0, "vc4 hvs", drm);
if (ret)
