From 6e138f76b676b8c6dfa744db183776b0668ec272 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Thu, 21 Jan 2016 15:20:09 +0000
Subject: [PATCH] drm: etnaviv: extract replacement of WAIT command
Extract out the replacement of the WAIT command with some other command.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
---
drivers/gpu/drm/etnaviv/etnaviv_buffer.c | 32 +++++++++++++++++-------
1 file changed, 23 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
index 7f935e58e4b37..975c11b7fb383 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
@@ -131,6 +131,23 @@ static void etnaviv_buffer_dump(struct etnaviv_gpu *gpu,
ptr, len * 4, 0);
}
+/*
+ * Safely replace the WAIT of a waitlink with a new command and argument.
+ * The GPU may be executing this WAIT while we're modifying it, so we have
+ * to write it in a specific order to avoid the GPU branching to somewhere
+ * else. 'wl_offset' is the offset to the first byte of the WAIT command.
+ */
+static void etnaviv_buffer_replace_wait(struct etnaviv_cmdbuf *buffer,
+ unsigned int wl_offset, u32 cmd, u32 arg)
+{
+ u32 *lw = buffer->vaddr + wl_offset;
+
+ lw[1] = arg;
+ mb();
+ lw[0] = cmd;
+ mb();
+}
+
/*
* Ensure that there is space in the command buffer to contiguously write
* 'cmd_dwords' 64-bit words into the buffer, wrapping if necessary.
@@ -172,7 +189,7 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, unsigned int event,
struct etnaviv_cmdbuf *cmdbuf)
{
struct etnaviv_cmdbuf *buffer = gpu->buffer;
- u32 *lw = buffer->vaddr + buffer->user_size - 16;
+ unsigned int waitlink_offset = buffer->user_size - 16;
u32 back, link_target, link_size, reserve_size, extra_size = 0;
if (drm_debug & DRM_UT_DRIVER)
@@ -219,8 +236,7 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, unsigned int event,
print_hex_dump(KERN_INFO, "cmd ", DUMP_PREFIX_OFFSET, 16, 4,
cmdbuf->vaddr, cmdbuf->size, 0);
- pr_info("link op: %p\n", lw);
- pr_info("link addr: %p\n", lw + 1);
+ pr_info("link op: %p\n", buffer->vaddr + waitlink_offset);
pr_info("addr: 0x%08x\n", link_target);
pr_info("back: 0x%08x\n", gpu_va(gpu, buffer) + back);
pr_info("event: %d\n", event);
@@ -262,12 +278,10 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, unsigned int event,
CMD_WAIT(buffer);
CMD_LINK(buffer, 2, gpu_va(gpu, buffer) + (buffer->user_size - 4));
- /* Change WAIT into a LINK command; write the address first. */
- *(lw + 1) = link_target;
- mb();
- *(lw) = VIV_FE_LINK_HEADER_OP_LINK |
- VIV_FE_LINK_HEADER_PREFETCH(link_size);
- mb();
+ etnaviv_buffer_replace_wait(buffer, waitlink_offset,
+ VIV_FE_LINK_HEADER_OP_LINK |
+ VIV_FE_LINK_HEADER_PREFETCH(link_size),
+ link_target);
if (drm_debug & DRM_UT_DRIVER)
etnaviv_buffer_dump(gpu, buffer, 0, 0x50);
--
2.30.2