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51 lines
1.9 KiB
Diff
51 lines
1.9 KiB
Diff
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From 712bccec241e84e28ccb725fae87d3255d039f42 Mon Sep 17 00:00:00 2001
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From: Dom Cobley <popcornmix@gmail.com>
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Date: Thu, 22 Jun 2023 14:06:40 +0100
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Subject: [PATCH] drm/vc4: hvs: Remove ABORT_ON_EMPTY flag
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ABORT_ON_EMPTY chooses whether the HVS abandons the current frame
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when it experiences an underflow, or attempts to continue.
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In theory the frame should be black from the point of underflow,
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compared to a shift of sebsequent pixels to the left.
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Unfortunately it seems to put the HVS is a bad state where it is not
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possible to recover simply. This typically requires a reboot
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following the 'flip done timed out message'.
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Discussion with Broadcom has suggested we don't use this flag.
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All their testing is done with it disabled.
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Additionally setting BLANK_INSERT_EN causes the HDMI to output
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blank pixels on an underflow which avoids it losing sync.
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After this change a 'flip done timed out' due to sdram bandwidth
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starvation or too low a clock is recoverable once the situation improves.
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Signed-off-by: Dom Cobley <popcornmix@gmail.com>
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---
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drivers/gpu/drm/vc4/vc4_hdmi.c | 1 +
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drivers/gpu/drm/vc4/vc4_regs.h | 1 +
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2 files changed, 2 insertions(+)
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--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
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+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
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@@ -1866,6 +1866,7 @@ static void vc4_hdmi_encoder_post_crtc_e
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VC4_HD_VID_CTL_CLRRGB |
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VC4_HD_VID_CTL_UNDERFLOW_ENABLE |
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VC4_HD_VID_CTL_FRAME_COUNTER_RESET |
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+ VC4_HD_VID_CTL_BLANK_INSERT_EN |
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(vsync_pos ? 0 : VC4_HD_VID_CTL_VSYNC_LOW) |
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(hsync_pos ? 0 : VC4_HD_VID_CTL_HSYNC_LOW));
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--- a/drivers/gpu/drm/vc4/vc4_regs.h
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+++ b/drivers/gpu/drm/vc4/vc4_regs.h
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@@ -799,6 +799,7 @@ enum {
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# define VC4_HD_VID_CTL_CLRSYNC BIT(24)
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# define VC4_HD_VID_CTL_CLRRGB BIT(23)
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# define VC4_HD_VID_CTL_BLANKPIX BIT(18)
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+# define VC4_HD_VID_CTL_BLANK_INSERT_EN BIT(16)
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# define VC4_HD_CSC_CTL_ORDER_MASK VC4_MASK(7, 5)
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# define VC4_HD_CSC_CTL_ORDER_SHIFT 5
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